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The urgent requirement of carbon reduction in the world provides wood products a historical opportunity to play a crucial role to fix carbon dioxide and reduce carbon emission. It is essential to reveal the in situ growth mechanism of copper nanoparticles on eucalyptus scrimber surface. Cu4(SO4)(OH)6 nanoflowers are in situ synthesized successfully on the surface of eucalyptus scrimber via a simple hydrothermal process in this work. The detailed nucleation and in situ growth process of Cu4(OH)6SO4 nanoparticles on the surface of eucalyptus scrimber, characterized by the trajectory of size evolution, are revealed first in this work. According to the classical nucleation theory, the nucleation stage of as prepared Cu4(SO4)(OH)6 nanoflowers includes nucleus formation and nucleus growth. Although the same initial precursor reactant is obtained at the nucleation stage, there are two types of early nanoparticles, with morphology of fusiform and strip shape being self assembled to nanoflower structure during the growth stage. Further, the modified eucalyptus scrimber exhibits excellent superhydrophobicity, UV durability, mold and moisture resistance, as well as reversible property. Therefore, the proposed in situ growth kinetics related to Cu4(OH)6SO4 nanoparticles on wood surface have potential to be a reference to develop multifunctional superhydrophobic wood‐based material for variable applications. [ABSTRACT FROM AUTHOR]

Wellbore integrity is significant to maintain and improve the production performances of shale wells. In Duvernay Canada, casing deformation near the top of Ireton with a few natural faults and cracks is severe during multi-fracturing. It is urgent to reveal the mechanism to reduce the risk of wellbore failure. In this paper, casing deformation and micro-seismic signal at casing shoe is analysed. The maximum deformation of the casing can reach to be 44.4mm. Based on the focal mechanism, it is easy to get the formation slip displacement. Under the condition of geology and wellbore geometry, a three-dimensional stage finite element method considering the whole drilling process is established to simulate the influence of fault on casing deformation. The results indicate that cement sheath at casing shoes intend to be failure during fracturing, where the fracturing fluid will immerse into the formation of Ireton thorough the micro-annulus of cement sheath. When the pore pressure is large enough to activate the natural fault, the micro-seismic signal at the casing shoe is frequent with the magnitude up to 3. Under this condition, the faults slippage can be 55 mm, and the casing deformation will be 34.9 mm. This is consistent with the actual deformation of casing. Along easy-slip formation position, cement property and wellbore structure should be optimized to prevent fracturing fluid entering the formation. Fracturing operation should be optimized to avoid generating high-magnitude seismic signals during the fracturing process, thereby reducing the possibility of casing shear deformation.

Since the stability of engineering rock masses has important practical significance to projects like mining, tunneling, and petroleum engineering, it is necessary to study mechanical properties and stability prediction methods for rocks, cementing materials that are composed of minerals in all shapes and sizes. Rocks will generate acoustic emission during damage failure processes, which is deemed as an effective means of monitoring the stability of coal rocks. In the meantime, actual mining and roadway surrounding rocks tend to have transverse effects; namely, the transverse scale is larger than the length scale. Therefore, it is important to explore mechanical properties and acoustic emission properties of rocks under transverse size effects. Considering the transverse scale effects of rocks, this paper employs the microparticle flow software PFC2D to explore the influence of different aspect ratios on damage mechanics and acoustic emission properties of rocks. The results show that (1) the transverse scale affects uniaxial compression strength of rocks. As the aspect ratio increases, uniaxial compression strength of rocks decreases initially and later increases, showing a V-shape structure and (2) although it affects the maximum hit rate and the strain range of acoustic emission, it has little influence on the period of occurrence. As the transverse scale increases, both damage degree and damage rate of rocks decrease initially and later increase.