Energy and resources including coal, oil, and gas are in demand all over the world. Because these resources near the earth's surface have been exploited for many years, the extraction depth has increased.As mining...Energy and resources including coal, oil, and gas are in demand all over the world. Because these resources near the earth's surface have been exploited for many years, the extraction depth has increased.As mining shafts in the coal extraction process become deeper, especially in western China, an artificial freezing method is used and is concentrated in the fractured rock mass. The frost-heaving pressure(FHP)is directly related to the degree of damage of the fractured rock mass. This paper is focused on FHP during the freezing process, with emphasis on the frost-heaving phenomenon in engineering materials. A review of the frost phenomenon in the geotechnical engineering literature indicates that:(1) During the soil freezing process, the ice content that is influenced by unfrozen water and the freezing rate are the determining factors of FHP;(2) During the freezing process of rock and other porous media, the resulting cracks should be considered because the FHP may damage the crack structure;(3) The FHP in a joint rock mass is analyzed by the joint deformation in field and experimental tests and can be simulated by the equivalent expansion method including water migration and joint deformation.展开更多
To investigate the frost-heave properties of silty clay under the combination action of seasonal freezing and artificial freezing, and verify the feasibility of combined freezing, eight combined freezing experiments w...To investigate the frost-heave properties of silty clay under the combination action of seasonal freezing and artificial freezing, and verify the feasibility of combined freezing, eight combined freezing experiments were performed on silty clay with water content (mass fraction) of 23.5% and 28.0%, through developed frost-heave test apparatus, in closed or open system. Two sorts of freezing temperature models, namely, constant and sine models, were applied to artificial freezing. The experimental results indicate that the frost-heave degree in seasonal freezing stage accounts for over 90% of the total in open system and it is up to 95% in closed system; the change of artificial sine-freezing temperature has no influence on the frost-heave degree in closed system, however, slight influence in open system. It is found that the variation of temperature gradient of sine-freezing specimen lags behind that of sine-freezing temperature with half phase; sine-freezing temperature model can reduce frost-heave degree of soil. Brand new technology is proposed for the application of artificial ground freezing and new study field of artificial freezing is created.展开更多
The calculation of frost heaving with ice lens formation is still not standard for construction projects using artificial ground freezing(AGF).In fine-grained material,ice lenses may initiate and lead to significant h...The calculation of frost heaving with ice lens formation is still not standard for construction projects using artificial ground freezing(AGF).In fine-grained material,ice lenses may initiate and lead to significant heaving at the ground surface,which should be considered in advance.However,the complex processes during ice lens formation are still not fully understood and difficult to capture in a simple approach.In the past,the semi-analytical approach of Konrad and Morgenstern used one soil constant,the“segregation potential(SP)”.It has been mainly and most successfully applied to the heave calculation of natural-induced soil freezing in cold regions.Its application to AGF has been so far unsuccessful.To solve this,a new semi-analytical approach is presented in this paper.It includes AGF conditions such as bottom-up freezing,temperature gradients to reach great freezing velocities,and a distinction between two freezing states.One is the freezing-up state until a certain frost body thickness is reached(thermal transient state),and the other is a holding phase where the frost body thickness is kept constant(thermal quasi-steady state).To test its ability,the results are applied to another freezing direction,the top-down freezing.The new approach is validated using two different frost-susceptible soils and,in total,50 frost heave tests.In the thermal transient region,where the SP is applicable,the two semi-analytical approaches are compared,showing improved performance of the current method by about 15%.展开更多
In seasonally frozen regions,the frost-heave properties of soil play a significant role in its upper-structure performance and durability.To investigate the frost-heave behaviors of saturated,compacted silty clay soil...In seasonally frozen regions,the frost-heave properties of soil play a significant role in its upper-structure performance and durability.To investigate the frost-heave behaviors of saturated,compacted silty clay soil widely used as subgrade material,a series of one-side freezing tests was carried out;and the freezing depth and frozen front effected by the compactness,temperature,overburden pressure,and water-supply condition were analyzed and discussed.The results show that the moving speed of the frozen front and growth rate of the frozen depth are positively correlated.The frost heave is maximum in the frost-heave stability condition.The frost ratio of saturated soil is proportional to the water supply and cooling temperature under a one-side freezing condition.The frost ratio of saturated soil is inversely proportional to the initial compactness of the soil specimen and the overburden pressure.展开更多
[Objective]The paper was to explore the influence of near-surface low temperature on cultivation of soft-seed pomegranate,and to provide guidance for planting location of soft-seed pomegranate.[Method]Taking 10 soft-s...[Objective]The paper was to explore the influence of near-surface low temperature on cultivation of soft-seed pomegranate,and to provide guidance for planting location of soft-seed pomegranate.[Method]Taking 10 soft-seed pomegranate planting plots under different site conditions as the research objects,the near-surface low temperature of 45-50 cm was dynamically monitored from December 1,2018 to February 20,2019,and comparative analysis was made based on the local meteorological data over the same period.[Result]The near-surface low temperature of each temperature monitoring point was lower than the local meteorological data,which were all in the range of low temperature causing freezing in-jury of pomegranate trees,but the degree of freezing injury was different.The variation of near-surface low temperature was positively correlated with the altitude of terrain,but negatively correlated with the difference of topography and landform.When the local topography and landform were similar,the accumulation time of near-surface low temperature was negatively correlated with the altitude of terrain,while the duration of low tem-perature directly affected the degree of freezing injury.[Conclusion]The development of soft-seed pomegranate cultivation in Tunisia along Huang Mangling region in Henan Province refers to the local meteorological data.Meantime,it is also necessary to pay attention to the impact of regional microclimate environment,especially early monitoring of near-surface temperature to select suitable site and natural conditions.展开更多
Artificial freezing of water-bearing soil layers composing a sedimentary deposit can induce frost heave and water migration that affect the natural stress-strain state of the soil layers and freezing process.In the pr...Artificial freezing of water-bearing soil layers composing a sedimentary deposit can induce frost heave and water migration that affect the natural stress-strain state of the soil layers and freezing process.In the present paper,a thermo-hydro-mechanical(THM)model for freezing of water-saturated soil is proposed to study the effects of frost heave and water migration in frozen soils on the formation of a frozen wall and subsequent excavation activity for sinking a vertical shaft.The governing equations of the model are formulated relative to porosity,temperature,and displacement which are considered as primary variables.The relationship between temperature,pore water,and ice pressure in frozen soil is established by the Clausius-Clapeyron equation,whereas the interaction between the stress-strain behavior and changes in porosity and pore pressure is described with the poromechanics theory.Moreover,constitutive relations for additional mechanical deformation are incorporated to describe volumetric expansion of soil during freezing as well as creep strain of soil in the frozen state.The ability of the proposed model to capture the frost heave of frozen soil is demonstrated by a comparison between numerical results and experimental data given by a one-sided freezing test.Also to validate the model in other freezing conditions,a radial freezing experiment is performed.After the validation procedure,the model is applied to numerical simulation of artificial freezing of silt and sand layers for shaft sinking at Petrikov potash mine in Belarus.Comparison of calculated temperature with thermal monitoring data during active freezing stage is presented.Numerical analysis of deformation of unsupported sidewall of a shaft inside the frozen wall is conducted to account for the change in natural stress-strain state of soil layers induced by artificial freezing.展开更多
Non-freezing cold injury is a prevalent cause of peripheral nerve damage, but its pathogenic mechanism is poorly understood, and treatment remains inadequate. Glucocorticoids have anti-inflammatory and lipid peroxidat...Non-freezing cold injury is a prevalent cause of peripheral nerve damage, but its pathogenic mechanism is poorly understood, and treatment remains inadequate. Glucocorticoids have anti-inflammatory and lipid peroxidation-inhibiting properties. We therefore examined whether dexamethasone, a synthetic glucocorticoid compound, would alleviate early-stage non-freezing cold injury of the sciatic nerve. We established Wistar rat models of non-freezing cold injury by exposing the left sciatic nerve to cold(3–5°C) for 2 hours, then administered dexamethasone(3 mg/kg intraperitoneally) to half of the models. One day after injury, the concentration of Evans blue tracer in the injured sciatic nerve of rats that received dexamethasone was notably lower than that in the injured sciatic nerve of rats that did not receive dexamethasone; neither Evans blue dye nor capillary stenosis was observed in the endoneurium, but myelinated nerve fibers were markedly degenerated in the injured sciatic nerve of animals that received dexamethasone. After dexamethasone administration, however, endoneurial vasculopathy was markedly improved, although damage to the myelinated nerve fiber was not alleviated. These findings suggest that dexamethasone protects the blood-nerve barrier, but its benefit in non-freezing cold injury is limited to the vascular system.展开更多
Freeze injury is an usual disaster for winter wheat in Shanxi Province, China, and monitoring freeze injury is of important economic significance. The aim of this article is to monitor and analyze the winter wheat fre...Freeze injury is an usual disaster for winter wheat in Shanxi Province, China, and monitoring freeze injury is of important economic significance. The aim of this article is to monitor and analyze the winter wheat freeze injury using remote sensing data, to monitor the occurrence and spatial distribution of winter wheat freeze in time, as well as the severity of the damage. The winter wheat freeze injury was monitored using multi-temporal moderate-resolution imaging spectroradiometer (MODIS) data, combined with ground meteorological data and field survey data, the change of normalized difference vegetation index (NDVI) before and after freeze injury was analyzed, as well as the effect of winter wheat growth recovery rate on yield. The results showed that the NDVI of winter wheat decreased dramatically after the suffering from freeze injury, which was the prominent feature for the winter wheat freeze injury monitoring. The degrees of winter wheat freeze injury were different in the three regions, of which, Yuncheng was the worst severity and the largest freeze injury area, the severity of freeze injury correlates with the breeding stage of the winter wheat. The yield of winter wheat showed positive correlation with its growth recovery rate (r=0.659^** which can be utilized to monitor the severity of winter wheat freeze injury as well as its impact on yield. It can effectively monitor the occurrence and severity of winter wheat freeze injury using horizontal and vertical profile distribution and growth wheat freeze injury in Shanxi Province. recovery rate, and provide a basis for monitoring the winter展开更多
Under the environment of an artificial climate chamber, supercooling point (SCP) and freezing point (FP) in flower and young fruit at different development stages and freezing injuries of floral organs were studie...Under the environment of an artificial climate chamber, supercooling point (SCP) and freezing point (FP) in flower and young fruit at different development stages and freezing injuries of floral organs were studied. The apricot cultivars tested were Kety, Golden Sun and Honghebao. With the development of flower buds, SCP and FP increased, which indicated that their cold resistance decreased. SCP and FP varied with different floral organs. For different apricot cultivars, it was found that, the lower SCP or FP in floral organs was, the more resistant capacity the cultivar had, and the larger the temperature interval from SCP to FP was. SCP was not a constant value, but a range. Frequency distribution of SCP in petals was more dispersing than that in stamens and pistils. Floral organs could maintain a supercooling state to avoid ice formation, but they were sensitive to freezing. Once floral organs froze, thev turned brown after thawing.展开更多
Frost susceptibility should be considered in the design and construction of foundations and retaining-wall structures in regions with the seasonally freezing-soil ground condition.When planning construction that goes ...Frost susceptibility should be considered in the design and construction of foundations and retaining-wall structures in regions with the seasonally freezing-soil ground condition.When planning construction that goes deep into this soil,one has to understand the impact of horizontal forces to an underground wall and realize the potential effect of frost heaving upon,deep foundations.This article presents a few soil tests for frost heaving and the results of those tests show dangerous data for retaining structures under the soil conditions in Kazakhstan.The main parameters of the soil include frost penetration and heaving rate and amount.So,in designing underground structures,one must understand and consider that frost heaving occurs in various directions;this factor is very important for predicting on the restriction of deformations of structures in the seasonally freezing-soil ground condition.展开更多
Winter wheat freeze injury is one of the main agro-meteorological disasters affecting wheat production. In order to evaluate the severity of freeze injury on winter wheat systematically, we proposed a grey-system mod...Winter wheat freeze injury is one of the main agro-meteorological disasters affecting wheat production. In order to evaluate the severity of freeze injury on winter wheat systematically, we proposed a grey-system model (GSM) to monitor the degree and the distribution of the winter wheat freeze injury. The model combines remote sensing (RS) and geographic information system (GIS) technology. It gave examples of wheat freeze injury monitoring applications in Gaocheng and Jinzhou of Hebei Province, China. We carried out a quantitative evaluation method study on the severity of winter wheat freeze injury. First, a grey relational analysis (GRA) was conducted. At the same time, the weights of the stressful factors were determined. Then a wheat freezing injury stress multiple factor spatial matrix was constructed using spatial interpolation technology. Finally, a winter wheat freeze damage evaluation model was established through grey clustering algorithm (GCA), and classifying the study area into three sub-areas, affected by severe, medium or light disasters. The evaluation model were verified by the Kappa model, the overall accuracy reached 78.82% and the Kappa coefficient was 0.6754. Therefore, through integration of GSM with RS images as well as GIS analysis, quantitative evaluation and study of winter wheat freeze disasters can be conducted objectively and accurately, making the evaluation model more scientific.展开更多
This paper presents various deformation-monitoring technologies employed to monitor the frost heave and thaw settlement of two mounds along the Qinghai–Tibet Engineering Corridor(QTEC), China. The QTEC is known as a ...This paper presents various deformation-monitoring technologies employed to monitor the frost heave and thaw settlement of two mounds along the Qinghai–Tibet Engineering Corridor(QTEC), China. The QTEC is known as a critical infrastructure and passage connecting inland China and the Qinghai–Tibet Plateau(QTP). Three technologies—global navigation satellite system(GNSS), terrestrial laser scanning(TLS), and unmanned aerial vehicle(UAV)—were used to estimate the freeze/thaw–induced 3D surface deformation of two frost mounds. Our results showed that (1) the two frost mounds exhibited mainly thaw settlement in thawing periods and frost heave in the freezing period, but frost heave dominated after repeated freeze–thaw cycles;(2) different zones of the mounds showed different deformation characteristics;(3) active-layer thickness(ALT) and elevation changes were highly correlated during thaw periods;(4) integrated 3D-measurement technologies can achieve a better understanding and assessment of hazards in the permafrost area.展开更多
Sperm freezing is widely used in ART clinics around the globe. Very little has actually changed with respect to cryopreservation protocols and methodology of freezing over the last 50 years. The aim of this paper is t...Sperm freezing is widely used in ART clinics around the globe. Very little has actually changed with respect to cryopreservation protocols and methodology of freezing over the last 50 years. The aim of this paper is to briefly review the basic principles that underlie freezing and ice crystal formation and also provide a brief overview of newer sperm freezing techniques like sperm vitrification and freeze drying of sperm.展开更多
Freeze-sealing pipe roof method is applied in the Gongbei tunnel,which causes the ground surface uplift induced by frost heave.A frost heaving prediction approach based on the coefficient of cold expansion is proposed...Freeze-sealing pipe roof method is applied in the Gongbei tunnel,which causes the ground surface uplift induced by frost heave.A frost heaving prediction approach based on the coefficient of cold expansion is proposed to simulate the ground deformation of the Gongbei tunnel.The coefficient of cold expansion in the model and the frost heaving rate from the frost heave test under the hydration condition can achieve a good correspondence making the calculation result closer to the actual engineering.The ground surface uplift along the lateral and longitudinal direction are respectively analyzed and compared with the field measured data to validate the model.The results show that a good agreement between the frost heaving prediction model and the field measured data verifies the rationality and applicability of the proposed model.The maximum uplift of the Gongbei tunnel appears at the center of the model,gradually decreasing along with the lateral and longitudinal directions.The curve in the lateral direction presents a normal distribution due to the influence of the constraint of two sides,while the one along the lateral direction shapes like a parabola with the opening downward due to the temperature field distribution.The model provides a reference for frost heaving engineering calculation.展开更多
Determining the suitable areas for winter wheat under climate change and assessing the risk of freezing injury are crucial for the cultivation of winter wheat.We used an optimized Maximum Entropy(MaxEnt)Model to predi...Determining the suitable areas for winter wheat under climate change and assessing the risk of freezing injury are crucial for the cultivation of winter wheat.We used an optimized Maximum Entropy(MaxEnt)Model to predict the potential distribution of winter wheat in the current period(1970-2020)and the future period(2021-2100)under four shared socioeconomic pathway scenarios(SSPs).We applied statistical downscaling methods to downscale future climate data,established a scientific and practical freezing injury index(FII)by considering the growth period of winter wheat,and analyzed the characteristics of abrupt changes in winter wheat freezing injury by using the Mann-Kendall(M-K)test.The results showed that the prediction accuracy AUC value of the MaxEnt Model reached 0.976.The minimum temperature in the coldest month,precipitation in the wettest season and annual precipitation were the main factors affecting the spatial distribution of winter wheat.The total suitable area of winter wheat was approximately 4.40×10^(7)ha in the current period.In the 2070s,the moderately suitable areas had the greatest increase by 9.02×10^(5)ha under SSP245 and the least increase by 6.53×10^(5)ha under SSP370.The centroid coordinates of the total suitable areas tended to move northward.The potential risks of freezing injury in the high-latitude and-altitude areas of the Loess Plateau,China increased significantly.The northern areas of Xinzhou in Shanxi Province,China suffered the most serious freezing injury,and the southern areas of the Loess Plateau suffered the least.Environmental factors such as temperature,precipitation and geographical location had important impacts on the suitable area distribution and freezing injury risk of winter wheat.In the future,greater attention should be paid to the northward boundaries of both the winter wheat planting areas and the areas of freezing injury risk to provide the early warning of freezing injury and implement corresponding management strategies.展开更多
基金financial assistance provided by the National Natural Science Foundation of China (Nos. B14021 and 51304209)the Science Foundation of Jiangsu (No. 16KJB580014)
文摘Energy and resources including coal, oil, and gas are in demand all over the world. Because these resources near the earth's surface have been exploited for many years, the extraction depth has increased.As mining shafts in the coal extraction process become deeper, especially in western China, an artificial freezing method is used and is concentrated in the fractured rock mass. The frost-heaving pressure(FHP)is directly related to the degree of damage of the fractured rock mass. This paper is focused on FHP during the freezing process, with emphasis on the frost-heaving phenomenon in engineering materials. A review of the frost phenomenon in the geotechnical engineering literature indicates that:(1) During the soil freezing process, the ice content that is influenced by unfrozen water and the freezing rate are the determining factors of FHP;(2) During the freezing process of rock and other porous media, the resulting cracks should be considered because the FHP may damage the crack structure;(3) The FHP in a joint rock mass is analyzed by the joint deformation in field and experimental tests and can be simulated by the equivalent expansion method including water migration and joint deformation.
基金Project(40571032) supported by the National Natural Science Foundation of ChinaProject(2006G011-B-3) supported by Science Studies and Development Plan Foundation of Railway Ministry
文摘To investigate the frost-heave properties of silty clay under the combination action of seasonal freezing and artificial freezing, and verify the feasibility of combined freezing, eight combined freezing experiments were performed on silty clay with water content (mass fraction) of 23.5% and 28.0%, through developed frost-heave test apparatus, in closed or open system. Two sorts of freezing temperature models, namely, constant and sine models, were applied to artificial freezing. The experimental results indicate that the frost-heave degree in seasonal freezing stage accounts for over 90% of the total in open system and it is up to 95% in closed system; the change of artificial sine-freezing temperature has no influence on the frost-heave degree in closed system, however, slight influence in open system. It is found that the variation of temperature gradient of sine-freezing specimen lags behind that of sine-freezing temperature with half phase; sine-freezing temperature model can reduce frost-heave degree of soil. Brand new technology is proposed for the application of artificial ground freezing and new study field of artificial freezing is created.
基金supported by the German Research Foundation(DFG)under the project“Investigation and calculation of frost heave considering specific boundary conditions of ground freezing”(Grant No.409760547).
文摘The calculation of frost heaving with ice lens formation is still not standard for construction projects using artificial ground freezing(AGF).In fine-grained material,ice lenses may initiate and lead to significant heaving at the ground surface,which should be considered in advance.However,the complex processes during ice lens formation are still not fully understood and difficult to capture in a simple approach.In the past,the semi-analytical approach of Konrad and Morgenstern used one soil constant,the“segregation potential(SP)”.It has been mainly and most successfully applied to the heave calculation of natural-induced soil freezing in cold regions.Its application to AGF has been so far unsuccessful.To solve this,a new semi-analytical approach is presented in this paper.It includes AGF conditions such as bottom-up freezing,temperature gradients to reach great freezing velocities,and a distinction between two freezing states.One is the freezing-up state until a certain frost body thickness is reached(thermal transient state),and the other is a holding phase where the frost body thickness is kept constant(thermal quasi-steady state).To test its ability,the results are applied to another freezing direction,the top-down freezing.The new approach is validated using two different frost-susceptible soils and,in total,50 frost heave tests.In the thermal transient region,where the SP is applicable,the two semi-analytical approaches are compared,showing improved performance of the current method by about 15%.
基金supported by the National Key Basic Research Development Plan (2012CB026104)the National Natural Science Foundation of China (Nos. 51408163 and 51578200)+1 种基金the Natural Science Foundation of Heilongjiang Province (No. ZD201218)the Research Foundation of Fuzhou University (510406)
文摘In seasonally frozen regions,the frost-heave properties of soil play a significant role in its upper-structure performance and durability.To investigate the frost-heave behaviors of saturated,compacted silty clay soil widely used as subgrade material,a series of one-side freezing tests was carried out;and the freezing depth and frozen front effected by the compactness,temperature,overburden pressure,and water-supply condition were analyzed and discussed.The results show that the moving speed of the frozen front and growth rate of the frozen depth are positively correlated.The frost heave is maximum in the frost-heave stability condition.The frost ratio of saturated soil is proportional to the water supply and cooling temperature under a one-side freezing condition.The frost ratio of saturated soil is inversely proportional to the initial compactness of the soil specimen and the overburden pressure.
文摘[Objective]The paper was to explore the influence of near-surface low temperature on cultivation of soft-seed pomegranate,and to provide guidance for planting location of soft-seed pomegranate.[Method]Taking 10 soft-seed pomegranate planting plots under different site conditions as the research objects,the near-surface low temperature of 45-50 cm was dynamically monitored from December 1,2018 to February 20,2019,and comparative analysis was made based on the local meteorological data over the same period.[Result]The near-surface low temperature of each temperature monitoring point was lower than the local meteorological data,which were all in the range of low temperature causing freezing in-jury of pomegranate trees,but the degree of freezing injury was different.The variation of near-surface low temperature was positively correlated with the altitude of terrain,but negatively correlated with the difference of topography and landform.When the local topography and landform were similar,the accumulation time of near-surface low temperature was negatively correlated with the altitude of terrain,while the duration of low tem-perature directly affected the degree of freezing injury.[Conclusion]The development of soft-seed pomegranate cultivation in Tunisia along Huang Mangling region in Henan Province refers to the local meteorological data.Meantime,it is also necessary to pay attention to the impact of regional microclimate environment,especially early monitoring of near-surface temperature to select suitable site and natural conditions.
基金supported by 17-11-01204 project(Russian Science Foundation)。
文摘Artificial freezing of water-bearing soil layers composing a sedimentary deposit can induce frost heave and water migration that affect the natural stress-strain state of the soil layers and freezing process.In the present paper,a thermo-hydro-mechanical(THM)model for freezing of water-saturated soil is proposed to study the effects of frost heave and water migration in frozen soils on the formation of a frozen wall and subsequent excavation activity for sinking a vertical shaft.The governing equations of the model are formulated relative to porosity,temperature,and displacement which are considered as primary variables.The relationship between temperature,pore water,and ice pressure in frozen soil is established by the Clausius-Clapeyron equation,whereas the interaction between the stress-strain behavior and changes in porosity and pore pressure is described with the poromechanics theory.Moreover,constitutive relations for additional mechanical deformation are incorporated to describe volumetric expansion of soil during freezing as well as creep strain of soil in the frozen state.The ability of the proposed model to capture the frost heave of frozen soil is demonstrated by a comparison between numerical results and experimental data given by a one-sided freezing test.Also to validate the model in other freezing conditions,a radial freezing experiment is performed.After the validation procedure,the model is applied to numerical simulation of artificial freezing of silt and sand layers for shaft sinking at Petrikov potash mine in Belarus.Comparison of calculated temperature with thermal monitoring data during active freezing stage is presented.Numerical analysis of deformation of unsupported sidewall of a shaft inside the frozen wall is conducted to account for the change in natural stress-strain state of soil layers induced by artificial freezing.
基金supported by grants from"Shihuida"Scientific Research Program of Sichuan Province Medical Association of China,No.SHD12-21Medical Scientific Research Program of Health Bureau of Yibin City in China
文摘Non-freezing cold injury is a prevalent cause of peripheral nerve damage, but its pathogenic mechanism is poorly understood, and treatment remains inadequate. Glucocorticoids have anti-inflammatory and lipid peroxidation-inhibiting properties. We therefore examined whether dexamethasone, a synthetic glucocorticoid compound, would alleviate early-stage non-freezing cold injury of the sciatic nerve. We established Wistar rat models of non-freezing cold injury by exposing the left sciatic nerve to cold(3–5°C) for 2 hours, then administered dexamethasone(3 mg/kg intraperitoneally) to half of the models. One day after injury, the concentration of Evans blue tracer in the injured sciatic nerve of rats that received dexamethasone was notably lower than that in the injured sciatic nerve of rats that did not receive dexamethasone; neither Evans blue dye nor capillary stenosis was observed in the endoneurium, but myelinated nerve fibers were markedly degenerated in the injured sciatic nerve of animals that received dexamethasone. After dexamethasone administration, however, endoneurial vasculopathy was markedly improved, although damage to the myelinated nerve fiber was not alleviated. These findings suggest that dexamethasone protects the blood-nerve barrier, but its benefit in non-freezing cold injury is limited to the vascular system.
基金supported by grants from the Key Tech-nologies R&D Program of Shanxi Province, China(20060311140)the Open Project Program of Weather Bureau of Shanxi Province, China (SX053001)
文摘Freeze injury is an usual disaster for winter wheat in Shanxi Province, China, and monitoring freeze injury is of important economic significance. The aim of this article is to monitor and analyze the winter wheat freeze injury using remote sensing data, to monitor the occurrence and spatial distribution of winter wheat freeze in time, as well as the severity of the damage. The winter wheat freeze injury was monitored using multi-temporal moderate-resolution imaging spectroradiometer (MODIS) data, combined with ground meteorological data and field survey data, the change of normalized difference vegetation index (NDVI) before and after freeze injury was analyzed, as well as the effect of winter wheat growth recovery rate on yield. The results showed that the NDVI of winter wheat decreased dramatically after the suffering from freeze injury, which was the prominent feature for the winter wheat freeze injury monitoring. The degrees of winter wheat freeze injury were different in the three regions, of which, Yuncheng was the worst severity and the largest freeze injury area, the severity of freeze injury correlates with the breeding stage of the winter wheat. The yield of winter wheat showed positive correlation with its growth recovery rate (r=0.659^** which can be utilized to monitor the severity of winter wheat freeze injury as well as its impact on yield. It can effectively monitor the occurrence and severity of winter wheat freeze injury using horizontal and vertical profile distribution and growth wheat freeze injury in Shanxi Province. recovery rate, and provide a basis for monitoring the winter
文摘Under the environment of an artificial climate chamber, supercooling point (SCP) and freezing point (FP) in flower and young fruit at different development stages and freezing injuries of floral organs were studied. The apricot cultivars tested were Kety, Golden Sun and Honghebao. With the development of flower buds, SCP and FP increased, which indicated that their cold resistance decreased. SCP and FP varied with different floral organs. For different apricot cultivars, it was found that, the lower SCP or FP in floral organs was, the more resistant capacity the cultivar had, and the larger the temperature interval from SCP to FP was. SCP was not a constant value, but a range. Frequency distribution of SCP in petals was more dispersing than that in stamens and pistils. Floral organs could maintain a supercooling state to avoid ice formation, but they were sensitive to freezing. Once floral organs froze, thev turned brown after thawing.
文摘Frost susceptibility should be considered in the design and construction of foundations and retaining-wall structures in regions with the seasonally freezing-soil ground condition.When planning construction that goes deep into this soil,one has to understand the impact of horizontal forces to an underground wall and realize the potential effect of frost heaving upon,deep foundations.This article presents a few soil tests for frost heaving and the results of those tests show dangerous data for retaining structures under the soil conditions in Kazakhstan.The main parameters of the soil include frost penetration and heaving rate and amount.So,in designing underground structures,one must understand and consider that frost heaving occurs in various directions;this factor is very important for predicting on the restriction of deformations of structures in the seasonally freezing-soil ground condition.
基金supported by the National Natural Science Foundation of China (41101395, 41101397 and 41001199)the Beijing New Star Project on Science & Technology,China (2010B024)the Key Technologies R&D Program of China during the 12th Five-Year Plan period(2012BAH29B04)
文摘Winter wheat freeze injury is one of the main agro-meteorological disasters affecting wheat production. In order to evaluate the severity of freeze injury on winter wheat systematically, we proposed a grey-system model (GSM) to monitor the degree and the distribution of the winter wheat freeze injury. The model combines remote sensing (RS) and geographic information system (GIS) technology. It gave examples of wheat freeze injury monitoring applications in Gaocheng and Jinzhou of Hebei Province, China. We carried out a quantitative evaluation method study on the severity of winter wheat freeze injury. First, a grey relational analysis (GRA) was conducted. At the same time, the weights of the stressful factors were determined. Then a wheat freezing injury stress multiple factor spatial matrix was constructed using spatial interpolation technology. Finally, a winter wheat freeze damage evaluation model was established through grey clustering algorithm (GCA), and classifying the study area into three sub-areas, affected by severe, medium or light disasters. The evaluation model were verified by the Kappa model, the overall accuracy reached 78.82% and the Kappa coefficient was 0.6754. Therefore, through integration of GSM with RS images as well as GIS analysis, quantitative evaluation and study of winter wheat freeze disasters can be conducted objectively and accurately, making the evaluation model more scientific.
基金supported by the National Natural Science Foundation of China (41301508, 41630636)
文摘This paper presents various deformation-monitoring technologies employed to monitor the frost heave and thaw settlement of two mounds along the Qinghai–Tibet Engineering Corridor(QTEC), China. The QTEC is known as a critical infrastructure and passage connecting inland China and the Qinghai–Tibet Plateau(QTP). Three technologies—global navigation satellite system(GNSS), terrestrial laser scanning(TLS), and unmanned aerial vehicle(UAV)—were used to estimate the freeze/thaw–induced 3D surface deformation of two frost mounds. Our results showed that (1) the two frost mounds exhibited mainly thaw settlement in thawing periods and frost heave in the freezing period, but frost heave dominated after repeated freeze–thaw cycles;(2) different zones of the mounds showed different deformation characteristics;(3) active-layer thickness(ALT) and elevation changes were highly correlated during thaw periods;(4) integrated 3D-measurement technologies can achieve a better understanding and assessment of hazards in the permafrost area.
文摘Sperm freezing is widely used in ART clinics around the globe. Very little has actually changed with respect to cryopreservation protocols and methodology of freezing over the last 50 years. The aim of this paper is to briefly review the basic principles that underlie freezing and ice crystal formation and also provide a brief overview of newer sperm freezing techniques like sperm vitrification and freeze drying of sperm.
基金supported by the financial support from National Natural Science Foundation of China(No.51478340)Natural Science Foundation of Jiangsu Province(No.BK20200707)+4 种基金The Natural Science Foundation of the Jiangsu Higher Education Institutions of China(No.20KJB560029)China Postdoctoral Science Foundation(No.2020M671670)Key Laboratory of Soft Soils and Geoenvironmental Engineering(Zhejiang University)Ministry of Education(No.2020P04)the support above is gratefully acknowledged.
文摘Freeze-sealing pipe roof method is applied in the Gongbei tunnel,which causes the ground surface uplift induced by frost heave.A frost heaving prediction approach based on the coefficient of cold expansion is proposed to simulate the ground deformation of the Gongbei tunnel.The coefficient of cold expansion in the model and the frost heaving rate from the frost heave test under the hydration condition can achieve a good correspondence making the calculation result closer to the actual engineering.The ground surface uplift along the lateral and longitudinal direction are respectively analyzed and compared with the field measured data to validate the model.The results show that a good agreement between the frost heaving prediction model and the field measured data verifies the rationality and applicability of the proposed model.The maximum uplift of the Gongbei tunnel appears at the center of the model,gradually decreasing along with the lateral and longitudinal directions.The curve in the lateral direction presents a normal distribution due to the influence of the constraint of two sides,while the one along the lateral direction shapes like a parabola with the opening downward due to the temperature field distribution.The model provides a reference for frost heaving engineering calculation.
基金supported by the National Natural Science Foundation of China(31201168)the Basic Research Program of Shanxi Province,China(20210302123411)the earmarked fund for Modern Agro-industry Technology Research System,China(2022-07).
文摘Determining the suitable areas for winter wheat under climate change and assessing the risk of freezing injury are crucial for the cultivation of winter wheat.We used an optimized Maximum Entropy(MaxEnt)Model to predict the potential distribution of winter wheat in the current period(1970-2020)and the future period(2021-2100)under four shared socioeconomic pathway scenarios(SSPs).We applied statistical downscaling methods to downscale future climate data,established a scientific and practical freezing injury index(FII)by considering the growth period of winter wheat,and analyzed the characteristics of abrupt changes in winter wheat freezing injury by using the Mann-Kendall(M-K)test.The results showed that the prediction accuracy AUC value of the MaxEnt Model reached 0.976.The minimum temperature in the coldest month,precipitation in the wettest season and annual precipitation were the main factors affecting the spatial distribution of winter wheat.The total suitable area of winter wheat was approximately 4.40×10^(7)ha in the current period.In the 2070s,the moderately suitable areas had the greatest increase by 9.02×10^(5)ha under SSP245 and the least increase by 6.53×10^(5)ha under SSP370.The centroid coordinates of the total suitable areas tended to move northward.The potential risks of freezing injury in the high-latitude and-altitude areas of the Loess Plateau,China increased significantly.The northern areas of Xinzhou in Shanxi Province,China suffered the most serious freezing injury,and the southern areas of the Loess Plateau suffered the least.Environmental factors such as temperature,precipitation and geographical location had important impacts on the suitable area distribution and freezing injury risk of winter wheat.In the future,greater attention should be paid to the northward boundaries of both the winter wheat planting areas and the areas of freezing injury risk to provide the early warning of freezing injury and implement corresponding management strategies.