Desertsand concrete (DSC) is a sustainable alternative to natural river sand; however, its application in cold regions is restricted by inadequate crack resistance and freeze–thaw durability. This study investigates the freeze–thaw performance of steel–polypropylene hybrid fiber-reinforced desert sand concrete (SPHF-DSC), with emphasis on durability enhancement and service life prediction. A three-factor, three-level orthogonal experimental design was employed to evaluate the effects of desert sand replacement ratio (DSR), steel fiber (SF) content, and polypropylene fiber (PPF) content on mass loss, relative dynamic elastic modulus, and compressive strength under 25–100 freeze–thaw cycles. The results demonstrate that hybrid fiber reinforcement significantly improves freeze–thaw resistance due to the synergistic interaction between SF and PPF. After 100 cycles, the mass loss of all specimens remained within a narrow range of 0.65% to 0.73%, and the relative dynamic elastic modulus retention stayed above 90%. The optimal mixture (DSR = 30%, SF = 2%, PPF = 0.05%) exhibited superior frost resistance with the lowest deterioration indices among all groups. A freeze–thaw damage model based on damage mechanics was established and validated ($R^2$ > 0.96), enabling prediction of a service life exceeding 38 years under typical cold-region climatic conditions. These findings provide a durability-oriented design reference for the engineering application of DSC in cold-region infrastructure. Furthermore, the utilization of local desert sand reduces transportation energy consumption and promotes the sustainable development of energy infrastructure.

Background: This study explored the influence of milk fat on non-enzymatic glycation of proteins and protein digestibility by analyzing the accumulation of glycation products and changes in protein structure. Results: The contents of POV and MDA increased significantly on day 7 of storage in milk model groups with different milk fat concentrations (0, 2, 4, 6%) and the increase was more obvious in the high-fat (6%) group. In the high-fat group, the contents of glyoxal and methylglyoxal, the intermediate products of non-enzymatic glycation increased at a high level. The peak shift and the appearance of new peaks in the infrared spectrum further indicated enhanced glycation coupled with lipid oxidation. In addition, the decrease in fluorescence intensity, the increase in ultraviolet absorption, the reduction in surface hydrophobicity, and the change of protein secondary structure in the high fat group indicated obvious changes in the microstructure of proteins. The cleavage site of protease was reduced because of the alterations in protein advanced structure and the occupation of amino acids digestion sites, which subsequently reduced the digestibility of proteins. This phenomenon was more obvious in the early stage of gastrointestinal digestion. Conclusion: High levels of milk fat promoted non-enzymatic glycation by accelerating lipid oxidation, which in turn induced glycation, cross-linking, and aggregation of milk proteins. These structural changes further hindered the action of digestive enzymes, ultimately reducing the digestibility of milk proteins.

Channel erosion and sediment entrainment amplify rainstorm-triggered debris flows, but their interaction with topographic constraints remains poorly quantified. To reveal the controlling mechanism of erosion amplification on the disaster-forming process of rainstorm-type debris flows, using the 2016 Zhangba Xiaosha River event in Yunnan, China, we reconstructed debris-flow motion, erosion, and deposition with RAMMS::DEBRISFLOW. Five bed-erosion scenarios (0, 0.25, 0.50, 0.75 and 1.0 m) were used to assess changes in deposit thickness, runout, velocity, impact pressure, and volume amplification. The 1.0 m baseline scenario successfully reproduced the observed path, depositional extent, and representative deposit thickness. Increasing the equivalent erosion depth from 0 to 1.0 m increased the total debris-flow volume from 2.0 × 10⁴ to 4.27 × 10⁴ m³, yielding an amplification factor of 2.14; without erosion, maximum runout was 44.2% shorter. Along-channel erosion supply increases the mass, flow depth and momentum of the moving mass, forming an amplification chain of “sediment supply−scale amplification−momentum maintenance−frontal propagation”. Feedback may exist between actual erosion intensity, flow velocity and flow depth, but the equivalent erosion depth in RAMMS scenarios in this study is a predefined parameter. Topography exerted reach-specific controls: steep upstream channels promoted initiation and acceleration, the middle reach dominated erosional bulking, and the wider, gentler downstream reach enhanced dissipation and deposition. Within the erosion scenarios of 0.75–1.0 m set in this study, when the equivalent erosion depth increased further, the newly entrained sediment mainly increased deposit thickness and inundation extent, while the increment of maximum runout distance was limited. The event disaster scale resulted from coupled erosion-induced amplification and longitudinal topographic constraints. Hazard assessments should integrate initial initiation volume, erodible channel sediment, and local reach-scale topography.