Wear and thermal behavior of basalt fiber reinforced rice husk/polyvinyl chloride composites

Plant fiber reinforced polymer composites (PFRPs) in practical application are often subjected to both complex friction and variable temperature environments. The present work explores the possibility of reinforcing rice husk/polyvinyl chloride (RH/PVC) composites with basalt fibers (BF) for developing a new wear resistant material with improved thermal stability. The results showed that the structural strength and wear resistance of the composites increased at first and then decreased with an increasing ratio of BF/RH, the highest value occurred at a BF/RH ratio of 8/42. The thermal stability of composites had a positive relationship with BF/RH ratio. The composites added with BF all possessed improved performance in comparison with unadded composites. Hence, the findings of this article proposed some new perspectives on improving the wear resistance and thermal stability of PFRPs that would broaden their practical application.     

Hydrogeochemical Processes and Inverse Modeling for a Multilayer Aquifer System in the Yuaner Coal Mine,Huaibei Coalfield,China

Coal mining can dramatically change hydrogeological conditions and induce serious environmental problems. Fifty groundwater samples were collected from the main aquifers in the Yuaner coal mine (Anhui Province, China). The results show that the main hydrogeochemical processes in the mine include dissolution, precipitation, pyrite oxidation, desulfurization, and cation exchange. The Neogene porous aquifer is affected by groundwater flow conditions; its main hydrogeochemical processes are dissolution of carbonate minerals and gypsum, and cation exchange. The Permian coal measure’s fractured sandstone aquifer was confirmed to be controlled by the region’s geological structure; its main hydrogeochemical processes are desulfurization and cation exchange. The Carboniferous Taiyuan limestone aquifer was determined by both groundwater flow conditions and regional geological structure; its main hydrogeochemical processes are dissolution of carbonate minerals and gypsum, pyrite oxidation, and cation exchange. Additionally, hydrogeochemical inverse modeling of the groundwater flow path confirm the hydrochemistry results and principal component analysis.

     

Synthesis of bristlegrass-like Co-doped Ni2P composites on Ni foam for overall seawater splitting

Seawater is the most abundant resource on earth, so developing cost-effective, highly durable corrosion resistance and efficient electrocatalysts are crucial to enhance seawater splitting. Herein, we prepared 3D bristlegrass-like Co-doped Ni₂P (Co-Ni₂P) composites supported on Ni foam (NF) through a facile solvothermal method combined and a subsequent phosphatization treatment. Benefiting from the unique structure, Co-Ni₂P shows excellent electrocatalytic activity as an electrode material for both the hydrogen evolution reaction (HER, low overpotential of 116 mV at 50 mA cm^?2) and oxygen evolution reaction (OER, low overpotential of 266 mV at 50 mA cm^?2). Moreover, the as-prepared Co-Ni₂P composites exhibit excellent stability and corrosion resistance in an alkaline medium. Density functional theory (DFT) calculations were employed to evaluate the H1 adsorption of Co-Ni₂P, and the results proved the high catalytic activity for the HER. This study provides new materials with a unique morphology for overall water splitting.     

Experimental study on the deformation and failure mechanism of overburden rock during coal mining using a comprehensive intelligent sensing method

Understanding the spatiotemporal evolution of overburden deformation during coal mining is still a challenge in engineering practice due to the limitation of monitoring techniques. Taking the Yangliu Coal Mine as an example, a similarity model test was designed and conducted to investigate the deformation and failure mechanism of overlying rocks in this study. Distributed fiber optic sensing (DFOS), high-density electrical resistivity tomography (HD-ERT) and close-range photogrammetry (CRP) technologies were used in the test for comprehensive analyses. The combined use of the three methods facilitates the investigation of the spatiotemporal evolution characteristics of overburden deformation, showing that the mining-induced deformation of overburden strata was a dynamic evolution process. This process was accompanied by the formation, propagation, closure and redevelopment of separation cracks. Moreover, the key rock stratum with high strength and high-quality lithology played a crucial role in the whole process of overburden deformation. There were generally three failure modes of overburden rock layers, including bending and tension, overall shearing, and shearing and sliding. Shear failure often leads to overburden falling off in blocks, which poses a serious threat to mining safety. Therefore, real-time and accurate monitoring of overburden deformation is of great significance for the safe mining of underground coal seams.     

Recent advances during CH4 dry reforming for syngas production: A mini review

Given the continuing issues of environment and energy, methane dry reforming for syngas production have sparked interest among researchers, but struggled with the process immaturity owing to catalyst deactivation. This review summarizes the recent advances in the development of efficient and stable catalysts with strong resistance to coking and metal sintering, including the application of novel materials, the assessment of advanced characterizations and the compatibility to improved reaction system. One feasible option is the crystalline oxide catalysts (perovskite, pyrochlore, spinel and LDHs), which feature a fine metal dispersion and surface confinement effect via a metal exsolution strategy and exhibit superior reactivity and stability. Some new materials (h-BN, clays and MOFs) also extend the option because of their unique morphology and microstructure. It also is elaborated that progresses were achieved in advanced characterizations application, leading to success in the establishment of reaction mechanisms and attributions to the formed robust catalysts. In addition, the perspective described the upgrade of reaction system to a higher reaction efficiency and milder reaction conditions. The combination of efficient reaction systems and robust catalysts paves a way for a scaling-up application of the process.     

Polyaniline-based networks combined with Fe3O4 hollow spheres and carbon balls for excellent electromagnetic wave absorption

Polyaniline (PANI)-based networks combined with Fe₃O₄ hollow spheres and carbon balls (FCP) for improved electromagnetic wave (EMW) absorption were investigated using an easy-to-industrialize solvothermal and physical method. Hollow structure Fe₃O₄ spheres with a lower density than that of the common solid sphere were prepared. As a thin and light magnetic material, Fe₃O₄ hollow spheres generate magnetic loss, carbon balls and PANI networks generate dielectric loss. The magnetic and conductive parts play appropriate roles in achieving complementarity in the EMW absorption. The relatively high specific surface area introduced by PANI networks promotes interfacial polarization and further supports dielectric loss. In conclusion, the above reasons provide multiple attenuation mechanisms. Samples FCP1 (?65.109 dB, at 12.800 GHz, 1.966 mm, from 5.6 to 18.0 GHz) and FCP2 (?61.033 dB, at 8.480 GHz, 3.328 mm, from 4.3 to 18.0 GHz) demonstrated a wide bandwidth, a small thickness, a minimum reflection loss (R_L), and a low loading ratio (25%) in paraffin-based composites. Specifically, their loading ration of 25% is much lower than the loading ratio of conventional materials (usually 50% and above). In addition, the bandwidth is excessively wide, above 12 GHz, possessing good absorption performance in continuous intervals with different thicknesses. Such excellent characteristics have rarely been reported in literature.     

高地压严重突出区域下向穿层钻孔预抽消突技术

利用工作面高抽巷施工掩护顺槽掘进工作面下向穿层条带预抽钻孔,通过对钻场底板深、浅孔注浆封堵围岩裂隙解决了孔内返水不畅难题;采取了"两堵一注"封孔方式确保封孔严密不漏气;孔内全程下吹水管,实现了单孔、分组、定时吹水工作目标,提高了下向消突钻孔抽采效果,形成了一套高效、快速的下向穿层钻孔消突管理模式,实现了高地压严重突出区域煤层高效消突以及技术经济一体化目标,安全经济效益显著。     

Photoluminescence and temperature sensing of lanthanide Eu3+ and transition metal Mn4+ dual-doped antimoniate phosphor through site-beneficial occupation

For a long time, rare-earth ion-doped phosphors have been widely used in temperature sensing because of their excellent light-emitting properties. However, most of the rare earth elements are relatively rare and expensive, so the transition group elements that are economical and easy to obtain have been favored by researchers. This paper presents a new type of phosphor doped with rare earth ion and transition metal for optical temperature measurement. In recent years, Mn⁴⁺-doped phosphors have attracted wide attention because of their strong deep red light-emitting properties. La₂LiSbO₆ provides a good host environment for Mn⁴⁺ and Eu³⁺ due to its unique crystal structure. In this paper, a series of La₂LiSbO₆ phosphors singly doped with Mn⁴⁺ and Eu³⁺, and co-doped with Eu³⁺/Mn⁴⁺ were synthesized. The crystal phases and optical properties of these materials were characterized and analyzed in detail. We specifically studied the temperature dependence of the fluorescence intensity of the optimized La₂LiSbO₆: Eu³⁺, Mn⁴⁺ phosphors at 303K–523K. The experimental results prove that the thermal responses of Mn⁴⁺ and Eu³⁺ are different. With increasing temperature, the thermal quenching of the Mn⁴⁺ fluorescence intensity is much faster than that of Eu³⁺, so the temperature characteristics can be explored by the fluorescence intensity ratio (FIR) of Eu³⁺ to Mn⁴⁺. At 523 K, its maximum relative sensitivity and maximum absolute sensitivity can reach 0.891% K⁻¹ and 0.000264 K^-1, respectively. Our experimental analysis shows that La₂LiSbO₆:Eu³⁺/Mn⁴⁺ phosphors have relatively high temperature sensitivity and have potential application prospects in the field of high temperature sensing.     

地沟油水解法基于浮选的再生技术研究*

本文选择食堂废弃的地沟油为研究对象,通过控制水解条件,获得不同性质的地沟油改性捕收剂。分别探究温度、催化剂、乳化剂用量等因素对地沟油水解的影响规律,确定其最佳的改性条件。采用接触角测定表征地沟油的改性效果,通过比较地沟油改性捕收剂在固废浮选方面的应用效果。结果表明地沟油改性剂具有一定的捕收作用,在浮选分离领域,可替代传统脂肪酸类捕收剂及非极性烃类捕收剂的使用。