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Obtaining the position of underground trapped personnel quickly and precisely is a key issue for life information detection in the early stage of borehole rescue. In the process of vertical drilling and rescue, due to the collapse of the roadway in the detection area or the displacement of the final hole position, it is impossible to obtain the position of the trapped personnel quickly and accurately. It delays the golden time of rescue and affects the safety of personnel. Through conducting a UWB radar wave transmission attenuation study, a rescue plan can be quickly formulated for on-site rescue commanders. This paper analyzes the current situation and demand of UWB radar wave application in mine borehold rescue. Combined with the background of mine borehold rescue, it is pointed out the attenuation law of UWB radar wave transmission. The study analyzes the influence of the characteristic parameters of the medium on the attenuation of radar wave transmission from the perspective of anisotropy of the medium. The influence of dielectric parameters on radar wave transmission attenuation is analyzed from four aspects: dielectric constant, conductivity, magnetic permeability and spatiotemporal variation. The influence of radar characteristic parameters on radar wave transmission attenuation is analyzed from two aspects: radar frequency and polarization. Based on the above analysis, it is pointed out that there are few studies on the simultaneous penetration of UWB radar waves through anisotropic media such as coal and rock masses and the mechanism of media propagation and attenuation. There are few theories and experiments on UWB radar wave transmission attenuation in complex and changeable underground or simulating disaster environments. And there are few summaries of relevant laws. The mapping relationship database between key parameters and influencing factors of UWB radar waves is not yet complete. The key technologies to be studied in the future are given as follows. It is suggested to conduct research on anisotropic media such as coal and rock masses at both macro and micro levels. It is suggested to establish an experimental simulation system for radar wave transmission attenuation under catastrophic environmental conditions. It is suggested to add research on UWB radar signal propagation characteristics and channel modeling numerical simulation in unstructured environments after disasters.

Ta-doped lithium-lanthanum-zirconium-oxygen (Li6.5La3Zr1.5Ta0.5O12, LLZTO) solid electrolytes with a high ionic conductivity at room temperature were prepared by the solid-phase reaction method, and the effects of irradiated electron beams on their structure and properties were investigated in detail. The results showed that no other heterogeneous phases were produced after irradiation with different doses (250 kGy and 500 kGy) of electron beams, and the lattice spacing became larger with an increase in the dose, which is conducive to the reduction of the diffusion energy barrier of ions in the lattice. First-principles calculations revealed that the Li+ diffusion energy barrier of the low-dose electron-beam irradiated sample was reduced by 0.07 eV compared with that of the unirradiated sample, suggesting that the defects created by irradiation can promote Li+ diffusion. An AC impedance test of the electrolytes before and after irradiation further confirmed that low-dose electron beam irradiation is beneficial for enhancing their ionic conductivity. Exploring the effect of electron beam irradiation on the structure and conductivity of LLZTO oxide solid state electrolytes holds significance in the study of solid state electrolytes.

Investigations on the damage and degradation mechanisms of epoxy resin under a high-energy irradiation and improvement in its stability in irradiation environments are crucial to expand the application of epoxy resin in numerous fields including the aerospace and nuclear industries. In this study, graphene quantum dots (GQDs) were used as free radical scavengers to slow down the degradation of epoxy resin under a γ-irradiation environment, and the anti-irradiation mechanism of the GQDs on epoxy resin was investigated. The results demonstrated that following irradiation, the mechanical properties of epoxy resin exhibited a reduction of 49%, accompanied by a decrease in glass transition temperature by 4.4 ℃. Similarly, the mechanical properties of graphene quantum dots/epoxy resin (GQDs/EP) composites experienced a decline of 35%, along with a decrease in glass transition temperature by 2.2 ℃. Notably, upon the incorporation of GQDs, the generation of free radicals within irradiated GQDs/EP composites was significantly suppressed compared to pure resin. Furthermore, GQDs nanoparticles enhanced both the mechanical properties and thermal stability of epoxy resin prior to and after irradiation. Therefore, GQDs nanoparticles can be used as free radical scavenger to effectively improve the irradiation stability of epoxy resin. The scavenging mechanisms for free radicals mediated by GQDs is closely associated with sp2 carbon domains and surface functional groups. This study provides a novel concept and method to improve the stability of epoxy resin under γ-ray radiation.

Green extraction of the active lignans from Schisandra chinensis has received considerable attention due to their promising applications in the biomedical field. In this study, microwave‐assisted deep eutectic solvent method was used to simultaneously extract five lignans: Schizandrol A, Schizandrol B, Schisantherin A, Schisandrin A and Schizandrin B. The extraction parameters were optimized according to the calculated comprehensive score obtained from the analytic hierarchy process combined with the entropy weight method. The optimal extraction conditions were that the molar ratio of choline chloride and glycolic acid is 4:1, water content is 30% (V/V), solid–liquid ratio is 1:20 (Wg:VmL), extraction time is 20 min, and extraction temperature is 70°C, under which the extraction rate of the five lignans were 10.89, 8.616, 4.019, 4.893, and 5.318 mg/g. These results confirmed that our extraction method is efficient and feasible for green extraction of lignans from S. chinensis. [ABSTRACT FROM AUTHOR]

We successfully synthesized a series of O3‐type NaNi1/3Fe1/3Mn1/3−xZrxO2 (x = 0, 0.01, 0.02, 0.04) cathode materials by the solid‐state reaction method. Energy dispersion spectroscopy, X‐ray diffraction (XRD), and X‐ray photoelectron spectroscopy results confirmed the successful incorporation of Zr elements into the lattice to substitute Mn. Due to the introduction of Zr4+, the crystal structure modulation of O3‐NaNi1/3Fe1/3Mn1/3O2 has been realized. By increasing the Zr4+ content, the width of the sodium diffusion layer expands, thereby facilitating the diffusion of sodium ions. Consequently, the material exhibits a remarkable enhancement in high‐rate capability. At the same time, increasing the Zr4+ content results in a notable decrease in both the average bond length of TM−O and the thickness of the TMO6 octahedron in the transition metal layer, resulting in a significant improvement in the cycling performance and structural stability of the cathode material. Additionally, the in‐situ XRD results demonstrate that the optimized cathode composition of O3‐NaNi1/3Fe1/3Mn1/3–0.02Zr0.02O2 (NFMZ2) undergoes a reversible phase transition of O3 → O3 + P3 → P3 → O3 + P3 → O3 during the charge–discharge process. [ABSTRACT FROM AUTHOR]

Magnetic anisotropy is an important character for magnetic materials. In this work, magnetic anisotropy of (110)-oriented ferrimagnetic NiCo2O4 (NCO) thin films deposited epitaxially on MgAl2O4 substrates by pulsed laser deposition is studied and compared with (001)-oriented NCO films. While the (001)-oriented films show a perpendicular magnetic anisotropy with the out-of-plane [001] direction as the magnetic easy axis, a jump in magnetic hysteresis loop is observed for the (110)-oriented films with a field applied vertically along the out-of-plane [110] direction. This jump in hysteresis loop is associated with a spin reorientation transition, depending on the applied field and temperature. Magnetic force microscopy reveals that this spin reorientation develops as domains nucleate, grow, and coalesce. This spin reorientation transition is discussed in terms of the competition between different magnetic anisotropy in an external field. [ABSTRACT FROM AUTHOR]

Ramie composites have been widely used in automobiles, daily necessities, aerospace, ships, cruise lines, etc., but their flame retardant properties are relatively poor, which is difficult to meet the flame retardant performance requirements of composites for rail transit. In order to improve the properties of ramie reinforced composites, flame retardant treatment is necessary. In this paper, phosphorus flame retardant phytic acid (PA) was used to modify ramie fabric, and then the composites were prepared. The flame retardancy and mechanical properties of ramie reinforced composites were investigated. It was found that the flame retardancy of ramie composites was improved after flame retardant modification with phytic acid, but the mechanical properties were decreased. In order to improve the mechanical properties of PA ramie composites, two kinds of layered PA ramie/glass fiber hybrid composites were prepared by replacing part of ramie with glass fiber. The results show that the addition of glass fiber can improve the mechanical properties and flame retardancy of composites. [ABSTRACT FROM AUTHOR]