Thawing Stage Research Articles

Investigation on moisture-heat-deformation behaviors of the ordinary railway subgrade in seasonally frozen regions

The stability and service performance of ordinary railway subgrade are often challenged by frost heave distresses in seasonally frozen regions. This paper analysis the moisture-heat process and frost heave characteristics of the subgrade of Qinghai-Tibet Railway (QTR) using on-site monitoring data. The development mechanism of deep frost heave in ordinary railway is discussed, and combined with numerical simulation, the mechanism of significant lateral differential frost heave of ordinary railway subgrade is also revealed. The monitoring results show that the maximum freezing depth of the subgrade is 1.88 m, and the maximum frost heave is 32 mm. The freezing cycle can be divided into four stages by freezing rate and thawing rate: repeated freezing-thawing cycles, rapid freezing stage, slow freezing stage, and bidirectional thawing stage. The freezing rate of 0.53 cm/d and high moisture content of subgrade in the slow freezing stage are the main reasons for the development of deep frost heave in ordinary railway subgrade. The existence of ballast layer is the primary factor that causes the difference of initial freezing time, moisture-heat change and distribution at different positions of ordinary railway subgrade, which ultimately results in the lateral differential frost heave exceeding the allowable value of 15 mm.

Ultrasonic technology for predicting beef thawing degree and endpoint

Precise control and accurate endpoint determination in the thawing of frozen beef are vital for maintaining its quality and safety in the food industry. Traditional thawing methods, which are time-controlled, often lead to inconsistencies like under or over-thawing, adversely affecting texture, color, nutritional value, and increasing the risk of microbial contamination. This study introduces a novel, non-destructive approach using ultrasonic signals and ultrasonic velocity for the quantification of beef thawing. It involves analyzing thermal images of beef cross-sections to assess thawing levels and gathering ultrasonic data at various thawing stages. Machine learning algorithms, including KNN, ANN, Extra-Trees, and LightGBM, were employed to develop prediction models that accurately identify the thawing endpoint. The models exhibit high accuracy, with R^2 values exceeding 0.9, some reaching as high as 0.986. This method represents a significant advancement in non-destructive quality control, enhancing safety and quality management in the beef processing sector.

Virus ecology and 7-year temporal dynamics across a permafrost thaw gradient.

Soil microorganisms are pivotal in the global carbon cycle, but the viruses that affect them and their impact on ecosystems are less understood. In this study, we explored the diversity, dynamics, and ecology of soil viruses through 379 metagenomes collected annually from 2010 to 2017. These samples spanned the seasonally thawed active layer of a permafrost thaw gradient, which included palsa, bog, and fen habitats. We identified 5051 virus operational taxonomic units (vOTUs), doubling the known viruses for this site. These vOTUs were largely ephemeral within habitats, suggesting a turnover at the vOTU level from year to year. While the diversity varied by thaw stage and depth-related patterns were specific to each habitat, the virus communities did not significantly change over time. The abundance ratios of virus to host at the phylum level did not show consistent trends across the thaw gradient, depth, or time. To assess potential ecosystem impacts, we predicted hosts in silico and found viruses linked to microbial lineages involved in the carbon cycle, such as methanotrophy and methanogenesis. This included the identification of viruses of Candidatus Methanoflorens, a significant global methane contributor. We also detected a variety of potential auxiliary metabolic genes, including 24 carbon-degrading glycoside hydrolases, six of which are uniquely terrestrial. In conclusion, these long-term observations enhance our understanding of soil viruses in the context of climate-relevant processes and provide opportunities to explore their role in terrestrial carbon cycling.

Interactions between iron and carbon in permafrost thaw ponds

Thawing permafrost forms “thaw ponds” that accumulate and transport organic carbon (OC), redox-active iron (Fe), and other elements. Although Fe has been shown to act as a control on the microbial degradation of OC in permafrost soils, the role of iron in carbon cycling in thaw ponds remains poorly understood. Here, we investigated Fe-OC interactions in thaw ponds in partially and fully thawed soils (“bog” and “fen” thaw ponds, respectively) in a permafrost peatland complex in Abisko, Sweden, using size separation (large particulate fraction (LPF), small particulate fraction (SPF), and dissolved fraction (DF)), acid extractions, scanning electron microscopy (SEM), Fe K-edge X-ray absorption spectroscopy (XAS), and Fourier Transform Infrared (FTIR) spectroscopy. The bulk total Fe (total suspended Fe) in the bogs ranged from 135 mg/L (mean = 13 mg/L) whereas the fens exhibited higher total Fe (1.5 to 212 mg/L, mean = 30 mg/L). The concentration of bulk total OC (TOC) in the bog thaw ponds ranged from 50 to 352 mg/L (mean = 170 mg/L), higher than the TOC concentration in the fen thaw ponds (8.5 to 268 mg/L, mean = 17 mg/L). The concentration of 1 M HCl-extractable Fe in the bog ponds was slightly lower than that in the fens (93 ± 1.2 and 137 ± 3.5 mg/L Fe, respectively) with Fe predominantly (>75 %) in the DF in both thaw stages. Fe K-edge XAS analysis showed that while Fe(II) was the predominant species in LPF, Fe(III) was more abundant in the DF, indicating that the stage of thawing and particle size may control Fe redox state. Furthermore, Fe(II) and Fe(III) were partially complexed with natural organic matter (NOM, 8 to 80 %) in both thaw ponds. Results of our work suggest that Fe and OC released during permafrost thaw into thaw ponds (re-)associate, potentially protecting OC from microbial decomposition while also stabilizing the redox state of Fe.

Oilfield Brine as a Source of Water and Valuable Raw Materials—Proof of Concept on a Laboratory Scale

Oilfield brine is the largest byproduct stream generated during the extraction of crude oil and natural gas and may be considered a resource for the production of potable water and valuable raw materials. The high salinity of such waters limits the application of typical membrane-based techniques. In most oilfields, waste cold energy from the process of the low-temperature separation of natural gas is available and may be used as a source of cold for the freezing desalination (FD) of brine. As a result of the FD process, two streams are obtained: partially desalinated water and concentrated brine. The partially desalinated water may be suitable for non-potable applications or as a feed for membrane desalination. The concentrated brine from the FD could be used as a feed for the recovery of selected chemicals. This paper focuses on verifying the above-described concept of the freezing desalination of oilfield brine on a laboratory scale. The brine from a Polish oilfield located in the Carpathian Foredeep was used as a feed. Four freezing–thawing stages were applied to obtain low-salinity water, which subsequently was treated by reverse osmosis. The obtained permeate meets the criteria recommended for irrigation and livestock watering. The concentrated brine enriched with iodine (48 mg/L) and lithium (14 mg/L) was subjected to recovery tests. Ion exchange resin Diaion NSA100 allowed us to recover 58% of iodine. Lithium recovery using Mn- and Ti-based sorbents varies from 52 to 93%.

Coupled surface-internal deformation monitoring in three-dimensional space for freezing-thawing soil

Soil frost deformation significantly influences engineering projects in cold regions. The anisotropic behavior of soil, involving surface and internal deformation in three dimensions (3D), introduces inaccuracies in evaluating freeze–thaw geological hazards. To explore the relationship between internal strain and surface displacement of soil in a 3D space during the freezing-thawing process, a platform for monitoring coupled surface-internal deformation in 3D were developed using binocular recognition technology and a novel 3D strain rosette. Subsequently, a freezing-thawing model test of soil in Dalian Offshore Airport filling is conducted using the platform. The results show that, the internal strain of soil is closely associated with the boundary conditions of the test unit. During freezing test, the vertical strain exhibits a more significant increase in comparison to the horizontal strain. Surface displacements in soil primarily occur during the initial freezing and thawing stages. The variation of surface horizontal displacement in each direction is minimal throughout the freezing-thawing process. A surface freezing boundary leads to an increment in internal strain, while the deep frozen stress relief causes the soil surface expand during thawing. This study provides a suggestion for the control of the cold source in cold region engineering.

Frozen shoulder release: Ten-step technique

Frozen shoulder is a condition associated with painful restriction of shoulder joint movement. This condition has a prevalence of 2–5% in the general population, seen most often in females and the diabetic population. It is essentially a self-limiting condition passing through stages of freezing, frozen, and thawing. It has been reported that up to 90% of patients recover with conservative measures. Patients with more severe initial symptoms, younger age at the time of onset, and reduction in motion despite four months of compliance with therapy are most likely to require surgery. The author presents ten-step techniques for frozen shoulder release in cases of failed conservative trials in the management of frozen shoulder.

Emerging investigator series: preferential adsorption and coprecipitation of permafrost organic matter with poorly crystalline iron minerals.

Future permafrost thaw will likely lead to substantial release of greenhouse gases due to thawing of previously unavailable organic carbon (OC). Accurate predictions of this release are limited by poor knowledge of the bioavailability of mobilized OC during thaw. Organic carbon bioavailability decreases due to adsorption to, or coprecipitation with, poorly crystalline ferric iron (Fe(III)) (oxyhydr)oxide minerals but the maximum binding extent and binding selectivity of permafrost OC to these minerals is unknown. We therefore utilized water-extractable organic matter (WEOM) from soils across a permafrost thaw gradient to quantify adsorption and coprecipitation processes with poorly crystalline Fe(III) (oxyhydr)oxides. We found that the maximum adsorption capacity of WEOM from intact and partly thawed permafrost soils was similar (204 and 226 mg C g-1 ferrihydrite, respectively) but decreased to 81 mg C g-1 ferrihydrite for WEOM from the fully thawed site. In comparison, coprecipitation of WEOM from intact and partly thawed soils with Fe immobilized up to 925 and 1532 mg C g-1 Fe respectively due to formation of precipitated Fe(III)-OC phases. Analysis of the OC composition before and after adsorption/coprecipitation revealed that high molecular weight, oxygen-rich, carboxylic- and aromatic-rich OC was preferentially bound to Fe(III) minerals relative to low molecular weight, aliphatic-rich compounds which may be more bioavailable. This selective binding effect was stronger after adsorption than coprecipitation. Our results suggest that OC binding by Fe(III) (oxyhydr)oxides sharply decreases under fully thawed conditions and that small, aliphatic OC molecules that may be readily bioavailable are less protected across all thaw stages.

Effects of Adding Glutathione to AndroMed Diluent on Intact Plasma and Acrosome Membranes, and Progressive Motility of Cattle Spermatozoa During Freezing Processes

Adding endogenous antioxidants to the diluent is significantly associated with semen quality during the freezing process. This study aimed to investigate the effects of adding glutathione to AndroMed diluent on the preservation of crucial sperm attributes, namely, intact plasma membrane (IPM), intact acrosome membrane (IAM), and progressive motility of Bali cattle spermatozoa. A completely randomized design was used, and spermatozoa samples were obtained from a Bali cattle and divided into two diluent treatment groups (36 diluent samples in each group with six replications), namely pure AndroMed as the control and a group with the addition of glutathione (1 mmol) to AndroMed. Each treatment was replicated six times and evaluated at three freezing stages, including post-dilution, post-equilibration, and post-thawing, for crucial sperm properties. The results indicated that fresh Bali cattle spermatozoa had progressive motility, IAM, and IPM of 75%, 89%, and 88%, respectively. During the freezing process, there was a significant decrease in semen quality, including progressive motility, IAM, and IPM of spermatozoa after dilution to post-equilibration and post-equilibration to post-thawing in both treatment groups. Meanwhile, the addition of 1 mmol of glutathione to AndroMed diluent had a significant difference in increasing progressive motility, IAM, and IPM of Bali cattle spermatozoa at each stage of semen freezing, including post-dilution, post-equilibration, and post thawing when compared with controls. Based on the results, it can be concluded that adding 1 mmol of glutathione to the AndroMed diluent enhanced the quality and integrity of Bali cattle semen, including progressive motility, IAM, and IPM during the freezing process.

Subsurface mixing of different soil water pools in a permafrost-underlain headwater catchment, Qilian Mountains, Northeastern Tibetan Plateau

Recently studies postulate that there are two distinct soil water pools, i.e., mobile and immobile soil water (MSW and IMSW), and different soil waters have different mobility to generate runoff. Evaluating the influences of soil thawing on the subsurface mixing between different soil waters is important for understanding subsurface hydrological processes. In this study, the isotopic differences between different soil waters were evaluated in a permafrost-underlain headwater catchment by comparing the variations of stable isotopes and seasonal origin of MSW and bulk soil water (BSW), including both IMSW and MSW. BSW was sampled using soil augering and cryogenic vacuum distillation in thawed and frozen soil layers, and MSW was collected using a zero-tension lysimeter in thawed soil layers. The results show the following: (1) The average δ2H values of MSW, thawed BSW, and frozen BSW were similar during the spring snowmelt period (SSP), this can be attributed to weak evaporation and their similar origin, which is supported by the high line-conditioned excess values and their similar seasonal origin index values. (2) The enriched MSW collected during the SRP compared to the spring MSW and was associated with enriched summer precipitation, and the IMSW experienced strong evaporation during the period from the SSP to the SRP, both leading to enriched summer BSW compared to the spring BSW. (3) The frozen and thawed BSW had very similar isotopic compositions and seasonal origin, indicating the close hydrological connection between them and the important recharge of the melting frozen soil to soil water or runoff. The different freeze–thaw stages and soil moisture conditions controlled the stable isotope variations and mixing of different soil waters, this results in the different mobility of the mobile/immobile soil waters involved in the runoff generation processes during the SRP and the SSP, and therefore these features are useful to verify the isotopes-aided precipitation–runoff models applied in such catchments.

Numerical Study of Coupled Water and Vapor Flow, Heat Transfer, and Solute Transport in Variably‐Saturated Deformable Soil During Freeze‐Thaw Cycles

AbstractAs climate change intensifies, soil water flow, heat transfer, and solute transport in the active, unfrozen zones within permafrost and seasonally frozen ground exhibit progressively more complex interactions that are difficult to elucidate with measurements alone. For example, frozen conditions impede water flow and solute transport in soil, while heat and mass transfer are significantly affected by high thermal inertia generated from water‐ice phase change during the freeze‐thaw cycle. To assist in understanding these subsurface processes, the current study presents a coupled two‐dimensional model, which examines heat conduction‐convection with water‐ice phase change, soil water (liquid water and vapor) and groundwater flow, advective‐dispersive solute transport with sorption, and soil deformation (frost heave and thaw settlement) in variably saturated soils subjected to freeze‐thaw actions. This coupled multiphysics problem is numerically solved using the finite element method. The model's performance is first verified by comparison to a well‐documented freezing test on unsaturated soil in a laboratory environment obtained from the literature. Then based on the proposed model, we quantify the impacts of freeze‐thaw cycles on the distribution of temperature, water content, displacement history, and solute concentration in three distinct soil types, including sand, silt and clay textures. The influence of fluctuations in the air temperature, groundwater level, hydraulic conductivity, and solute transport parameters was also comparatively studied. The results show that (a) there is a significant bidirectional exchange between groundwater in the saturated zone and soil water in the vadose zone during freeze‐thaw periods, and its magnitude increases with the combined influence of higher hydraulic conductivity and higher capillarity; (b) the rapid dewatering ahead of the freezing front causes local volume shrinkage within the non‐frozen region when the freezing front propagates downward during the freezing stage and this volume shrinkage reduces the impact of frost heave due to ice formation. This gradually recovers when the thawed water replenishes the water loss zone during the thawing stage; and (c) the profiles of soil moisture, temperature, displacement, and solute concentration during freeze‐thaw cycles are sensitive to the changes in amplitude and freeze‐thaw period of the sinusoidal varying air temperature near the ground surface, hydraulic conductivity of soil texture, and the initial groundwater levels. Our modeling framework and simulation results highlight the need to account for coupled thermal‐hydraulic‐mechanical‐chemical behaviors to better understand soil water and groundwater dynamics during freeze‐thaw cycles and further help explain the observed changes in water cycles and landscape evolution in cold regions.

Effects of phase change material inclusion on reducing greenhouse gas emissions from soil in cold region.

Increased gas emissions from soil into the atmosphere are one form of ecosystem feedback in response to climate change. Soil temperature plays a critical role in the soil emission of carbon dioxide (CO2) and nitrous oxide (N2O) suggesting that the release of gases can be reduced by regulating soil temperature. This study proposes a green microencapsulated phase-change material (mPCM) as a soil temperature regulator due to its ability to absorb and release heat during temperature phase transition. The objective is to test how mPCM in soil mixtures influences CO2 and N2O fluxes under laboratory-controlled conditions. For this purpose, a series of soil incubations were carried out with different temperature regimes and soil moisture. The test results revealed that at 20% soil moisture mPCM reduced cumulative CO2 emissions from the soil by 16.4% during the thawing stage and by 20.5% during the freezing stage. At 25% soil moisture, mPCM showed a greater effect reducing cumulative CO2 emissions by 23.9% during the thawing stage and by 24.2% during the freezing stage. At below-zero temperatures, mPCM reduced the total N2O flux by 11.6% at 20% soil moisture and by 26.0% at 25% soil moisture, compared to soil without mPCM. As soil moisture increased, the effects of mPCM on CO2 and N2O fluxes became more pronounced. Cyclic freezing and thawing of soil led to an increase in gas flux. This variation was reduced by the mPCM due to its ability to mitigate the change of soil temperature. Inhibition of the rise in soil temperature due to the inclusion of mPCM reduced the rate of activation of soil mineralization, which reduced gas fluxes. This study demonstrates the potential of mPCM application to reduce greenhouse gas emissions from soil through thermoregulation.

Stochastic representation of spatial variability in thaw depth in permafrost boreal forests

AbstractA simple stochastic representation of the spatial variability in thaw depth is proposed. Thaw depth distribution measured in the two larch‐type forests in eastern Siberia, Spasskaya Pad and Elgeeii, showed different spatial, seasonal, and interannual variability, respectively. Year‐to‐year variation in active‐layer thickness was minor in Spasskaya Pad compared to Elgeeii. A gamma distribution adequately represented both sites' thaw depth spatial variability as the cumulative probability. Thus, we developed a simple model using the gamma distribution that illustrates the spatial variability in thaw depth at any thawing stage as a function of a given mean thaw depth. A hierarchy of models was introduced that sequentially considered the constant state, linearity, and nonlinearity in the dependence of the rate parameter of the gamma distribution on the mean thaw depth. Although the requirements of the model levels differed between Spasskaya Pad and Elgeeii, the proposed model successfully represented the spatial variability in thaw depth at both sites during different thaw seasons.

Effect of the interlayer on soil temperature and the transformation between phreatic water and soil water under laboratory freeze-thaw action

To reveal the effect of interlayer on the temperature of freeze-thaw soil and the transformation between phreatic water and soil water in shallow groundwater areas, a freeze-thaw test was conducted with a groundwater table depth of 0.5 m under laboratory freeze-thaw action. The soil temperature and the transformation between phreatic water and soil water of sand columns under constant freezing temperature at −20°C lasted for 20 days, and the thawing process lasted for 15 days were monitored. The interlayers with a particle size of 0.1–0.5 mm (d50 = 0.3 mm) and a thickness of 5 cm were set at 5, 15, 20, and 25 cm away from the surface and these sand columns were marked as D5, D15, D20, and D25, which were compared with a homogeneous sand column (Ch) with a particle size of 0.5–1.5 mm (d50 = 1.0 mm). The results showed that the fine particle interlayer had thermal insulation on the soil profile and that it effectively inhibited upward migration of phreatic water to soil water during the freezing process. A sand column that had a near-surface interlayer had a better thermal insulation, a stronger inhibition effect on upward migration amount of phreatic water to soil water (UMA) and a larger cumulative downward movement amount of soil water to phreatic water (DMA). The cumulative UMA of D5, D15, D20, and D25 was 61%–84% of Ch during the freezing stage, and the cumulative DMA of D5, D15, D20, and D25 was 29%–57% of Ch during the thawing stage. The inefficient loss of groundwater increased exponentially with the depth of interlayer, the sand column with an interlayer that was farther away from the surface consumed more groundwater and stored more water in the unsaturated zone, and its DMA reached almost zero earlier. These research results were significant for the scientific evaluation of water resources in shallow groundwater areas.

Characteristics of the soil macropore and root architecture of alpine meadows during the seasonal freezing-thawing process and their impact on water transport in the Qinghai Lake watershed, northeastern Qinghai–Tibet Plateau

Low temperatures, freezing-thawing cycles, and short growing seasons characterize alpine soils. The mattic epipedon, a special diagnostic surface horizon with an intensive root network, is widely distributed in alpine ecosystems. Studies on the soil macropores and roots of the mattic epipedon layer in response to seasonal freezing-thawing processes on the Qinghai–Tibet Plateau are lacking. This study characterized the soil macropores and roots of alpine meadows during the seasonal freezing-thawing process using X-ray computed tomography and revealed the influence of soil macropores and roots structure on water transport in the mattic epipedon layer of the alpine meadows. The results showed that the soil pore distribution was more uniform during the unstable freezing stage (UFP) and the unstable thawing stage (UTP), whereas there was a clear mattic epipedon layer during the completely thawed stage (TP) and the completely frozen stage (FP). Soils in the TP stage had a higher total surface area density (0.1898 mm² mm⁻³), length density (225.28 mm mm⁻³), node density (1,592 no. mm⁻³), and connectivity (0.3144) of soil macropores than those in the UFP, UTP, and FP stages. In the TP stages, the density, surface area density, branch density, length density, and node density of roots had significant correlations with the macroporosity, surface area density, length density, node density, and tortuosity of soil macropores. In the FP stage, there were no correlations between the root and soil macropore characteristics. Vertical water is expected to move more readily through the mattic epipedon in the TP stage than in the UFP and UTP stages. Roots were the preferential pathways for water transport into the soil layer of the alpine meadow. Therefore, the mattic epipedon is a key layer for water and nutrient storage and plays an important role in the water-holding function of the Tibetan Plateau due to its greater root development.

Supporting Mechanism of Pile-Anchor Systems for Deep Foundation Pits in Alpine Regions during the Spring Thaw

This study investigated the supporting mechanism of the retaining piles and prestressed anchor cables of a deep foundation pit in alpine regions during the spring thaw. A numerical model was developed based on a subway project in Changchun City. Field monitoring data and the numerical model were used to analyze the variations in the ground settlement, horizontal displacement of the pile tops, and axial force of the anchor cables during the spring thaw under different working conditions. The results demonstrated that changes in the ground settlement primarily occurred in the late stages of the spring thaw with no obvious settlement phenomena because of the thaw. The pile top displacement of most piles remained stable. The axial force of the anchor cables gradually decreased and then sharply increased early in the spring thaw and then slowly decreased in the middle and late stages. Increasing the pile length decreased the pile top displacement to a certain point. Moreover, increasing the pile length increased the axial force of the first anchor cable but decreased the axial force of the lower four anchor cables. Furthermore, increasing the pile spacing increased the pile top displacement and axial force of the five anchor cables. Increasing the incident angle of the anchor cables decreased the pile top displacement and increased the axial force of the first, third, and fourth cables. The axial force of the second cable was minimized at an incident angle of 14°, and the axial force of the fifth cable was minimized at incident angles of 16° and 18°.

Effect of magnetic field on quality improvement of medium‐term delivery frozen pepper

AbstractThe water loss of medium‐term delivery frozen pepper is significant, resulting in the decline of product quality and the loss of nutrients. Hydrocolloids have been proved to help reduce the water loss of fruits and vegetables. Applying magnetic field can reduce the size of ice crystals during freezing, thus preventing cell damage and reducing water loss. In this study, the pickled red pepper was first soaked in gellan gum solution, and then frozen by magnetic field assisted freezing method to reduce the water loss of pepper products during storage. The process was accelerated by repeated (2–6 times) freezing and thawing, so as to reach the standard of medium‐term delivery faster. At the same time, the thawing stage was also supplemented by the action of magnetic field to explore its thawing effect. The results showed that freezing at 10 mT and −20°C and thawing at 4°C and 10 mT can better maintain the texture characteristics of pepper products compared to the control group, thereby reducing the water loss from 40% to 5%, increasing the color appeal, and reducing the loss of red pigment.Practical applicationsThis study provides a simple and novel method to reduce the water loss of frozen products during thawing. These steps combine hydrophilic colloid and magnetic field exploration to reduce the water loss of frozen products, and provide new ideas for product freezing and thawing.

Exploratory study on tissue ablation with cryoelectrolysis.

This is an exploratory study on the effect of electrolysis, delivered during the thawing stage of a cryoablation protocol, on tissue ablation. This treatment protocol, that combines freezing and electrolysis, is named "cryoelectrolysis". In cryoelectrolysis the cryoablation probe is also used as the electrolysis delivering electrode. The study was performed on the liver of Landrace pigs and the tissues were examined 24 hours after treatment (two pigs) and 48 hours after treatment (one pig). The cryoelectrolysis device and different cryoelectrolysis ablation configurations tested are described. This exploratory, non-statistical study shows that the addition of electrolysis expands the ablated area in comparison to cryoablation alone and that there is a substantial difference between the histological appearance of tissue treated by cryoablation alone, tissue treated by cryoablation and electrolysis at the anode and tissue treated by cryoablation and electrolysis at the cathode.

Freezability and Fertility Rates of Stallion Semen Supplemented With Trehalose in Lactose Extender

Cryopreservation of stallion semen is often associated with poor post-thaw sperm quality. One of the reason for this diminished quality is osmotic stress that spermatozoa experiences during freezing and thawing process. The aim of the present study was to evaluate the cryoprotective effect of trehalose on stallion sperm quality and field fertility rates subjected to cooling and freeze–thawing process. Semen samples were collected from six Marwari breed stallions, divided into three different treatments in a final concentration of 150 × 106 sperm/mL by using Lactose based extender containing 0, 50, and 150 mM of trehalose then subjected to cryopreservation after equilibration. Sperm motility, acrosome integrity, plasma membrane integrity, mitochondrial membrane potential, DNA integrity and oxidative stress related parameters of the stallion spermatozoa were analyzed at fresh, prefreeze and post thaw stages. Thirty (30) reproductively healthy mares were inseminated with frozen-thawed semen either supplemented with (treatment) or without (control) trehalose to evaluate the field fertility. Results of the current study indicated that, the extender containing 50 mM trehalose has enhanced the functional plasma membrane, acrosomal, DNA integrities and augmented the mitochondrial membrane potential. Trehalose supplementation to the semen extender not only ameliorated the semen quality parameters, but also protected the stallion sperm from oxidative stress by reducing the levels of reactive oxygen species (ROS) and lipid peroxidation (LPO). The inclusion of 50 mM trehalose in semen extender resulted in significantly (P < .05) increased post-thaw progressive motility and viability compared to the control group. Mares inseminated with frozen-thawed semen supplemented with 50 mM trehalose tended to have better pregnancy rates than controls (non-significant [P < .05]) although a larger fertility trial is required to determine if this effect reaches the level of significance. In conclusion, addition of 50 mM trehalose yielded in better quality stallion semen after cooling and post-thawing in terms of reducing the oxidative stress and enhancing the motility, integrities of acrosome, plasma membrane, mitochondrial potential and DNA.

Effects of soil particle size and gradation on the transformation between shallow phreatic water and soil water under laboratory freezing-thawing action

The transformation between shallow phreatic water and soil water during the freezing-thawing period affects the accurate evaluation of water resources and aggravates soil salinization. In laboratory freezing-thawing experiments, constant temperature freezing at − 10, −20, and − 25 °C was conducted for 62 successive days, and natural thawing was conducted for 13 days, with a groundwater table depth of 1.0 m. The variations in the soil temperature, upward migration amount of phreatic water to soil water (UMA), and downward movement amount of soil water to phreatic water (DMA) of soil columns with particle sizes of d50 = 0.3 mm (A1), d50 = 0.75 mm (B1), d50 = 1.25 mm (C1), d50 = 1.75 mm (D1), and d50 = 2.25 mm (E1) and different particle gradations with inhomogeneity coefficients of 3.47 (A2), 4.69 (B2), 8.31 (C2), 14.67 (D2), and 19.08 (E2) were analyzed. The results showed that the soil temperature was more variable and reached stability earlier as the soil particle size or inhomogeneity coefficient increased. The cumulative UMA decreased as the soil particle size increased and the inhomogeneity coefficient decreased during the freezing process. For the constant temperature freezing at − 10, −20, and − 25 °C, the cumulative UMA and average soil particle size were fitted using an exponential function, but the effect of the soil particle size on the UMA gradually weakened as the freezing air temperature decreased. The daily DMA decreased as the soil particle size decreased, and the particle gradation improved during days 0–5 of the thawing stage, while the cumulative DMA increased as the soil particle size decreased and the inhomogeneity coefficient increased after days 9–10 during the thawing stage. The groundwater was in a negative equilibrium under freezing-thawing action, and the consumption of groundwater was greater when the average soil particle size was smaller and the inhomogeneity coefficient was larger during the freezing-thawing process. The results of this study have important significance for soil salinization prevention and the scientific evaluation of water resources.