Understanding the carbohydrate dynamics of sprouting Cirsium arvense (L.) Scop. and Sonchus arvensis L. ramets can assist in optimizing perennial weed management. However, detailed knowledge about general reserve dynamics, minimum values in reserves (compensation point) and different reserve determination methods remains sparse. We present novel insights into reserve dynamics, which are especially lacking for S. arvensis. We uniquely compare root weight changes as a proxy for carbohydrates with direct carbohydrate concentration measurements using high-performance liquid chromatography (HPLC). In a greenhouse study, ramets of two sizes (20 and 10 cm) were planted in pots. Subsequent creeping roots of sprouted plants were destructively harvested and analyzed for carbohydrates 12 times between planting and flowering. Efficiency in storing carbohydrates and the replenishing rate of root weight and carbohydrates was much higher in S. arvensis than in C. arvense. Thus, our study urges to evaluate perennial weed species individually when investigating root reserves. Determining root reserves by either using root weight changes as a proxy for carbohydrates or directly measuring carbohydrate concentrations by HPLC differed in the minimum values of reserves referred to as compensation points. For both species, these minimum values occurred earlier based on root weight than based on carbohydrate concentrations. Cutting ramets into 20 or 10 cm sizes did not significantly affect carbohydrate concentration or root weight changes for both species. We conclude that any practical applications targeting perennial weeds by fragmenting roots into small ramets through belowground mechanical control must be evaluated for trade-offs in soil structure, soil erosion, and energy consumption.

Polymer-coated controlled-release fertilizers (PC-CRFs) are valued for nutrient efficiency, but concerns remain about the long-term impacts of their plastic coatings on soil health. This study investigates the physicochemical characteristics of two commercially available PC-CRFs, type A and B, and their changes during nutrient release. Accelerated nutrient release experiments were conducted for 25 d in ultrapure water (free water) and saturated soil with five wet-dry cycles. Total phosphorus and total nitrogen release were measured, with lower concentrations found in soil column effluent compared to water. Additionally, studying microplastic (MP) release from type A PC-CRFs during nutrient release showed that a significantly greater number of MPs were released in the soil column than in water. The results also indicated a preferential migration of smaller MPs to the deeper layers of the soil column. Microscopic pores and cracks were observed through surface morphology analysis, likely caused by osmotic pressure during nutrient release, potentially contributing to MP generation. Mechanical degradation of the type A PC-CRF microcapsules was assessed through surface wear and shear tests to simulate the forces exerted by soil particles and agricultural machinery. Our results showed that longer surface wear duration increased the number of generated MPs, while higher loading in surface wear experiments resulted in a larger median diameter of the MPs.

The behavior of ice particles impacting against a rigid surface is a topic that has gained more and more relevance in the field of transportation safety, particularly in the automotive and aerospace sectors. The present review outlines the various controlled experimental approaches used to study artificial ice particle collisions, describing the setup configurations, particle release mechanisms, and the selection of materials for impact surfaces. It also assesses fundamental studies that measure the coefficient of restitution (CoR or en) and the fragmentation regime of ice upon impact, clarifying how ice particles react when they strike a surface. The review also includes analytical and empirical formulas that describe the critical impact velocity, which determines the different impact outcomes, like bouncing, sticking, or fragmentation and fragmentation distribution of the ice particles. Lastly, it summarizes how particle size, temperature, and material properties affect the impact responses. In addition, the review proposes a visual representation of the different models and how they compare. The visual representation highlights the differences between each model and the transition from elastic to plastic impact responses, and it is instrumental in understanding the conditions under which ice particles leave a residual mass on the impact surface. The insights gained from this review are vital for better understanding the impact of the ice particle phenomenon and mapping the state of the art in this branch of research.

With the rapid development of infrastructure construction on oceanic reefs, calcareous sand, as the primary medium of these reefs, exhibits unique physical and mechanical properties such as high void ratio, low strength, and susceptibility to particle breakage. These characteristics reduce the bearing capacity and stability of pile foundations in calcareous sand foundations. This study investigates the bearing characteristics of high-strength preloaded expansion piles in calcareous sand foundations, taking into account the influence of HSCA high-performance expansion agent dosage through a series of indoor model tests and in-situ tests. The research delves into the load-settlement curves of expansion piles, the distribution of axial force and side resistance of piles, and the effects of Calcareous sand compaction and reinforcement around the piles. The results indicate that adding the HSCA high-performance expansion agent results in compaction preloading of the Calcareous sand around the pile, significantly increasing the expansion stress on the pile side, thereby enhancing the resistance on both the pile side and pile tip. When the expansion agent dosage is 20%, the ultimate bearing capacity can be increased by 56%, and the ultimate side resistance by 63%. The Coulomb strength theory of non-cohesive soil is employed to accurately calibrate the incremental side resistance of the expansion section. A prediction model for the bearing capacity of the expansion pile is established by combining the side resistance prediction model with the ultimate side resistance load-sharing ratio. The research outcomes provide important guidance for the optimization, design, and construction of high-strength preloaded expansion piles in calcareous sand foundations.

The soil's creep characteristics significantly impact both the effectiveness of the support system and the enduring stability of the engineering structure. During construction, dewatering is often carried out, which results in seepage within highly permeable soils. To scrutinize the creep behavior of silty fine sand under seepage conditions, triaxial compression tests and triaxial creep tests were conducted on the silty fine sand, subject to three distinct seepage flow rates: 0.5 ml/min, 1.0 ml/min, and 1.5 ml/min. The test results indicate that seepage reduces the maximum stress capacity of the soil and increases its creep deformation. Particularly under relatively high deviatoric stress and seepage flow rates, the specimens exhibit three stages: transient creep, stationary creep, and acceleration creep. Notably, the axial creep deformation rate shows a positive correlation with both seepage flow rates and deviatoric stress. Concurrently influenced by seepage and creep, fine particles within the specimen accumulate in the central and upper regions, whereas the lower is characterized by larger particles. The progressive increase in pore water pressure, intricately linked to the impeding effect of fine particles on permeation pathways, catalyzes the creep-induced deformation of the specimen. Based on the experimental results, a modified Burgers model has been established. This model takes into account seepage, sliding damage, and particle fragmentation. A comparative analysis, contrasting the modified Burgers model against calculated values derived from the traditional Burgers and Kelvin-Voigt models, underscores the effectiveness of the proposed model. Specifically, the modified Burgers model adeptly captures the transient creep, stationary creep, and acceleration creep stages of silty fine sand, especially under varying seepage flow rates.

Management of perennial weeds has become increasingly difficult with the reduction of herbicide use. Creeping perennials accumulate reserves in specialized belowground organs from which they regenerate new plants after a disturbance. Through tool selection, tillage operations could be optimized to reduce perennial-weed reserves and limit regeneration. In the present study, the effect of five tools on the fragmentation of the creeping roots of Cirsium arvense (L.) Scop. (Canada thistle), a major perennial weed in arable crops, were analysed. A field trial was set up to measure the lengths of the root fragments left after tillage. Five tools were tested: mouldboard ploughing, rotary harrow, disc harrow, rigid-tine cultivator and goose-foot cultivator. Fragment-length distribution varied according to the tool: rotary harrow left the smallest (3.7 cm on average) and least variable fragment lengths, mouldboard ploughing the longest (12.7 cm) and most variable ones. The other tools produced intermediate-sized fragments (8-10 cm). Based on these results and literature, a model was proposed to predict perennial-weed regeneration probability from storage-organ fragments after one tillage run. The effects of six factors, which were agronomic (tillage tool), environmental (soil conditions and temperature) and biological (storage-organ fragment diameter, maximal belowground-shoot length and pre-tillage storage-organ distribution), were tested through a sensitivity analysis. According to the model, the probability of fragment regeneration success is lower for the rotary harrow than for the mouldboard plough. The most important drivers of fragment regeneration success were the biological traits: fragment diameter and maximal belowground-shoot length per unit fragment biomass. The present model should be complemented to predict the effect of tillage on perennial-weed regrowth and help improving non-chemical weed-management strategies. To achieve this, further research is needed on plant regrowth potential from storage organs and their architecture in the soil.

To optimize the excavation of rock using underground blasting techniques, a reliable and simplified approach for modeling rock fragmentation is desired. This paper presents a multistep experimentalnumerical methodology for simplifying the three-dimensional (3D) to two-dimensional (2D) quasiplane-strain problem and reducing computational costs by more than 100-fold. First, in situ tests were conducted involving single-hole and free-face blasting of a dolomite rock mass in a 1050-m-deep mine. The results were validated by laser scanning. The craters were then compared with four analytical models to calculate the radius of the crushing zone. Next, a full 3D model for single-hole blasting was prepared and validated by simulating the crack length and the radius of the crushing zone. Based on the stable crack propagation zones observed in the 3D model and experiments, a 2D model was prepared. The properties of the high explosive (HE) were slightly reduced to match the shape and number of radial cracks and crushing zone radius between the 3D and 2D models. The final methodology was used to reproduce various cut-hole blasting scenarios and observe the effects of residual cracks in the rock mass on further fragmentation. The presence of preexisting cracks was found to be crucial for fragmentation, particularly when the borehole was situated near a free rock face. Finally, an optimization study was performed to determine the possibility of losing rock continuity at different positions within the well in relation to the free rock face. (c) 2024 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).

Coral reef limestone is a unique type of rock and soil body characterized by high porosity. Its dynamic mechanical properties under impact loads differ significantly from those of conventional land-sourced aggregate concrete.This study utilizes coral reef limestone as both coarse and fine aggregates to prepare C40 strength concrete. The research investigates the effects of dry-wet carbonation cycles on its dynamic mechanical behavior and energy evolution characteristics using a Split Hopkinson Pressure Bar (SHPB) mechanical testing system.The findings reveal that increasing the number of dry-wet carbonation cycles leads to a significant weakening of the internal structural bonding in coral reef limestone concrete. Notably, the degree of phenolphthalein color change diminishes, while uniaxial compressive strength and tensile strength demonstrate an overall downward trend. The reduction in tensile strength is less pronounced than the decrease in compressive strength. Additionally, the relative dynamic elastic modulus gradually decreases, and a size effect is noted, with a rapid acceleration in mass loss. As the number of dry-wet carbonation cycles increases, dynamic compressive strength declines, and failure modes shift from surface cracking to crush-type failure.The dynamic increase factor (DIF) of the coral reef limestone concrete indicates a high sensitivity to strain rate, with a significant rise in DIF value as the strain rate increases. Various energies generated under impact load exhibit clear strain rate effects. Furthermore, the effects of dry-wet carbonation cycling enhance energy dissipation, especially at 30 cycles, where energy dissipation increases sharply, while a hindering effect on transmitted energy is observed.

The conversion of natural areas into agricultural land has increased human-wildlife interactions, often resulting in crop damage. This study focuses on the white-lipped peccary (Tayassu pecari), which thrives in landscapes where well-preserved, naturally-vegetated public and private lands are juxtaposed with agricultural fields. We investigated the habitat use and selection of four herds of white-lipped peccaries in a landscape mosaic along the southern border of Emas National Park in the Cerrado biome of Brazil. Our findings reveal that white-lipped peccaries prefer both corn plantations and gallery forests as habitats. Through high-frequency GPS telemetry, we observed a strong tendency to turn when herds were in agricultural areas and gallery forests, indicating feeding behavior. On the other hand, they typically move in straight lines for long distances when traversing bare soil fields and native Cerrado vegetation, suggesting they are merely passing through these habitats. The extensive feeding on corn crops in agricultural fields has resulted in significant financial losses for producers, leading to a conflict between white-lipped peccaries and landowners. Understanding the movement dynamics of the species and their intensive use of both private and public lands can aid in the development of management strategies that minimize or eliminate crop losses while ensuring the survival of this vulnerable species in landscapes comprising agricultural fields and native habitats.

The particle crushing effect of coarse-grained soil has been widely studied. This study conducted lateral compression tests under high-pressure conditions to study the compression characteristics and particle crushing laws of waste particles from tunnel excavation of phyllite. Samples with continuous and intermittent gradation were set up to analyze the physical parameters such as compression deformation law, gradation curve, crushing index, and plastic work before and after loading. The results show that the strain of each group of samples increases rapidly with stress during the loading process and then gradually stabilizes. The continuous group gradation shows good compressive bearing capacity. As the content of phyllite particles decreases, the overall deformation of the samples can be effectively reduced. Under high stress, the grading of each intermittent grading sample gradually converges to a continuous grading, with similar physical and mechanical properties. The fragmentation indicators applicable to the particles of waste rock in phyllite are Br and Bg. Establishing a hyperbolic model to fit the plastic work and relative fragmentation rate Br during the compression process, it was found that fitting the plastic work model can better characterize the fragmentation law of waste particles in phyllite. The research results can provide certain reference and guidance for further understanding the compression characteristics and particle fragmentation laws of soft rock waste materials such as phyllite, as well as for the filling of geotechnical engineering structures.