Coupling of the Calculated Freezing and Thawing Front Parameterization in the Earth System Model CAS-ESM

The soil freezing and thawing process affects soil physical properties,such as heat conductivity,heat capacity,and hydraulic conductivity in frozen ground regions,and further affects the processes of soil energy,hydrology,and carbon and nitrogen cycles.In this study,the calculation of freezing and thawing front parameterization was implemented into the earth system model of the Chinese Academy of Sciences(CAS-ESM)and its land component,the Common Land Model(CoLM),to investigate the dynamic change of freezing and thawing fronts and their effects.Our results showed that the developed models could reproduce the soil freezing and thawing process and the dynamic change of freezing and thawing fronts.The regionally averaged value of active layer thickness in the permafrost regions was 1.92 m,and the regionally averaged trend value was 0.35 cm yr–1.The regionally averaged value of maximum freezing depth in the seasonally frozen ground regions was 2.15 m,and the regionally averaged trend value was–0.48 cm yr–1.The active layer thickness increased while the maximum freezing depth decreased year by year.These results contribute to a better understanding of the freezing and thawing cycle process.

Mechanics Behavior of Ultra High Toughness Cementitious Composites after Freezing and Thawing

Mechanical behaviors of UHTCC after freezing and thawing were investigated,and compared with those of steel fiber reinforced concrete（SFRC）,air-entrained concrete（AEC） and ordinary concrete（OC）.Four point bending tests had been applied after different freezing-thawing cycles（0,50,100,150,200 and 300 cycles,respectively）.The results showed that residual flexural strength of UHTCC after 300 freezing-thawing cycles was 10.62 MPa（70% of no freezing thawing ones）,while 1.58 MPa（17% of no freezing thawing ones） for SFRC.Flexural toughness of UHTCC decreased by 17%,while 70% for SFRC comparatively.It has been demonstrated experimentally that UHTCC without any air-entraining agent could resist freezing-thawing and retain its high toughness characteristic in cold environment.Consequently,UHTCC could be put into practice for new-built or retrofit of infrastructures in cold regions.

Influences of Seasonal Freezing and Thawing on Soil Water-stable Aggregates in Orchard in High Cold Region,Northeast China

Soil aggregate stability,as an important indicator of soil functions,may be affected by seasonal freezing and thawing(SFT)and land use in high cold and wet regions.Therefore,comprehensive understanding the effects of SFT on aggregate stability in orchards during winter and spring is crucial to develop appropriate management strategies that can effectively alleviate the degradation of soil quality to ensure sustainable development of orchard ecosystems.To determine the mechanism of degradation in orchard soil quality,the effects of SFT on the stability of water-stable aggregates were examined in apple-pear orchards(Pyrus ussuriensis var.ovoidea)of four different ages(11,25,40,and 63 yr)on 0 to 5%slopes before freezing and after thawing from October 2015 to June 2016 in Longjing City,Yanbian Prefecture,Northeast China,involving a comparison of planted versus adjacent uncultivated lands(control).Soil samples were collected to investigate water-stable aggregate stability in three incremental soil layers(0–20,20–40 and 40–60 cm).In the same samples,iron oxide,organic matter,and clay contents of the soil were also determined.Results showed that the destructive influences of SFT on water-stable aggregates were more pronounced with the increased orchards ages,and SFT exerted severe effects on water-stable aggregates of older orchards(40 and 63 yr)than juvenile orchards.Undergoing SFT,the soil instability index and the percentage of aggregate destruction increased by mean 0.15 mm and 1.86%,the degree of aggregation decreased by mean 1.32%,and the erosion resistance weakened,which consequently led to aggregate stability decreased.In addition,soil free,amorphous,and crystalline iron oxide as well as soil organic matter and clay contents are all important factors affecting the stability of water-stable aggregates,and their changes in their contents were consistent with those in the stability of water-stable aggregates.The results of this study suggest that long-term planting fruit trees can exacerbate the damaging effects of SFT on aggregate stability and further soil erosion increases and nutrient losses in an orchard,which hider sustainable use of soil and the productivity orchards.

Stress-Strain Relationship and Failure Criterion for Concrete after Freezing and Thawing Cycles

The research of the failure criterion and one-dimensional stress-strain relationship of deteriorated concrete were carried out. Based on the damage mechanics theory, the dsmage which reflects the alternation of internal state of material were introduced into the formula presented by Desayi and Krishman and the weighted twin-shear strength theory. As a nondestructive examination method in common use, the ultrasonic technique was adopted in the study, and the ultrasonic velocity was used to establish the damage variable. After that, the failure criterion and one-dimensional stress-strain relationship for deteriorated concrete were obtained. Eventually, tests were carried out to study the evolution laws on the damage. The results show that the more freezing and thawing cycles are, the more apparently the failure surface shrinks. Meanwhile, the comparison between theoretical data and experimental data verifies tile rationality of tile damage-based one-dimensional stress-strain relationship proposed.

How freezing and thawing processes affect black-soil aggregate stability in northeastern China

Laboratory experiments were carried out to investigate the effect of freezing and thawing processes on wet aggregate stability （WAS） of black soil. Wet aggregate stability was determined by different aggregate size groups, different water contents, various freeze-thaw cycles, and various freezing temperatures. The results showed that, when at suitable water content, aggregate stability was enhanced, aggregate sta-bility will be disrupted when moisture content is too high or too low, especially higher water content. Temperature also had a significant ef-fect, but moisture content determined the suitable freezing temperatures for a given soil. Water-stable aggregate （WSA〉0.5）, the total aggre-gate content, and mean weight diameter decreasing with the freeze-thaw cycles increase, reached to 5 percent significance level. The reason for crumbing aggregates is the water and air conflict, thus raising the hypothesis that water content affects the aggregate stability in the process of freezing and thawing.

Alternate freezing and thawing enhanced the sediment and nutrient runoff loss in the restored soil of the alpine mining area

This study highlights the influence of freezing-thawing processes on soil erosion in an alpine mine restoration area. Accordingly, a series of simulation experiments were conducted to investigate runoff, sediment, and nutrient losses, and potential influencing factors under freeze-thaw(FT) conditions. Three FT treatments(i.e., 0, 3, and 5 FT cycles), and two soil moisture contents(SMCs;i.e., 10% and 20% SMC on a gravimetric basis) were assessed. The runoff, sediment yield, ammonia nitrogen(AN), nitrate nitrogen(NN), total phosphorus(TP), and dissolved phosphorus(DP) losses from runoff were characterized under different rainfall durations. The fitting results indicated that the runoff rate and sediment rate, AN, NN, TP, and DP concentrations in runoff could be described by exponential functions. FT action increased the total runoff volume and sediment yield by 14.6%–26.0% and 8.8%–35.2%, respectively. The runoff rate and sediment rate increased rapidly with the increment of FT cycles before stabilizing. At 20% SMC, the total runoff volume and sediment yield were significantly higher than those at 10% SMC. The loss curves of AN and NN concentrations varied due to differences in their chemical properties. FT action and high SMC promoted AN and NN losses, whereas the FT cycles had little effect. FT action increased TP and DP losses by 60.2%–220.1% and 48.4%–129.8%, respectively, compared to cases with no FT action;the highest TP and DP losses were recorded at 20% SMC. This study provides a deep understanding of freezing-thawing mechanisms in the soils of alpine mine restoration areas and the influencing factors of these mechanisms on soil erosion, thereby supporting the development of erosion prevention and control measures in alpine mine restoration areas.

A model of unfrozen water content in rock during freezing and thawing with experimental validation by nuclear magnetic resonance

The unfrozen water content of rock during freezing and thawing has an important influence on its physical and mechanical properties.This study presented a model for calculating the unfrozen water content of rock during freezing and thawing process,considering the influence of unfrozen water film and rock pore structure,which can reflect the hysteresis and super-cooling effects.The pore size distribution cu rves of red sandsto ne and its unfrozen water conte nt under different temperatures during the freezing and thawing process were measured using nuclear magnetic resonance(NMR) to validate the proposed model.Comparison between the experimental and calculated results indicated that the theoretical model accu rately reflected the water content change law of red sandstone during the freezing and thawing process.Furthermore,the influences of Hamaker constant and surface relaxation parameter on the model results were examined.The results showed that the appropriate magnitude order of Hamaker constant for the red sandstone was 10J to 10J;and when the relaxation parameter of the rock surface was within 25-30 μm/ms,the calculated unfrozen water content using the proposed model was consistent with the experimental value.

Effect of the frozen layer on the stability of cut soil slopes during seasonal freezing and thawing

Research on the stability of soil slopes in seasonally frozen regions has mainly focused on slope failures during the thawing window.There are few studies on slope stability during the freezing window and its subsequent influence on slope failure in the next thawing window.In this paper,soil strength was tested during freezing and thawing to obtain temperature-dependent strength parameters for the simulation of slope stability.Then,the slope's temperature field over an entire year was accurately simulated so that characteristics of the frozen layer could be determined at any time.Based on the above results,the progressive failure modes of frozen soil slopes are discussed.The results show that:1)during the freezing window,depth of the frozen soil layer increases,as does the slope's safety factor,while a yield zone propagates towards the slope shoulder.(2)During the thawing window,the frozen soil layer shrinks in depth while the yield zone continuously expands,which decreases the safety factor.Comprehensive analysis of these results indicate that the frozen layer provides a“toe-locking effect”that increases the safety factor during the freezing window,while it also provides a“dragging effect”that propagates the yield zone towards the slope shoulder.During the thawing window,the“toe-locking effect”gradually diminishes;a continuous sliding surface is formed,which lead to a landslide.The frozen soil layer of the freezing window accelerates the slope sliding in the thawing window.

The Relations of Change Rate of Constitutive Variables for the Freezing and Thawing of Water Saturated Porous Media

The relations of change rate of an independent variable, volumetric strain of the porous skeleton, with the change rates of a kind of constitutive variables, such as porosity, volumetric strain of the solid matrix, are derived from the definition of the porosity of water saturated porous media; and the relations of the change rates of another two independent variables, pressure of the pore liquid water and temperature, with the change rates of another kind of constitutive variables, such as pressure of the pore ice, average pressure of the pore liquid water and ice, and average stress of the solid matrix, are obtained from the Clausius Clapeyron relation in the process of freezing or thawing, definitions of the average pore pressure and effective stress. Based on the hypothesis of linear thermoelasticity, principle of effective stress and these relations, the change rates of all constitutive variables may be described with the change rates of the three independent variables.

Variations and trends of the freezing and thaw- ing index along the Qinghai-Xizang Railway for 1966-2004

Annual freezing and thawing index of 7 meteorological stations along the Qing- hai-Xizang Railway were calculated based on daily maximum and minimum temperature records for 1966-2004. Trends of annual freezing and thawing index were analyzed using the Mann-Kendall test and a simple linear regression method. The results show that： 1） The mean annual freezing indices range from 95 to 2300℃·d and the mean annual thawing indices range from 630 to 3250℃·d. The mean annual freezing index of the 7 stations exhibited decreasing trends with decreasing rate of -16.6- -59.1 ℃·d/10a. The mean annual thawing index of these 7 stations showed increasing trends with the related decreasing rate is 19.83-45.6℃·d/10a. 2） The MK trend test indicated the significant decreasing trends （significant at 〈 0.05 significant level） in the annual freezing index for most stations except for Golmud. The significant increasing trends can be observed in the annual thawing index for 4 stations except Golmud and Tuotuohe. Golmud was the only station with no trends in both annual freezing and annual thawing index.

Study on the Possibility of Raw Seawater into Drinking Water—A Religious Water Literacy

This paper explores the conversion of raw seawater into drinking water from a religious water literacy (RWL) perspective. RWL is here defined as a socially just water literacy that is based on the respect for the dignity of life of all living beings on the Earth. It discusses the importance of sustainable water sources and proposes purification methods. That is, the study aims to show a brief outline of the drinking water source (inland waters;mainly river water) and their purification technologies in recent times and today and propose the purification method (Freezing-Thawing-UV method) in case of taking the seawater as the source. And, it emphasizes the need for dialogue and cooperation between countries in order to proceed. The paper also discusses the relationship among religion, culture, and civilization, and highlights the similarities between Marx’s historical materialism and Umesao’s ecological view. It further discusses the importance of water purification technology, separation methods, and the potential for seawater as an energy source. The paper concludes by discussing the importance of dialogue, communication and understanding environmental decision-making. In order to carry them forward, it is convinced that citizens in the world are nothing but people with self-awareness of “Bodhisattvas of the Earth” as identities. As a result, the new findings that suggest the possibility of raw seawater into drinking water from a religious water literacy perspective through the lens of Kawakatsu’s maritime view have been obtained.

Update on techniques for cryopreservation of human spermatozoa

In the 1960s,sperm cryopreservation was developed as a method to preserve fertility.Currently,techniques for the cryopreservation of human spermatozoa have been widely used in assisted reproduction.However,although sperm cryobiology has made notable achievements,the optimal method for the recovery of viable spermatozoa after cryopreservation remains elusive.Postthawing sperm quality can be affected by cryoprotectants,ice formation,storage conditions,and osmotic stress during the freezing process.This review discusses recent advances in different cryopreservation techniques,cryoprotectants,and freezing and thawing methods during cryopreservation and new indications for the use of cryopreserved spermatozoa.