Freeze-thaw Process Research Articles

Humidity-Responsive Amorphous Calcium-Magnesium Pyrophosphate/Cassava Starch Scaffold for Enhanced Neurovascular Bone Regeneration.

Developing a neurovascular bone repair scaffold with an appropriate mechanical strength remains a challenge. Calcium phosphate (CaP) is similar to human bone, but its scaffolds are inherently brittle and inactive, which require recombination with active ions and polymers for bioactivity and suitable strength. This work discussed the synthesis of amorphous magnesium-calcium pyrophosphate (AMCP) and the subsequent development of a humidity-responsive AMCP/cassava starch (CS) scaffold. The scaffold demonstrated enhanced mechanical properties by strengthening the intermolecular hydrogen bonds and ionic bonds between AMCP and CS during the gelatinization and freeze-thawing processes. The release of active ions was rapid initially and stabilized into a long-term stable release after 3 days, which is well-matched with new bone growth. The release of pyrophosphate ions endowed the scaffold with antibacterial properties. At the cellular level, the released active ions simultaneously promoted the proliferation and mineralization of osteoblasts, the proliferation and migration of endothelial cells, and the proliferation of Schwann cells. At the animal level, the scaffold was demonstrated to promote vascular growth and peripheral nerve regeneration in a rat skull defect experiment, ultimately resulting in the significant and rapid repair of bone defects. The construction of the AMCP/CS scaffold offers practical suggestions and references for neurovascular bone repair.

Effect of freeze-thawing, cell collection, and laser irradiation cycles on mosaicism occurrence in preimplantation genetic testing for aneuploidy

ObjectiveIn preimplantation genetic testing for aneuploidy, opinions regarding the handling of mosaic embryos vary. In this study, we aimed to investigate the effects of freeze-thawing, the number of cells obtained, and the number of laser irradiation cycles on the degree of embryonic mosaicism. Study designThis study was conducted in three parts. First, we classified specimens into the normal biopsy (control) (119 patients, 304 blastocysts) and thawed-biopsy (TB group) (26 patients, 72 blastocysts)) groups. The control and TB groups were then classified into three categories (euploidy, mosaic and aneuploidy) according to next-generation sequencing (NGS) results, and the number of cells collected and laser irradiation cycles were compared for each category. Subsequently, the effects of differences in the number of cells collected and laser irradiation cycles on NGS results were investigated in the control and TB groups. Finally, data on cell collection and laser irradiation cycles and NGS analysis results for the groups were compared. ResultsThe TB group had a significantly higher incidence of chromosomal mosaicism than the control group. Neither the number of cells collected nor the laser irradiation cycles affected the percentage of chromosomal mosaicism. However, the freeze–thaw process increased the occurrence of mosaicism. ConclusionsThis study showed that repeated freeze–thaw cycles increase the incidence of mosaicism, but the embryos are not aneuploid and are therefore suitable for transfer.

Enhancing freeze-thaw tolerance in baker's yeast: strategies and perspectives.

Frozen dough technology is important in modern bakery operations, facilitating the transportation of dough at low temperatures to downstream sales points. However, the freeze-thaw process imposes significant stress on baker's yeast, resulting in diminished viability and fermentation capacity. Understanding the mechanisms underlying freeze-thaw stress is essential for mitigating its adverse effects on yeast performance. This review delves into the intricate mechanisms underlying freeze-thaw stress, focusing specifically on Saccharomyces cerevisiae, the primary yeast used in baking, and presents a wide range of biotechnological approaches to enhance freeze-thaw resistance in S. cerevisiae. Strategies include manipulating intracellular metabolites, altering membrane composition, managing antioxidant defenses, mediating aquaporin expression, and employing adaptive evolutionary and breeding techniques. Addressing challenges and strategies associated with freeze-thaw stress, this review provides valuable insights for future research endeavors, aiming to enhance the freeze-thaw tolerance of baker's yeast and contribute to the advancement of bakery science.

The Influence of Various Freezing-thawing Methods of Skin on Drug Permeation and Skin Barrier Function.

The selection of skin is crucial for the in vitro permeation test (IVPT). The purpose of this study was to investigate the influence of different freezing-thawing processes on the barrier function of skin and the transdermal permeability of granisetron and lidocaine. Rat and hairless mouse skins were thawed at three different conditions after being frozen at -20℃ for 9days: thawed at 4℃, room temperature (RT), and 32℃. There were no significant differences in the steady-state fluxes of drugs between fresh and thawed samples, but compared with fresh skin there were significant differences in lag time for the permeation of granisetron in rat skins thawed at RT and 32℃. Histological research and scanning electron microscopy images showed no obvious structural damage on frozen/thawed skin, while immunohistochemical staining and enzyme-linked immunosorbent assay for the tight junction (TJ) protein Cldn-1 showed significantly impaired epidermal barrier. It was concluded that the freezing-thawing process increases the diffusion rate of hydrophilic drugs partly due to the functional degradation of TJs. It's recommended that hairless, inbred strains and identical animal donors should be used, and the selected thawing method of skin should be validated prior to IVPT, especially for hydrophilic drugs.

A framework to model freeze/thaw-induced crack propagation in concrete based on a fatigue phase-field method

Concrete structures in cold regions are exposed to harsh environmental conditions, including freeze–thaw cycles, which lead to frost damage and degradation. Accurate simulation of the freeze–thaw damage process is essential for assessing concrete structures’ performance and service life. This paper presents a novel approach for simulating microcracks propagation in concrete during freeze–thaw cycles based on a fatigue phase-field model, in which a fatigue degradation function is introduced in the energy functional. The commercial software COMSOL is employed to implement the proposed model using a segregated scheme. The proposed model is validated against experimental results presented in the literature. Additionally, three cases are studied to get insight into the freeze–thaw damage. The results demonstrate the effectiveness of the fatigue phase-field model in capturing crack propagation in concrete under freeze–thaw cycles. The developed model offers valuable insights for assessing and designing concrete structures in cold regions.

Freeze-thaw characteristics and deformation monitoring of topsoil in highland pastoral areas under the influence of snow accumulation

Soil freeze–thaw processes and snowmelt infiltration have a significant impact on the hydrological cycle and ecosystem productivity in alpine pastoral areas. To investigate the driving mechanism of snow on soil freeze-thaw processes, a meteorological station was established in the southern part of Namatso Lake, Tibet to collect environmental data. The study included analyzing the relationship between soil temperature and humity, as well as assessing soil freeze-thaw characteristics and the evolution of soil frost heave over time. The freeze-thaw frequency was significantly 43% lower at the surface soil, and the freeze-thaw intensity decreased when the ground was snow-covered. During the initial freezing period, precipitation and soil humidity remain relatively low, and soil moisture decreases linearly with decreasing soil temperature, which occurs in the phenomenon of soil freeze-shrink. During the initial thawing period, snowmelt infiltration impacts soil humidity, and soil frost heave increases logarithmically, reaching a maximum of 5.2 mm, driven by freeze-thaw. Soil moisture decreases under topsoil evaporation in the later stage and again follows a linear trend with the soil temperature. This study not only reveals the correlation between soil temperature and humidity during different freeze-thaw periods but also enhances the understanding of soil deformation patterns under the influence of snow accumulation.

Effect of Compressive Modulus of Porous PVA Hydrogel Coating on the Preventing Adhesion of Polypropylene Mesh.

PP mesh is a widely used prosthetic material in hernia repair. However, visceral adhesion is one of the worst complications of this operation. Hence, an anti-adhesive PP mesh is developed by coating porous polyvinyl alcohol (PVA) hydrogel on PP surface via freezing-thawing process method. The compressive modulus of porous PVA hydrogel coating is first regulated by the addition of porogen sodium bicarbonate (NaHCO3) at various quality ratios with PVA. As expected, the porous hydrogel coating displayed modulus more closely resembling that of native abdominal wall tissue. In vitro tests demonstrate the modified PP mesh show superior coating stability, excellent hemocompatibility, and good cytocompatibility. In vivo experiments illustrate that PP mesh coated by the PVA4 hydrogel that mimicked the modulus of native abdominal wall could prevent adhesion effectively. Based on this, the rapamycin (RPM) is loaded into the porous PVA4 hydrogel coating to further improve anti-adhesive property of PP mesh. The Hematoxylin and eosin (H&E) and Masson trichrome (MT) staining results verified that the resulting mesh could alleviate the inflammation response and reduce the deposition of collagen around the implantation zone. The biomimetic mechanical property and anti-adhesive property of modified PP mesh make it a valuable candidate for application in hernioplasty.

Unraveling microstructural evolution in air-entrained mortar and paste: Insights from MIP and micro-CT tomography amid cyclic freezing-thawing damage

Understanding the microstructure evolution during the cyclic freezing-thawing process is crucial to studying the deterioration mechanisms of concrete under cyclic freezing-thawing. In this study, air voids were entrained into cement mortar and paste by AEA and polymeric microspheres. Mercury intrusion porosimetry (MIP) and micro-CT techniques were integrated to investigate the microstructure of the specimens with various freezing-thawing cycles. After subjecting the Ref. and AEA mixed mortar to 100 and 200 freezing-thaw cycles, an increase in porosity and pore entrapment was observed from the MIP results, suggesting the occurrence of damage induced by cyclic freezing-thawing. Conversely, in the microspheres mixed mortar, the presence of surface adsorbed moisture led to an initial increase in porosity and pore entrapment after 100 freezing-thaw cycles, followed by a decrease after 200 cycles, indicating a healing effect. Micro-CT analysis revealed that while the AEA mixed specimens exhibited higher air content than the microspheres mixed specimens, the latter showed a greater number of voids, which ultimately enhanced their resistance to freezing-thawing. The micro-CT results unveiled that air bubbles tended to merge in AEA mixed specimens, adversely affecting their resistance to freezing-thawing. Conversely, the microsphere-incorporated specimens displayed smooth void distribution curves, indicating a well-distributed air void system that enhances their freezing-thawing resistance. This work suggests that microspheres can be a great candidate for air-entraining materials. Combining the MIP and micro-CT analysis can better understand the microstructure change of concrete with cyclic freezing-thawing.

Characteristics of water and heat change during the freezing-thawing process at an alpine steppe in seasonally frozen ground of the Northern Tibetan plateau

Characteristics of water and heat change during the freezing-thawing process at an alpine steppe in seasonally frozen ground of the Northern Tibetan plateau

Superhydrophobic surface with good anti-icing properties and high durability

Ice formation is a widespread phenomenon in nature, and superhydrophobic surfaces, due to their excellent hydrophobic properties, are extensively employed in the field of ice prevention. In this study, silane coupling agent (Si69) is used to modify the petal-like SiO2 surface to reduce its surface energy. An epoxy/benzoxazine/Si69-SiO2 ternary mixed superhydrophobic surface is constructed on basalt fiber fabric using a spray and thermal curing method. Examination of the data reveals that a 1:2 proportion of Si69-SiO2 and epoxy/benzoxazine yields a surface whose hydrophobicity is quantified by a water contact angle measuring 165±2°. The water droplet bounces three times on the surface, demonstrating optimal superhydrophobicity. Compared to samples without the addition of Si69-SiO2, the icing time is extended by approximately 4.83 times. Following 30 iterations of freeze-thaw processes, the surface retains its exceptional water-repellent properties, demonstrating excellent ice-phobic stability. Furthermore, the surface maintains its superhydrophobic performance, demonstrating excellent mechanical durability, even after being subjected to friction with SiC sandpaper (220 mesh) for 200 cm under a pressure of 3.2 Kpa and reciprocal friction for 30 minutes under a 50 g load. The surface can withstand over 12 hours of acid and alkali corrosion, and it also possesses excellent self-cleaning capabilities.

Numerical investigation of artificial ground freezing–thawing processes in tunnel construction

Artificial ground freezing is a frequently used method for temporary support of the soil in geotechnical interventions, such as tunneling. Besides the time required to form a supporting frozen soil structure during freezing, the prediction of temperature evolution during the thawing process and the final thawing time are also relevant, since settlements induced by thawing of the frozen soil can pose a risk to sensitive structures in urban tunneling. The freezing and thawing process of soils depends strongly on the unfrozen liquid content. The unfrozen liquid content during the freezing and thawing cycles is known to have a pronounced hysteresis response, whose effect on the temperature distribution and groundwater flow, especially at the structural level has not been extensively studied. In this work, we present a thermo-hydraulic finite element model for freezing soils and incorporate the hysteresis behavior of soil. We aim to investigate the suitability of the presented numerical model for tunnel construction on the one hand, and quantify the extent of the influence of the hysteresis response of the unfrozen liquid content at the structural level on the other. To this end, the model is first validated with the help of experimental data from a soil test subjected to a freezing–thawing cycle and subsequently used to analyze three problems of artificial ground freezing in tunnel construction during the freezing phase or freezing–thawing phases. The results show a good agreement with the experimental measurements. We show that the computational model is capable of providing accurate prognosis of the temperature profile as well as broader metrics such as the thickness and shape of the frozen body for tunneling applications under hydrostatic and seepage flow conditions. The hysteresis response is shown to have a significant influence on the coupled thermo-hydraulic process, with thawing times differing depending on whether hysteresis is considered. It is concluded, that the inclusion of the hysteresis response is crucial for obtaining an accurate representation of the freezing process.

Effect of interleukin 6 (IL-6) on sperm quality, kinematic parameters, acrosome integrity, apoptosis, ultrastructure, and molecular docking in cryopreserved ram spermatozoa

Sperm cryopreservation can lead to subfertility due to potential damage to sperm DNA, membranes, and overall motility caused by the freeze-thaw process. Interleukin-6 (IL-6) is a versatile cytokine with various roles in reproductive processes. However, the impacts of IL-6 supplementation on cryopreserved ram sperm have not been thoroughly investigated. Therefore, this study aims to assess the influence of IL-6 on the sperm quality of cryopreserved ram sperm. Ram semen was collected, pooled, and extended with tris-citrate soybean lecithin extender supplemented with 0, 50, 100, and 200 ng/mL of IL-6. The samples experienced a standard freezing protocol, and sperm quality, kinematic parameters, ultrastructure, and molecular docking of cryopreserved ram spermatozoa were evaluated. The results showed that sperm kinematics, viability, progressive motility, and membrane integrity were significantly enhanced by the addition of 100 or 200 ng of IL-6/mL (p < 0.05). Semen supplemented with 100 or 200 ng/mL of IL-6 also exhibited higher percentages of sperm kinematics, including DAP, DCL, DSL, VSL, VAP, VCL, and ALH, compared to other groups (p < 0.05). IL-6 supplementation enhanced acrosome integrity, and reduced caspase-3 activity in post-thawed ram spermatozoa (p < 0.05) compared to untreated group. Supplementation with IL-6 (200 ng/mL) significantly decreased oxidative biomarkers (NO, MDA, and H2O2) (p < 0.001) and improved total antioxidant capacity (p < 0.05). The percentage of sperm damage (tail, head, and midpiece) was significantly reduced by IL-6 supplementation (p < 0.05). Electron micrographs showed that supplementation with 100 or 200 ng/mL IL-6 protected acrosome stability, plasma membrane integrity, and sustained the ultrastructure integrity of cryopreserved ram spermatozoa. The docking exploration indicates a higher binding affinity with sperm function biomarkers, including caspase 3, BCL2, and PSMA6, with binding energies of − 52.30 kcal/mol, − 56.04 kcal/mol, and − 57.06 kcal/mol, respectively. In conclusion, the addition of IL-6 to the freezing extender can enhance the post-thaw quality of cryopreserved ram spermatozoa.

Mechanical strength change and coal damage analysis of frozen saturated bitumite after cryogenic freezing

The changes in mechanical strength and damage analysis of bitumite under the action of liquid nitrogen (LN2) freezing are critical issues that need to be addressed in the application of LN2 in coal seam permeability enhancement. Using an MTS testing machine, strain gauges, and ultrasonic detection instruments, experiments were conducted to obtain stress-strain curves and ultrasonic time-domain images of coal samples after single freezing and cyclic freeze-thaw processes. These data were analyzed to understand the mechanical performance and internal fracture evolution of coal samples subjected to ultra-low temperatures of LN2. The experimental results indicate that: (1) the uniaxial compressive strength and elastic modulus of coal samples subjected to a single LN2 freeze are positively correlated with the freezing time from 0 to 50 min, and negatively correlated with the freezing time from 50 to 180 min. (2) The uniaxial compressive strength and elastic modulus of coal samples subjected to cyclic freezing and thawing with LN2 decrease as the number of freeze-thaw cycles increases. (3) The Poisson's ratio of coal samples subjected to single freezing and cyclic freezing-thawing is negatively correlated with the absolute freezing time. Additionally, the decrease in Poisson's ratio is greater in coal samples subjected to cyclic freezing-thawing compared to those subjected to single freezing. (4) As the absolute freezing time increases, the ultrasonic waveforms of the coal samples begin to become disordered, which is manifested by a decrease in amplitude and a delay in the arrival time of the first wave. Under ultra-low temperature conditions, LN2 can deteriorate the mechanical properties of coal samples, with the degree of deterioration being greater under cyclic freezing-thawing than single freezing. This study can provide theoretical guidance for increasing the permeability of coal seams.

Effects of hydroxytyrosol on post-thaw quality of rooster sperm.

Semen cryopreservation is one of the most important reproduction techniques in the livestock and poultry industry. Cryopreservation induces cold stress, generating reactive oxygen species (ROS) and oxidative stress causing structural and biochemical damages in sperm. In this study, we evaluated the effects of the hydroxytyrosol (HT), as an antioxidant, at the concentrations of 0, 25, 50, and 100 μg/mL on post-thaw semen quality metrics in rooster. Semen samples were collected twice a week from 10 roosters (29 weeks), processed and frozen according to experimental groups. Different quality parameters, including total motility, progressive motility, viability, morphology, membrane integrity, and malondialdehyde were measured after thawing. Results showed that 25 and 50 μg/mL of HT produced the highest percentage of total motility (51.01 ± 2.19 and 50.15 ± 2.19, respectively) and progressive motility (35.74 ± 1.34 and 35.15 ± 1.34, respectively), membrane integrity (48.00 ± 2.18 and 46.75 ± 2.18, respectively) as well as viability (53.00 ± 2.17 and 52.50 ± 2.17, respectively) compared with the other groups (p < .05). The group with 25 μg/mL of HT showed the lowest significant (p < .05) MDA concentration (1.81 ± 0.25). Our results showed that the effect of HT was not dose-dependent and optimum concentration of HT could improve functional parameters of rooster sperm after freezing-thawing. These findings suggest that HT may have protective effects on the rooster sperm during the freezing-thawing process.

LC-MS/MS analysis of didehydrostemofoline from Stemona collinsiae roots extracts in rats plasma and pharmacokinetics profile after oral administration

Stemona collinsiae Craib., Stemonaceae, has been traditionally used as medicinal plants for insecticides, treatment of parasitic worms and various diseases in Southeast Asian countries. Its ethanolic root extract has been postulated for anthelminthic activities which has a potential for development for human gnathostomiasis drug. To investigate the pharmacokinetic profile, liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method for the quantification of didehydrostemofoline in rats' plasma was developed and validated. The chromatographic separation was performed on a C18 column using 1 mM ammonium acetate in water and methanol (50:50, v/v). Tetrahydropalmatine was used as an internal standard. The multiple reaction monitoring mode was used for quantitative analysis. The validated method showed good sensitivity, linearity, precision, and accuracy. The results of stability showed that didehydrostemofoline was stable in the extracted samples in auto-sampler for 24 h and in the plasma samples under room temperature for 24 h, −20 °C for 1 month, and after three freeze-thaw processes. The developed method was applied to the pharmacokinetic study of didehydrostemofoline after oral administration of S. collinsiae root extract. Didehydrostemofoline was rapidly absorbed from the gastrointestinal tract. The time to peak drug concentration was 1.75 ± 0.62 h with maximum drug concentration of 1152.58 ± 271.18 ng/mL. Didehydrostemofoline was rapidly eliminated from the body with terminal half-life of 1.86 ± 0.50 h. Calculated drug clearance of didehydrostemofoline was 96.82 ± 23.51 L/h and volume of distribution was 260.40 ± 96.81 L. The present study provided useful data for understanding drug disposition in the body with dynamic time-course which could be beneficial for further clinical trials.

Peridynamic simulation of micro-internal damage and macro-mechanical properties of cement paste under freeze-thaw cycles

Concrete is a multi-phase, multi-component, heterogeneous composite material and a typical porous medium with a complex microstructure. Under freeze-thaw cycles (FTCs), pressures from the freezing and migration of water within the pores of the concrete cause freeze-thaw damage, which is influenced by its microstructure. To effectively simulate and understand the freeze-thaw damage mechanism, it is crucial to use a geometric structure that reflects the actual pore distribution. This study employs the μic model to create a geometric structure of hardened cement paste, capturing the spatial distribution of pores. The study utilizes the peridynamics (PD) method based on ice formation and crystallization thermodynamics to investigate the freeze-thaw damage evolution and the deterioration of mechanical properties in cement paste under FTCs. The simulations revealed the entire freeze-thaw damage process of cement paste, including internal crack initiation and propagation, as well as surface freeze-thaw spalling. The freeze-thaw damage of cement paste intensifies with increasing FTCs, and the extension of cracks diminishes the interconnection among the skeletons constituting the cement paste microstructure, leading to decreased tensile strength and elastic modulus. Additionally, the stress-strain evolution behavior of freeze-thaw cement paste under uniaxial tensile loads was obtained. The tensile strength and elastic modulus of cement paste decrease with increasing FTCs, and the higher the water-cement (w/c) ratio, the greater the reduction in strength and modulus.

Study on salt-frost heave characteristics, improvement effect, and curing mechanism of loess-like sulphate soil

Aiming at the obvious salt-frost heave disease of loess-like sulphate soil in seasonal frozen areas, the compaction characteristics, salt-frost heave property and improvement effect of saline soil treated by adding lime, silica fume and lime-silica fume mixture are investigated. The results show that the salt-frost heave and collapse occur alternately and periodically with the freeze-thaw process. In addition, the peak salt-frost heave and thawing residual salt-frost heave increases with the increasing salt content, and the salt-frost heave shows obvious linear accumulation. The composition and dosage of the curing agent, freeze-thaw times and maintenance time have a significant influence on the improvement effect of salt-frost heave. The improvement effect of the lime-silica fume mixture far exceeds that of lime or silica fume alone. Moreover, repeated freeze-thaw cycles have a significant deteriorating effect on reducing salt-frost heave, and the salt-frost heave decreases with increasing maintenance time. The mechanism of curing saline soil by lime-silica fume mixture mainly includes physical filling effect and pozzolanic reaction effect. In particular, the strong pozzolanic reaction between lime and silica fume produces cementing material (CSH), effectively cementing the soil particles and substantially inhibiting the salt-frost heave.

The Effect of Freeze-thaw on Mechanical and Ultrasonic Properties of Hungarian Oolitic Stones

The freeze-thaw process is a weathering phenomenon that occurs in rocks and stones when water enters small cracks and pores within the stone. When the temperature drops below freezing, the water inside the rock expands as it freezes, exerting pressure on the rock from within. In this study the effect of freeze thaw on mechanical parameter uniaxial compression strength (UCS) and ultrasonic pulse velocity (UPV) of 47 oolitic samples were considered. At first, capillary absorption for cylindrical and prismatic oolitic samples were measured and then freeze-thaw experiment with 23 cycles were applied to the samples. UPV of samples before and after freeze-thaw was analysed by two ultrasonic devices including Geotron and Pundit. It was observed that freeze thaw decreases primary velocity (Vp) and secondary velocity (Vs) by around 20 and 7% respectively. However, average UCS of 1.6 MPa indicates strength decrease of samples, which represent negative effect of pore expansion due to freeze thaw on strength parameter of samples.

Assessment of hydraulic and thermal properties of the Antarctic active layer: Insights from laboratory column experiments and inverse modeling

To better understand the changes in the hydrologic cycle caused by global warming in Antarctica, it is crucial to improve our understanding of the groundwater flow system, which has received less attention despite its significance. Both hydraulic and thermal properties of the active layer, through which groundwater can flow during thawing seasons, are essential to quantify the groundwater flow system. However, there has been insufficient information on the Antarctic active layer. The goal of this study was to estimate the hydraulic and thermal properties of Antarctic soils through laboratory column experiments and inverse modeling. The column experiments were conducted with sediments collected from two lakes in the Barton Peninsula, Antarctica. A sand column was also operated for comparison. Inverse modeling using HydroGeoSphere (HGS) combined with Parameter ESTimation (PEST) was performed with data collected from the column experiments, including permeameter tests, saturation-drain tests, and freeze-thaw tests. Hydraulic parameters (i.e., Ks, θs, Swr, α, β, and Ss) and thermal diffusivity (D) of the soils were derived from water retention curves and temperature curves with depth, respectively. The hydraulic properties of the Antarctic soil samples, estimated through inverse modeling, were 1.6 × 10−5–3.4 × 10−4 cm s−1 for Ks, 0.37–0.42 for θs, 6.62 × 10−3–1.05 × 10−2 for Swr, 0.53–0.58 cm−1 for α, 5.75–7.96 for β, and 5.11 × 10−5–9.02 × 10−5 cm−1 for Ss. The thermal diffusivities for the soils were estimated to be 0.65–4.64 cm2 min−1. The soil hydraulic and thermal properties reflected the physical and ecological characteristics of their lake environments. The results of this study can provide a basis for groundwater-surface water interaction in polar regions, which is governed by variably-saturated flow and freeze-thaw processes.

Advancements in Understanding and Enhancing Antioxidant-Mediated Sperm Cryopreservation in Small Ruminants: Challenges and Perspectives.

Cryopreservation poses significant challenges to the preservation of sperm integrity and function, particularly in small ruminants where cryodamage is pronounced. This review explores the molecular mechanisms underlying sperm cryodamage and strategies for improving cryopreservation outcomes, with a focus on the role of antioxidants. Cryopreservation-induced alterations in proteins and RNA transcripts critical for sperm function, including motility, capacitation, fertilization, and embryo development, are discussed. Proteomic, transcriptomic, and epigenomic advancements have provided valuable insights into these mechanisms, offering potential biomarkers for predicting sperm freezability and enhancing cryopreservation strategies. Combining technologies such as mass spectrometry and flow cytometry allows for a comprehensive understanding of molecular and cellular changes induced by the freezing-thawing process. However, challenges remain in optimizing cryoprotectant formulations and antioxidant supplementation to improve post-thaw sperm fertility. Further research is needed to explore a wider range of novel cryoprotectants, antioxidants, and proteins for cryopreservation media, as well as to validate their efficacy in enhancing sperm viability and function. Additionally, investigations into the effects of cryopreservation on RNA transcripts and epigenetic factors in small ruminant species are warranted to advance our understanding of sperm preservation. Overall, this review highlights the importance of antioxidants in mitigating cryodamage and underscores the need for continued research to refine cryopreservation protocols and improve reproductive outcomes in small ruminants.