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Assessment of freezing effects on soil requires estimating the soil freezing characteristic curve (SFCC)—the variation of unfrozen water content with temperature. The existing methods for obtaining SFCCs often involve either costly experiments or heuristic inference from water retention data. Here, we propose a pore‐morphology‐based method for simple and efficient estimation of the freezing characteristic curve of water‐saturated porous media, whereby the pore‐scale configurations of water and ice phases are simulated in a digital image of porous microstructure. Idealizing the pore space as a system of overlapping spherical pores, the method simulates the freezing process with the Gibbs‐Thomson equation that can consider freezing‐point depression—a decrease in the freezing point due to spatial confinement—based on thermodynamics. For validation, we apply the proposed method to estimate the SFCC of a field soil for which the experimental freezing characteristics data are available. Results show that even with a digital pore image extracted from a surrogate discrete‐element packing of the soil, the proposed method provides an SFCC very close to the experimental data. Key Points A pore‐morphology‐based method is proposed to estimate the freezing characteristic curve of water‐saturated porous media The Gibbs‐Thomson equation and the sphere insertion method are combined to incorporate freezing point depression The proposed method is validated against experimentally measured freezing characteristic data of a field soil

Freezing temperature parameterization significantly impacts the heat balance at sea‐ice bottom and, consequently, the simulated sea‐ice thickness. Here, the single‐column model ICEPACK was used to investigate the impact of the freezing temperature parameterization on the simulated sea‐ice thermodynamic growth during the MOSAiC expedition from October 2019 to September 2020. It is shown that large model errors exist with the standard parameterization and that different formulations for calculating the freezing temperature impact the simulated sea‐ice thickness significantly. Considering the winter mixed layer temperature, a modified parameterization of the freezing point temperature based on Mushy scheme was developed. The mean absolute error (ratio) of simulating sea‐ice thickness for all buoys reduces from 7.4 cm (4.9%) with the “Millero” scheme, which performs the best among the existing schemes in the ICEPACK model, to 4.2 cm (2.9%) with the new developed scheme. Plain Language Summary The heat transferred from the ocean to the sea‐ice influences the growth and melting of the sea‐ice. Freezing temperature is an essential parameter for calculating the heat transfer. Nevertheless, few studies have attempted to evaluate the impact of different freezing temperature parameterizations on the simulated sea‐ice thermodynamic growth. This study uses observed atmosphere and ocean data to force a single‐column model. Using different methods to calculate the freezing temperature significantly impacts the simulated sea‐ice thickness. After a series of testing and comparisons, we have developed a modified parameterization of freezing temperature that significantly reduces the simulation deviation from the observations. Key Points Different parameterizations of the freezing temperature significantly influence the simulated sea‐ice thickness A modified‐Mushy parameterization method is developed for the freezing temperature, significantly improving ice thickness simulation

The influence of freezing processes and vertical transport of trace gases into the upper atmosphere during deep convection is critical to understanding the distribution of aerosol precursors and their climate effects. We conducted experimental studies inside a walk-in cold room for freely levitating raindrops (drop diameter: 2 mm) using an acoustic levitator apparatus. We investigated the effect of freezing raindrops on the retention of organic species for the first time with silver iodide as the ice-nucleating agent. Quantitative chemical analysis determined the retention coefficient, which is defined as the fraction of a chemical species remaining in the ice phase compared to their initial liquid-phase concentrations. We measured the retention coefficients of nitric acid, formic acid, acetic acid, and 2-nitrophenol as single components. Furthermore, we determined the retention coefficients of these substances as binary mixtures. Our results show the dominance of physical aspects such as drop size and ice shell formation over their chemical counterparts with regard to overall retention for the investigated large drops. Thus, for rain-sized drops, almost everything is fully retained during the freezing process, i.e., retention coefficients close to 1, even for species with low effective Henry's law constants (H*<10-4). An ice shell is formed within 4.8 ms around the drops just after the freezing is initiated. This ice shell formation was found to be the controlling factor for the overall retention of the investigated species, which inhibited any further expulsion of dissolved substances from the drop.

China’s extensive permafrost regions necessitate studying strength changes in frozen soil to ensure structural stability and safety. To quantitatively assess soil mechanics under varying conditions, this paper investigates the silty soil in Northeast China using piezoelectric ceramic testing and triaxial testing of freeze-thaw cycles and freezing conditions. The study explores strength variation patterns and structural change mechanisms of silty soil during these processes and establishes soil strength evaluation indices based on piezoelectric signal energy. The principal findings are: (1) Strength of silty soil decreases parabolically with increasing freeze-thaw cycles, with the initial cycle having the most significant impact, particularly for soil with optimal water content. (2) Lower freezing temperature can effectively improve silty soil’s elasticity modulus, failure strength, and cohesion, with more pronounced improvements observed between − 2 °C and − 5 °C compared to -5 °C to -10 °C, while the internal friction angle shows no clear change pattern. (3) Monitoring signals of smart aggregate are related to the properties of smart aggregate and the tested soil. The strength deterioration index ( defined by signal energy correlates greater than 98% with the failure strength of soil at room temperature. Low water content samples exhibit higher energy vectors under the same conditions. (4) The strength enhancement index defined by signal energy correlates greater than 90% with failure strength of frozen soil. High-frequency signals are more responsive to temperature fluctuations. The aforementioned indices provide invaluable insights with regard to the implementation of piezoelectric ceramic testing technology within the field of geotechnical engineering.

Microbiota analyses are key to understanding the bacterial communities within dairy cattle, but the impact of different storage conditions on these analyses remains unclear. This study sought to examine the effects of freezing at -80°C immediately after collection, refrigeration at 4°C for three days and seven days and absolute ethanol preservation on the microbiota diversity of pooled fecal samples from dairy cattle. Examining 16S rRNA gene sequences, alpha (Shannon, Pielou evenness, observed features and Faith PD indices) and beta (Bray-Curtis, βw and Weighted UniFrac) diversity were assessed. The effects of storage conditions on these metrics were evaluated using linear mixed models and PERMANOVA, incorporating the farm as a random effect. Our findings reveal that 7d and E significantly altered the Shannon index, suggesting a change in community composition. Changes in Pielou evenness for 3d and 7d storage when compared to 0d were found, indicating a shift in species evenness. Ethanol preservation impacted both observed features and Faith PD indices. Storage conditions significantly influenced Bray-Curtis, βw, and Weighted UniFrac metrics, indicating changes in community structure. PERMANOVA analysis showed that these storage conditions significantly contributed to microbiota differences compared to immediate freezing. In conclusion, our results demonstrate that while refrigeration for three days had minimal impact, seven days of refrigeration and ethanol preservation significantly altered microbiota analyses. These findings highlight the importance of sample storage considerations in microbiota research.

To study the influence of freeze–thawing on the organic matter content of Loess Plateau soils, four typical soils of the region, namely, sandy soil, black loessial soil, yellow loamy soil, and cinnamon soil, were selected for this study. The indoor simulation test was used to study the change characteristics of organic matter content under the combined effects of freeze‒thaw cycles, soil water content, and depth. When the water content and depth were the same, the organic matter content of the different soil types showed an increasing trend with the increase in freeze‒thaw cycles, and the relationship between organic matter content and freeze‒thaw cycles could be expressed by a power function. In general, in sandy soil and black loessial soil, the water content at the highest soil organic matter content was 15% and 8%, respectively, under different freeze‒thaw cycles. However, in yellow loamy soil and cinnamon soil, on the whole, the water content was 20% when the organic matter content was the highest in the early stage, but when freeze‒thaw cycles was 15, the water content changed when the organic matter content was the highest to 16% and 8%, respectively. This study can provide some data support and reference for revealing the mechanism of freeze–thaw effect on soil organic matter content changes.

This study investigates how saturation (ranging from < 3% to > 97%), freezing temperature (25 °C to − 40 °C), freezing duration (0–16 h), and the number of freeze–thaw cycles (0–40) influence basalt’s mechanical properties. Uniaxial compression tests were performed, and damage as well as constitutive models were developed to capture the mechanical response. The results reveal that the critical saturation range for freeze–thaw damage in basalt lies between 50.1% and 76.9%. When the freezing temperature ranges between − 10 °C and − 20 °C or the freezing duration extends up to 4 h, damage to the basalt intensifies significantly. There is a threshold effect of freezing temperature and duration, where further lowering of temperature or prolonged freezing does not increase damage once the rock is fully frozen. The impact of repeated freeze–thaw cycles shows diminishing marginal effects, with the rate of degradation slowing over multiple cycles. The proposed constitutive model accurately reflects basalt’s mechanical response under various freeze–thaw scenarios by using Young’s modulus and secant moduli as damage calibration parameters. These findings offer valuable insights into understanding rock degradation in cold-region engineering applications, providing guidance for design and maintenance strategies to mitigate rock instability and structural failures caused by freeze–thaw processes. The research outcomes are particularly relevant for underground cavern excavation, slope stability assessment, tunnel construction, and other rock engineering projects in regions subject to repeated freezing and thawing events.

Herein, ordinary silicate concrete specimens are prepared to study the damage law of a cement-concrete material under the effects of salt erosion and a freeze–thaw environment. NaCl, NaHCO3, and Na2SO4 solutions are separately produced, according to the characteristics of saline soil, to conduct an experimental study on the concrete characteristics during quick salt freezing cycles, and to analyse the changes in its compressive strength, mass loss, and dynamic elastic modulus (DEM) under freeze–thaw cycles. Low-field nuclear magnetic resonance (NMR) and scanning electronic microscopy are used to investigate the change in the microstructure of concrete specimens under salt freeze–thaw cycles (FTCs). The results show the loss in compressive strength, mass, DEM, and NMR spectrum signal increased by 1.5–3 times, 3–5 times, 1.5–2.5 times, and 2–4 times, respectively, for concrete specimens under 50–100 FTCs in 6.8% composite salt solution, in comparison to fresh water. Apparent spalling, decreases in the DEM, and reductions in the compressive strength occur in concrete when increasing the number of salt FTCs. The number of internal cracks in the concrete structure increase under the combined action of salt crystallization, moisture absorption, and freeze–thaw. The changes in the internal microscopic pore volume in concrete structures exhibit the same trend with changes in the macro mechanical properties of concrete. The correlation coefficients between the changes in each peak in the NUR spectrum and the changes in the compressive strength of concrete specimens under FTCs in freshwater or low-concentration salt solutions are both larger than 0.7, calculated using the grey correlation degree method. Therefore, these changes could be used as a potential evaluation index for salt frozen damage to concrete structures.

This report presents the results of dielectric studies in a nitrobenzene–decane critical mixture in the homogeneous liquid, biphasic mesophase, and the solid crystal phase. It focuses on detecting critical effects in the broad surrounding of the critical consolute temperature and pre-melting and post-freezing effects in the solid crystal phase. The strong manifestation of the diameter critical anomaly in the biphasic domain and the Mossotti catastrophe type pre-melting and post-freezing effects in the solid phase are evidenced. Studies include the puzzling low-frequency (LF) domain related to translational processes. The real part of electric conductivity, in LF limit, is well portrayed by the super-Arrhenius-type equation in the homogenous liquid and solid phases. The obtained experimental evidence can be significant for the cognitive progress of the still puzzling melting/freezing canonic discontinuous transition.

The physicochemical combination method (PCCM) is a new integrated method for treating and reusing large volumes of slurry-like mud (MS). To study the effects of freezing–thawing (FT) cycles on the mechanical properties of MS treated by the PCCM, unconfined compression tests (UCTs) and microstructural tests are both conducted on PCCM-treated MS samples with different combinations of FT cycles, initial water contents ( w ei ), and cementitious binder contents ( w c ). The experimental results indicate that the unconfined compressive strength ( UCS ) and the elastic modulus ( E ) of PCCM-treated MS decrease exponentially when the FT cycles increase from 0 to 15. For the PCCM-treated MS samples subjected to 15 FT cycles, the reduction degree of their strength, as well as deformation resistance, is more sensitive to the variation of w c compared to that of w ei . Meanwhile, the UCS and E of PCCM-treated MS samples are higher than those of the corresponding MS samples treated by the conventional cement solidification method (CCSM). The superior resistance to FT cycles of PCCM-treated MS is attributed to the presence of APAM, which not only facilitates the aggregation of soil particles but also enhances the dewatering efficiency of MS. Notably, the E / UCS value of CCSM-treated MS is 1.25 times larger than that of PCCM-treated MS, indicating the application of PCCM can significantly enhance the toughness of the treated MS.