Cotton aphid (Aphis gossypii Glover) is a harmful pest that affects cotton crops in Xinjiang, China. Afidopyropen is a new type of insecticide that exerts a strong control effect on piercing-sucking pests. In this work, Highperformance liquid chromatography (HPLC) was used to assess afidopyropen residues on different cotton parts following foliar spraying and root application. The effects of agent retention on physiological indices of cotton aphids and preventive effects were investigated. The results showed that different application methods had a strong influence on afidopyropen residues, most of which were in cotton roots, with fewer in stems and leaves. Enzyme activity analysis showed that the carboxylesterase activity of A. gossypii was significantly increased under different application methods. Foliar spraying and root application (hydroponics) of afidopyropen had rapid, potent effects against A. gossypii, while root application (soil cultivation) did not have a significant effect, but had a positive effect by day 14. Elucidation of the effects of the two application methods to the physiological indices and control of A. gossypii provide a theoretical basis for the development and promotion of integrated water-pharmaceutical technologies for afidopyropen spraying and drip irrigation in cotton fields in Xinjiang and elsewhere.

The environmental impact of red mud leachate, particularly from tailings ponds, has become a significant concern due to its highly alkaline nature and potential to cause widespread soil and water contamination. Addressing this issue requires effective strategies for mitigating the leakage of contaminants, such as heavy metals and hazardous alkalis, into surrounding ecosystems. This study explores the use of fly ash-modified clay liners as a solution to contain and treat red mud leachate pollutants, including heavy metals and alkalis. Macro-scale tests, such as permeation and unconfined compression tests, combined with micro-scale analyses (XRD, SEM, BET), investigate the influence of varying fly ash content on the hydraulic conductivity, mechanical properties, and microstructure of the clay liners. The findings show that fly ash significantly reduces the hydraulic conductivity of the liners, improving their effectiveness in preventing seepage. It also enhances the liners' ability to adsorb heavy metal ions and increases their mechanical strength, especially cohesion, with optimal performance at a 9 % fly ash content. The study further reveals that pozzolanic reactions in the alkaline environment of red mud lead to the formation of cementitious gel binders (C-S-H, C-A-H), which reduce pore sizes and create a denser, more impermeable structure. These improvements in both physical and chemical stability demonstrate the potential of fly ash-modified clay liners as an effective, sustainable solution for managing red mud tailings ponds. This study provides valuable support for environmental management of red mud tailings ponds and the sequestration of red mud leachate waste.

Solar radiation in plateau permafrost regions is strong. The asphalt pavement strongly absorbs and slowly dissipates heat, leading to significant heat accumulation on the pavement. This accumulation disturbs the underlying permafrost and eventually causes serious pavement damage. To improve the heat resistance and dissipation capabilities of asphalt pavement, a nanofluid directional heat conduction structure (N-DHCS) was suggested and analyzed in this paper. The designed structure can resist heat in the daytime due to the low thermal conductivity of liquid and dissipates heat at night through natural convection. The finite element method and laboratory irradiation experiment were employed to performed thermal analyses of N-DHCS. The results demonstrated that establishing the N-DHCS in asphalt pavements can enhance active heat dissipation capacity, which is beneficial for protecting the frozen soil in plateau permafrost regions.

Observations by the Lunar Prospector and the Lunar Atmosphere and Dust Environment Explorer spacecraft suggest the existence of a near-global deposit of weakly bound water ice on the Moon, extending from a depth of a decimetre to at least three metres. The existence of such a layer is puzzling, because water ice would normally desorb at the prevailing temperatures. We here determine the conditions for long-term thermal stability of such a reservoir against solar and meteoroid-impact heating. This is done by using the highly versatile thermophysics code nimbus to model the subsurface desorption, diffusion, recondensation, and outgassing of water vapour in the porous and thermally conductive lunar interior. We find that long-term stability against solar heating requires an activation energy of similar to 1.2 eV in the top metres of lunar regolith, and a global monthly night time exospheric freeze out amounting to similar to 1 tonne. Furthermore, we find that a lower similar to 0.7 eV activation energy at depth would allow for water diffusion from large (0.1-1 km) depths to the surface, driven by the radiogenically imposed selenotherm. In combination with solar wind-produced water, such long-range diffusion could fully compensate for meteoroid-driven water losses. These results are significant because they offer quantitative solutions to several currently discussed problems in understanding the lunar water cycle, that could be further tested observationally.

BackgroundThe dynamic coupled hydro-thermo-mechanical behavior of the unlined structure in saturated porous structure under extreme geotechnical and geology engineering (e.g., underground explosion, laser thermal rock breaking) have aroused extensive research interests on the constitutive modeling and transient dynamic responses prediction. Although the current fractional-order hydro-thermo-mechanical models have been historically proposed, the theoretical formulations still adopt the classical fractional derivatives with singular kernels, and the inherent strain relaxation effect and the associated memory dependency remains not considered yet in such complex condition.PurposeTo compensate for such deficiencies, the current work aims to establish the new hydro-thermo-mechanical model by introducing the Atangana-Baleanu (AB) and Tempered-Caputo (TC) fractional derivatives with non-singular kernels.MethodsThe proposed model is applied to investigate transient structural dynamic hydro-thermo-mechanical response of a cylindrical unlined tunnel in poroelastic medium by applying Laplace transformation approach.ResultsThe influences of the AB and TC fractional derivatives on the wave propagations as well as the dimensionless responses of the temperature, displacement, stress, and pore-water pressure are evaluated and discussed.ConclusionThe non-singular AB and TC fractional derivatives slower the thermal wave propagation. In addition, the dimensionless pore water pressure dissipation is maximally reduced. The increase of strain relaxation time parameter reduces the mechanical dynamic response regions and eliminates the sharp jumps of mechanical response at the elastic wave front, which are consistent with continuity of displacement in real engineering situations.

Artificial ground freezing (AGF) is a ground improvement technique enabling the construction of underground structures in challenging geological conditions. After constructing an underground structure within the groundice cofferdam, the soil undergoes a thawing process that can impact the structure stability and waterproofing properties of the lining. Minimizing or preventing potential damage, as well as avoiding delays in construction, can be achieved through a rational design of thawing regimes. In this paper, we present a semi-analytical model for the thermal behavior of ice-wall during its natural or artificial thawing. The process is described by three independent one-dimensional mathematical problems: the thawing of the outer surface of the ice wall, the thawing of its inner surface, and the thawing of soils around the freeze pipes (in the case of artificial thawing). The proposed approach facilitates the calculation of natural and artificial thawing times and the power required for artificial thawing. The efficiency of the model is demonstrated by comparison with numerical simulation results. This makes the approach suitable and desirable for engineering practice. Importantly, the model allows for seamless analysis of several combinations of influencing factors to select thawing parameters aligned with the requirements of different construction projects.

Lakes on the Qinghai-Tibet Plateau (QTP) have notably expanded over the past 20 years. Due to lake water level rise and lake area expansion, the permafrost surrounding these lakes is increasingly becoming submerged by lake water. However, the change process of submerged permafrost remains unclear, which is not conducive to further analyzing the environmental effects of permafrost change. Yanhu Lake, a tectonic lake on the QTP, has experienced significant expansion and water level rise. Field measurement results indicate that the water level of Yanhu Lake increased by 2.87 m per year on average from 2016 to 2019. Cold permafrost, developed in the lake basin, was partially submerged by lake water at the end of 2017. Based on the water level change and permafrost thermal regime, a numerical heat conduction permafrost model was employed to predict future changes in permafrost beneath the lake bottom. The simulated results indicate that the submerged permafrost would continuously degrade because of the significant thermal impact of lake water. By 2100, the maximum talik thicknesses could reach approximately 7, 12, 16, and 19 m under lake-bottom temperatures of +2.0, +4.0, +6.0, and +8.0 degrees C, respectively. Approximately 291 years would be required to completely melt 47 m of submerged permafrost under the lake-bottom temperature of +4 degrees C. Note that the permafrost table begins to melt earlier than does the permafrost base, and the decline in the permafrost table occurs relatively fast at first, but then the process is attenuated, after which the permafrost table again rapidly declines. Compared to climate warming, the degradation of the submerged permafrost beneath the lake bottom occurred more rapidly and notably.

Asa calculation method based on the Galerkin variation, the numerical manifold method (NMM) adopts a double covering system, which can easily deal with discontinuous deformation problems and has a high calculation accuracy. Aiming at the thermo-mechanical (TM) coupling problem of fractured rock masses, this study uses the NMM to simulate the processes of crack initiation and propagation in a rock mass under the in fluence of temperature field, deduces related system equations, and proposes a penalty function method to deal with boundary conditions. Numerical examples are employed to con firm the effectiveness and high accuracy of this method. By the thermal stress analysis of a thick-walled cylinder (TWC), the simulation of cracking in the TWC under heating and cooling conditions, and the simulation of thermal cracking of the Swedish & Auml;sp & ouml; Pillar Stability Experiment (APSE) rock column, the thermal stress, and TM coupling are obtained. The numerical simulation results are in good agreement with the test data and other numerical results, thus verifying the effectiveness of the NMM in dealing with thermal stress and crack propagation problems of fractured rock masses. (c) 2024 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting 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/).

Temperature changes affect the nonlinear consolidation process in soils, and there is limited associated theoretical research. In this study, the governing equations for nonlinear consolidation and thermal conduction are developed, and a mathematical model for one-dimensional nonlinear thermal consolidation in saturated clay under the impeded drainage boundary is established, where the temperature-dependent compressibility and permeability are considered. Meanwhile, the finite-difference solutions for nonlinear consolidation and the analytical solutions for thermal conduction are obtained, respectively. Furthermore, the proposed model's reasonableness is verified by comparison with other theoretical models. Based on this, the impact of several factors on nonlinear thermal consolidation behaviors is investigated. With a rise in temperature increment (Delta T), the dissipation rate of excess pore water pressure (EPWP) accelerates in the later consolidation stage, and the final settlement becomes larger. In addition, the EPWP dissipation rate grows remarkably with an increasing impeded drainage boundary parameter (mu). In particular, the impeded drainage boundary can be degraded into a drainage boundary when the value of mu becomes large (e.g., mu = 100 m-1). Increasing preconsolidation pressure (pcR) results in a reduction in settlement, and the maximum values of EPWP decline with a rising linear loading time (tc). Overall, this study contributes to the accurate prediction of the nonlinear consolidation process taking the thermal effect into account. This study might provide a basis for the analysis of soil consolidation features in geotechnical projects that involve thermal effects, which have been growing in number in recent decades. For instance, an approach that combines thermal treatment with surcharge preloading has started to be employed for soft soil reinforcement. When this method is used in practical engineering projects, the changes in EPWP and settlement can be predicted based on the model developed in this study. In addition, this study reveals that increasing the temperature by 60 degrees C can lead to an increase in the final settlement of saturated clay by approximately 25%, compared with ambient temperature treatment. Besides, compacted clay, which typically serves as a bottom engineering barrier, might be subject to consolidation deformation due to varied temperatures and external loading. The model presented could contribute to properly predicting the porosity change in compacted clay under this scenario.

Most lakes on the Qinghai-Tibet Plateau have expanded in recent years. Zonag lake, a critical habitat for Tibetan antelopes in the continuous permafrost zone, burst and overflowed after several years of expansion, resulting in a reduction of approximately 100 km(2) in the lake area. Observations have revealed new permafrost is forming on the exposed bottom, accompanied by various periglacial landscapes. The permafrost aggradation on the exposed bottom is rapid, and the permafrost base reached 4.9 m, 5.4 m, and 5.7 m in the first three years, respectively. In this study, the future changes and influencing factors of recently formed permafrost are simulated using a one-dimensional finite element model of heat flow. The simulated results indicate that the permafrost on the exposed bottom is likely to continue to develop, appearing first quick back slow trend. Besides the surface temperature, the annual amplitude is also an important factor in affecting the aggradation of permafrost. The unidirectional permafrost aggradation in the study area is different from the bidirectional permafrost aggradation on the closed taliks around the Arctic. Additionally, snow cover and vegetation are two important factors influencing the future development of permafrost on the exposed lake bottom.