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The influence of water–rock interaction in the process of coal mine construction cannot be ignored, especially when the groundwater quality is complex and contains acidic substances. In this paper, considering the influence of mining, blasting, and earthquake, the dynamic mechanical properties and fractal characteristics of sandstone under acid dry–wet cycle were studied. A comprehensive method combining X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectrometer mapping (EDS Mapping) technology for chemical damage analysis was established, and the damage mechanism of sandstone was summarized. The test results show that the acid dry–wet cycle has a great influence on the dynamic peak stress of sandstone (σd) and elastic modulus (Ed) is higher than neutral. And with the decrease of pH value of acidic solution, σd and Ed decrease and the peak strain increases, indicating that the acid solution has corrosion and softening effect on sandstone. With the increase of acid dry–wet cycles, the fractal dimension increases linearly. Sandstone fragments show more broken blocks and smaller particle sizes. Microscopic comprehensive analysis shows that acid solution (H2SO4) will preferentially react with metal oxides and salt cements to open rock pores, and gypsum (CaSO4) and other products will be formed in the process. In the process of the acid dry–wet cycle, the sandstone is corroded by acid solution, which leads to pore growth. Meanwhile, the dry–wet cycle causes repeated expansion and contraction of rock particles. Both of them accelerate rock failure.HighlightsAcid solution weakens the dynamic mechanical parameters of rock, softens the specimen and increases the post-peak strain. With the increase of cycles, the fractal dimension of sandstone increases linearly, and the lower the pH, the more fragmentation and the smaller the particle size.The damage caused by the acid dry-wet cycle to the rock consists of two parts: physical and chemical.

Chemical corrosion has significant impact on the properties of rock materials. To investigate the effect of chemical corrosion on the porosity and mechanical properties of sandstones, the nuclear magnetic resonance (NMR) technique was used for the measurement of porosity. Uniaxial compression tests were then conducted for rock specimens treated with chemical corrosions. The test results showed that, compared with the rock specimens in their natural state, after chemical corrosions, the porosity increased, the uniaxial compressive strength and elastic modulus of sandstone both decreased, but the corresponding peak strain increased. A chemical damage variable derived from the change of porosity and the effective bearing area of rock samples was proposed. Based on the chemical damage variable, the corrosion order of different chemical solutions on sandstone was obtained as H2SO4 > NaOH > distilled water. The mechanism of chemical corrosion was also explored based on water-rock reactions. Finally, by introducing the compaction coefficient, an improved statistical damage constitutive model was established to describe the damage evolution of the sandstones treated with different chemical corrosions.

The mechanical properties of rocks are significantly affected by chemical corrosion. To explore the influence of chemical corrosion on the weakening laws of sandstone mechanical properties, the porosity and pore size distribution (PSD) of sandstone samples immersed in different chemical solutions was measured by the nuclear magnetic resonance (NMR) technique. The damage variable based on the change of porosity was proposed to analyse the chemical damage to the sandstone samples. Moreover, both compressive and Brazilian tensile tests under static and dynamic conditions were carried out using a conventional servo-controlled testing machine and a split Hopkinson pressure bar (SHPB) system. The results showed that the porosity and proportion of macropores of the sandstone increase after chemical corrosion. The weakening laws of compressive and tensile strength of the sandstone under static and dynamic states are similar, and the relations among them and the damage variable are exponential. The dynamic tensile strength is most sensitive to the effects of chemical corrosion. The order of the degree of damage of chemical solutions on mechanical properties of sandstone is: DH2SO4 > DNaOH > DDistilledwater. Based on the experimental data, the relationships between the mechanical properties and chemical damage variable can be described as exponential equations. Additionally, the variations of dynamic increase factors versus chemical damage variable, the relationship between PSD and the strength of the chemically corroded sandstone, and the corrosion mechanism are also investigated.

In this investigation, two different varieties of ‘Prada’ limestones were studied: a dark grey texture, bearing quartz, clay minerals, organic matter and pyrites, and a light grey texture with little or no presence of such components. We have observed two effects of different intensity when heating the dark texture from 400 °C: (1) the explosion of certain samples and (2) greater thermal damage than in the light grey texture. Chemical and mineralogical composition, texture, microstructure, and physical properties (i.e. colour, open porosity, P and S-wave velocity) have been evaluated at temperatures of 105, 300, 400, and 500 °C in order to identify differences between textures. The violence of the explosive events was clear and cannot be confounded with ordinary splitting and cracking on thermally treated rocks: exploded samples underwent a total loss of integrity, displacing and overturning the surrounding samples, and embedding fragments in the walls of the furnace, whose impacts were clearly heard in the laboratory. Thermogravimetric results allowed the identification of a process of oxidation of pyrites releasing SO2 from 400 °C. This process jointly with the presence of microfissures in the dark texture, would cause a dramatic increase in pore pressure, leading to a rapid growth and coalescence of microcracks that leads to a process of catastrophic decay in rock integrity. In addition to the explosive events, average ultrasound velocities and open porosity showed a greater variation in the dark grey texture from 400 °C. That result also points towards a significant contribution of oxidation of pyrites on the thermo-chemical damage of the rock, among other factors such as the pre-existence of microfissures and the thermal expansion coefficient mismatch between minerals. Implications in underground infrastructure and mining engineering works are critical, as the explosive potential of pyrite-bearing limestones bears risk for mass fracturing and dramatic strength decay from 400 °C. Moreover, SO2 released has harmful effects on health of people and the potential to form acid compounds that corrode materials, shortening their durability and increasing maintenance costs.

Machine-learned potentials (MLPs) have exhibited remarkable accuracy, yet the lack of general-purpose MLPs for a broad spectrum of elements and their alloys limits their applicability. Here, we present a promising approach for constructing a unified general-purpose MLP for numerous elements, demonstrated through a model (UNEP-v1) for 16 elemental metals and their alloys. To achieve a complete representation of the chemical space, we show, via principal component analysis and diverse test datasets, that employing one-component and two-component systems suffices. Our unified UNEP-v1 model exhibits superior performance across various physical properties compared to a widely used embedded-atom method potential, while maintaining remarkable efficiency. We demonstrate our approach’s effectiveness through reproducing experimentally observed chemical order and stable phases, and large-scale simulations of plasticity and primary radiation damage in MoTaVW alloys. Machine-learned potentials are accurate but often lack broad applicability. Here, authors develop a general-purpose neuroevolution potential for 16 metals and their alloys, achieving efficient and accurate predictions of various physical properties.

Abstract Intestinal stem cells (ISCs) are essential for the regeneration of intestinal cells upon radiation or chemical agent damage. As for radiation-induced damage, the expression of AIM2, YAP, TLR3, PUMA or BVES can aggravate ISCs depletion, while the stimulation of TLR5, HGF/MET signaling, Ass1 gene, Slit/Robo signaling facilitate the radio-resistance of ISCs. Upon chemical agent treatment, the activation of TRAIL or p53/PUMA pathway exacerbate injury on ISCs, while the increased levels of IL-22, β-arrestin1 can ease the damage. The transformation between reserve ISCs (rISCs) maintaining quiescent states and active ISCs (aISCs) that are highly proliferative has obtained much attention in recent years, in which ISCs expressing high levels of Hopx, Bmi1, mTert, Krt19 or Lrig1 are resistant to radiation injury, and SOX9, MSI2, clusterin, URI are essential for rISCs maintenance. The differentiated cells like Paneth cells and enteroendocrine cells can also obtain stemness driven by radiation injury mediated by Wnt or Notch signaling. Besides, Mex3a-expressed ISCs can survive and then proliferate into intestinal epithelial cells upon chemical agent damage. In addition, the modulation of symbiotic microbes harboring gastrointestinal (GI) tract is also a promising strategy to protect ISCs against radiation damage. Overall, the strategies targeting mechanisms modulating ISCs activities are conducive to alleviating GI injury of patients receiving chemoradiotherapy or victims of nuclear or chemical accident.

Highlights Examining recovery mechanisms through self-healing polymer–perovskite interactions under chemical/mechanical stress. Proposing a multi-scale protocol combining electrical, morphological, and chemical metrics to quantitatively assess healing efficacy. Establishing a systematic design strategy based on healing stimuli and device integration scenarios, linking molecular features to functional outcomes. Perovskite solar cells (PSCs) have achieved remarkable power conversion efficiencies (PCE) exceeding 27%, while their operational instability under environmental stress (e.g., moisture, heat, mechanical bending) remains a critical barrier to commercialization. Self-healing polymers (SHPs) with dynamic covalent bonds or non-covalent bonds have emerged as an innovative solution to enhance the durability of PSCs through autonomous damage healing. Although SHPs have been proved to be quite promising for enhance the reliability of PSCs, there is still lacking systematic molecular design strategies tailored for practical cooperation SHPs with versatile types of PSCs. Herein, this review systematically organizes the recent research progress of self-healing PSCs from the perspective of application-oriented design principles. The self-healing mechanisms of PSCs using SHPs under chemical and mechanical damage modes are first comprehensively explored, and a multi-dimensional self-healing evaluation system is proposed. Subsequently, the distinct effects of SHPs as additives, interfacial modifiers, and encapsulation materials in PSCs are summarized. More importantly, the incorporation methods of SHPs in PSCs and the structural characteristics of representative SHPs are systematically analyzed, with application-specific design principles for optimized performance proposed. Finally, the challenges and opportunities in the optimization of self-healing material properties, in situ characterization techniques, and scalable fabrication are outlined. This work aims to facilitate the transition of SHP-based self-healing PSCs from laboratory research to real-world applications, providing a roadmap for future developments in this emerging field.

Silicon solar cells are a mainstay of commercialized photovoltaics, and further improving the power conversion efficiency of large-area and flexible cells remains an important research objective 1 , 2 . Here we report a combined approach to improving the power conversion efficiency of silicon heterojunction solar cells, while at the same time rendering them flexible. We use low-damage continuous-plasma chemical vapour deposition to prevent epitaxy, self-restoring nanocrystalline sowing and vertical growth to develop doped contacts, and contact-free laser transfer printing to deposit low-shading grid lines. High-performance cells of various thicknesses (55–130 μm) are fabricated, with certified efficiencies of 26.06% (57 μm), 26.19% (74 μm), 26.50% (84 μm), 26.56% (106 μm) and 26.81% (125 μm). The wafer thinning not only lowers the weight and cost, but also facilitates the charge migration and separation. It is found that the 57-μm flexible and thin solar cell shows the highest power-to-weight ratio (1.9 W g −1 ) and open-circuit voltage (761 mV) compared to the thick ones. All of the solar cells characterized have an area of 274.4 cm 2 , and the cell components ensure reliability in potential-induced degradation and light-induced degradation ageing tests. This technological progress provides a practical basis for the commercialization of flexible, lightweight, low-cost and highly efficient solar cells, and the ability to bend or roll up crystalline silicon solar cells for travel is anticipated. A study reports a combination of processing, optimization and low-damage deposition methods for the production of silicon heterojunction solar cells exhibiting flexibility and high performance.

Organic halides are highly useful compounds in chemical synthesis, in which the halide serves as a versatile functional group for elimination, substitution and cross-coupling reactions with transition metals or photocatalysis 1 , 2 – 3 . However, the activation of carbon–fluorine (C–F) bonds—the most commercially abundant organohalide and found in polyfluoroalkyl substances (PFAS), or ‘forever chemicals’—is much rarer. Current approaches based on photoredox chemistry for the activation of small-molecule C–F bonds are limited by the substrates and transition metal catalysts needed 4 . A general method for the direct activation of organofluorines would have considerable value in organic and environmental chemistry. Here we report an organic photoredox catalyst system that can efficiently reduce C–F bonds to generate carbon-centred radicals, which can then be intercepted for hydrodefluorination (swapping F for H) and cross-coupling reactions. This system enables the general use of organofluorines as synthons under mild reaction conditions. We extend this method to the defluorination of PFAS and fluorinated polymers, a critical challenge in the breakdown of persistent and environmentally damaging forever chemicals. An organic photoredox catalyst system efficiently reduces C–F bonds, generating carbon-centred radicals for hydrodefluorination and cross-coupling reactions, enabling the general use of organofluorines as synthons and breaking down environmentally damaging forever chemicals.

Self-healing is the capability of a material to recover from physical damage. Both physical and chemical approaches have been used to construct self-healing polymers. These include diffusion and flow, shape-memory effects, heterogeneous self-healing systems, covalent-bond reformation and reshuffling, dynamics of supramolecular chemistry or combinations thereof. In this Review, we discuss the similarities and differences between approaches to achieve self-healing in synthetic polymers, where possible placing this discussion in the context of biological systems. In particular, we highlight the role of thermal transitions, network heterogeneities, localized chemical reactions enabling the reconstruction of damage and physical reshuffling. We also discuss energetic and length-scale considerations, as well as scientific and technological challenges and opportunities. Self-healable polymers are materials that recover after physical damage. In this Review, we discuss the physical and chemical approaches to make self-healing polymers, with a focus on similarities with biological systems.