A novel approach to enhance wellbore stability was put forth, based on the wellbore rock properties and instability mechanism of the hydrate reservoir, given the issue of wellbore instability when using water-based drilling fluids (WBDFs) in drilling operations, in weakly cemented muddy fine silt reservoirs of natural gas hydrates in the South China Sea. Three main strategies were used to increase the stability of reservoirs: enhancing the underwater connection between sandstone particles and clay minerals, preventing clay hydration from spreading and expanding, and strengthening the stability of hydration skeleton structure. An appropriate drilling fluid system was built with soil phase containing wellbore stabilizer. Sulfonic acid groups and electrostatic interaction were introduced based on the characteristics of underwater adhesion of mussels. Through the process of free radical polymerization, a zwitterionic polymer containing catechol groups named DAAT was prepared for application in natural gas hydrate reservoir drilling. DAAT is composed of tannic acid (TA), dimethyl diallyl chloride ammonium chloride (DMDAAC), 2-acrylamide-2-methylpropanesulfonic acid (AMPS) and acrylamide (AM). Experimental results from mechanical property testing reveal an adhesion force of up to 4206 nN between SiO2 and 5 wt % DAAT, demonstrating its ability to bind quartz sand particles effectively. The compressive strength and cohesion of the cores treated with DAAT increased by 58.33 wt % and 53.26 wt %, respectively, at -10 degrees C, compared with pure ice particle cores. This demonstrates DAAT can significantly enhance the compressive strength and cohesion of the core. Furthermore, the adhesion force between DAAT and hydrate particles reaches up to 344.4 mN/m, significantly improving the structural stability between hydrate particles. It demonstrates excellent adhesive properties to hydrate particles. In addition to adsorbing clay minerals, rocks, and hydrate particles, DAAT also forms hydrogen bonds with argillaceous fine silt particles with its low temperature cohesiveness characteristic. As a result, it improves the cohesion between core particles, and enhances the adhesion between hydrates and rocks, thereby enhancing the stability of hydrate reservoirs. In summary, DAAT is characterized by a simple preparation process, cost-effectiveness, and environmental friendliness. It is an innovative and practical material for enhancing wellbore stability in WBDFs for natural gas hydrate exploration in the South China Sea.

Underground structures are subject to deterioration conditions in which water leakage occurs through cracks due to the long-term influence of soil and groundwater. Therefore, composite waterproofing sheets can play an important role in securing the leakage stability of structures by combining them with concrete structures. In this study, a total of eight composite waterproofing sheets were used according to the thickness of the compound and the properties of the material attached to the concrete, and the deformation characteristics at the bonding surface were identified through repeated tensile tests. Types A, B, and C, with a compound thickness of 1.35 to 1.85 mm and a single layer, had strong bonding performance, with a deformation rate of 0.5 to 2 x 10-4 and a DE/RE ratio of 0.3 to 1.3; tensile deformation progressed while maintaining integrity with the concrete at the bonding surface. Types D and E were viscoelastic and non-hardening compounds with a compound thickness of 1.35 to 3.5 mm, where the strain rate due to tensile deformation was the lowest, at 0.1 x 10-4 or less, and the DE/RE ratio was -5 to 3; therefore, when internal stress occurs, the high-viscosity compound absorbs it, and the material is judged to have low deformation characteristics. Types F, G, and H, which were 2 to 2.9 mm thick and had two layers using a core material, were found to have characteristics corresponding to tensile deformation, as the strain rate increased continuously from 0.2 to 0.5 x 10-4, and the DE/RE ratio increased up to 8 mm of tensile deformation.

The adhesion property of soil on the metal surface was tested by the orthogonal experiment with 4 factors and 3 levels based on piston pull out method. A regression model of adhesion stress and the factors including moisture content(X-1), pressing time(X-2), settling time(X-3) and separation velocity (X-4) was established. The experiment results show that the influence of each factor on adhesion stress is ranked as X- 1 approximate to X (2) approximate to X (3) > X (4) > X- 3 X- 4 , and the adhesion stress shows an 'S' curve with the increase of separation velocity. The DEM parameters of the soil were calibrated based on the test results, and the contact and disturbance state of soil particles during the test were studied by discrete element method (DEM) using JKR model. The simulation tests show that the maximum adhesion stress occurs when the particles are about to separate from the probe surface, and the soil disturbance state is hierarchical.

Strong soil-tool adhesion on soil-engaging components is a key factor leading to the energy consumption and agricultural tool damage in agriculture tillage. A number of chemical and physical strategies have been widely proposed to eliminate soil-tool adhesion, but subjecting to limited anti-soil capabilities. In this work, we present an earthworm-inspired matter-repellent surface by stably grafting dimethyl dimethoxy silicane and infusing silicone oil, allowing for a superior resistance to soil-steel adhesion in an eco-friendly mode. The presence of such coating enables a theoretical adhesion work reduction by 10 times, thereby resulting in robust repellency to stick soil. Furthermore, the influence of water fraction in soil, adhesion velocity, and adhesion angle on the anti-soil performance of matter-repellent surfaces are fully revealed to guide its potential application in agricultural tools. It is anticipated that incorporating our matter-repellent coating into soil-engaging components is beneficial to the development of agricultural machinery.

Historically, cow dung has been widely used as a biostabilizer in earth building, although the scientific research on this subject is still limited. The available research provides evidence of the positive effects of this bioaddition on earthen blocks and plasters, as it improves their physical and mechanical properties and durability in water contact. The present research does not aim to characterize biostabilized earthen mortars or to explain the interaction mechanisms between the earth and cow dung components, because this topic has already been investigated. Instead, it aims to investigate strategies to optimize the collection and processing of cow dung so as to optimize their effects when used in earth-plastering mortars, as well as considering the effects of using them fresh whole, dry whole, and dry ground (as a powder); the effects of two different volumetric proportions of cow dung addition, 20% and 40% (of the earth + added sand); the effects of 72 h (fermentation-humid curing) before molding the biostabilized mortar; the influence of the cow diet; and the potential of reusing cow dung stabilized mortars. The results show that as the freshness of the cow dung increases, the mortar's durability increases under water immersion, as well as the mechanical and adhesive strength. Collecting cow dung fresh and drying (composting) it in a plastic container is more efficient than collecting cow dung that is already dry on the pasture. The cow diet and the use of dry (composted) cow dung, whole or ground into a powder, does not result in a significant difference. A 72 h period of humid curing fermentation increases the adhesive strength and durability under water. The proportion of 40% promotes better durability under water, but 20% offers greater mechanical and adhesive strength. Finally, cow dung addition does not reduce the reusability of the earth mortar. The new mortar obtained by remixing the mortar with water presents increased properties in comparison to the original reference mortar with no cow dung addition. Therefore, the contributions of this research are innovative and important, offering technical support in the area of biostabilized earth-plastering mortars. Furthermore, it is emphasized that cow dung addition can be optimized as an efficient traditional solution to increase the mechanical resistance, but especially to increase the durability of earth mortars when in contact with water. This effect is particularly important for communities lacking financial resources, but also reveals the possibility of using eco-efficient waste instead of binders obtained at high firing temperatures.

Mechanical adhesion among lunar regolith particles significantly influences the shear characteristics of lunar regolith. However, experimental limitations on Earth and challenges in capturing particle-scale information obscure the microscopic mechanisms of adhesion and its interaction with other particle properties, such as shape. This study employs the Discrete Element Method to bridge this gap by incorporating mechanical adhesion and simplifying the particle shape effect. Numerical triaxial shear tests were performed on representative volume elements under densities representative of lunar surface. The study introduced a simplified shape parameter, the rolling friction coefficient mu r, r , representing particle 3D sphericity, which ranged from 0.025 to 1.6. Additionally, the particle surface energy density gamma was adjusted from 0 to 1.28 x 10-- 2 J/m2 2 to model the effects of mechanical adhesion. Stress-strain relationships, friction angles, and microscale mechanics parameters were thoroughly analyzed. Simulation results reveal that under low stress, the e c-ln p relationship remains linear, consistent with critical state sand theory. Significant variability in macro properties is influenced by micro-Newton adhesive forces and rolling friction coefficients (0.1-0.8), particularly in particles with notable irregularities, where adhesion profoundly affects mechanical properties, requiring precise calibration. This research advances the understanding of the shear behavior of lunar regolith, providing critical insights for future simulations and experimental designs.

This article presents the development of laminate biocomposite via film stacking technique (FST) represents a method for processing fiber-reinforced thermoplastic laminate composites. The primary difficulty is the compatibility between the hydrophilic natural fibers and the hydrophobic PLA. With these limitations, the utilization of fiber content exceeding 50 wt% remains unfeasible. The PVA-based adhesives spraying technique is used to improve compatibility. Additionally, the effect of four different compatibilizer adhesives applied between the layers was examined: polyvinyl alcohol (PVA), PVA modified with 3-(trimethoxysilyl) propyl methacrylate (modified PVA), PVA-microfibrillated cellulose (PVA-MFC), and PVA-MFC modified with 3-(trimethoxysilyl) propyl methacrylate (modified PVA-MFC). The findings of the study demonstrate that the natural fibers/PLA laminate biocomposite comprises 65 wt% fiber and 35 wt% PLA, thus achieving successful preparation of laminate biocomposites containing over 50 wt% fibers using the FST technique. In comparison to PVA, modified PVA elevated the flexural strength of the laminate biocomposite by up to 122 %. The modified PVA-MFC compatibilizer, when compared with modified PVA, enhanced impact strength by up to 148 %, reduced surface polarity by 31 %, and notably improved thermal stability. In a QUV accelerated weathering test, all the laminates exhibited reduced flexural modulus and flexural strength, but the flexural strength of all the tested materials remained above 50 MPa. In soil burial tests, the PVA laminate exhibited the most rapid decomposition, whereas the modified PVA-MFC laminate demonstrated a notably slower degradation rate. Accelerated weathering notably increased the decomposition of the materials in soil. The modified PVA-MFC laminate emerged as the optimal material for producing a high-strength biodegradable laminate biocomposite, due to its superior mechanical and thermal properties, rendering them suitable for applications requiring structural support, such as interior construction, stage floors, furniture, and building interior decoration materials.

Plant seeds and fruits, like those of Ocimum basilicum, , develop a mucilaginous envelope rich in pectins and cellulosic fibers upon hydration. This envelope promotes adhesion for attachment to soils and other substrates for dispersal and protection of the seed for a safe germination. Initially at hydration, the mucilage envelope demonstrates low adhesion and friction, but shows increasing adhesive and frictional properties during dehydration. However, the mechanisms underlying the cellulose fiber arrangement and the mechanical properties, especially the elasticity modulus of the mucilage envelope at different hydration conditions are not fully known. In this study, which is based on scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM) and light microscopy, the structure of the seed coat and arrangement of the cellulose fibers of basil seeds were characterized. Moreover, we performed pull-off force measurements to estimate adhesive properties and JKR-tests to estimate E-modulus of the mucilage at different hydration levels. Microscopy results demonstrate that cellulose fibers are split at their free ends into smaller fibrils, which might enhance the adhesive properties of the mucilage. Adhesive forces in contact increased during dehydration and reached maximum of 33 mN shortly before complete dehydration. The E-modulus of the mucilage changed from 1.4 KPa in water to up to 2.1 MPa in the mucilage at the maximum of its adhesion performance. Obtained results showed hydrogel-like mechanical properties during dehydration and cellulose fiber structures similar to the nanofibrous systems in other organisms with strong adhesive properties. Statement of significance This paper reveals the hierarchical cellulose fiber structure in Ocimum basilicum's mucilaginous seed coat, suggesting increased fiber splitting towards the end, potentially enhancing adhesion contact areas. Mechanical tests explore elasticity modulus and adhesion force during various hydration stages, crucial as these properties evolve with mucilage desiccation. A rare focus on mucilaginous seed coat mechanical properties, particularly cellulose-reinforced fibers, provides insight into the hydrogel-like mucilage of plant seeds. Adhesion forces peak just before complete desiccation and then decline rapidly. As mucilage water content decreases, the E-modulus rises, displaying hydrogel-like properties during early dehydration stages with higher water content. This study might bring the focus to plant seeds as inspiration for biodegradable glues and applications for hydrogel research. (c) 2024 The Author(s). Published by Elsevier Ltd on behalf of Acta Materialia Inc. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ )

In this work, a tribological approach was used to distinguish the synergistic effects of mechanical removal and chemical removal (i.e. dissolution) of a layer of representative food soil from a solid surface, using a tribometer, Mini Traction Machine (MTM). Gravimetric and wear measurements of the soil were used to calculate the cleaning rates of burnt tomato puree on a stainless-steel disc, and the corresponding frictional characteristics offers insight of the mechanical removal. The cleaning due to soil dissolution (chemical removal) was quantified by UV-Vis measurements. The overall cleaning rates of food soil featured a linear reduction in mass over time, with a scaled removal rate k = 0.0046 s-1 (5 N applied force and 100 mm s-1 relative velocity), for most cases studied. It was observed that the cleaning rate can be improved with an increasing mechanical load or speed (50% from 1 to 2.5 N and 13% from 50 to 100 mm s-1), but is independent of the initial mass. UV-Vis measurements show that by increasing the load or speed the removal of chunks of burnt tomato puree was enhanced more than removal attributed to dissolution. Similar values of cleaning rates for most experimental parameters were extracted from both the gravimetric and wear measurements. Adhesion and cohesion measurements of the burnt tomato puree were conducted with a micromanipulator. It was found that adhesion forces are higher than cohesion for short soaking times, but for longer times the adhesion forces became weaker and with the additional shear rate in the MTM cleaning experiment, adhesion failure was observed in many cases by the end of the experiment. Indentation measurements showed the change in mechanical properties of the food foulant with a few minutes of soaking in water.

The process of filling self-compacting cement grout (SCCG) into granular packing without disturbing the granular skeleton culminates in the formation of a well-defined cemented granular materials (CGMs). The inherent attributes of both the cementing matrix and granular packing critically dictate the adhesion behavior and mechanical performance of CGMs. A succession of cement grout flow tests was conducted to elucidate the influence of particle size and the SCCG flowability on SCCG adhesion mechanism within granular packing. Furthermore, the influence of particle size and the cementing matrix volume on the mechanical characteristics of CGMs was scrutinized via uniaxial compressive testing. The results illuminate that the adhesion behavior of SCCG within granular packing is predominantly dependent on the yield stress of SCCG and the average particle size. Additionally, it is established that the peak strength of CGMs is intimately intertwined with the cementing matrix volume and the average particle size, as corroborated by a substantial aggregate of 135 uniaxial compression tests.