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Coupling of the Calculated Freezing and Thawing Front Parameterization in the Earth System Model CAS-ESM 被引量:2
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作者 Ruichao LI Jinbo XIE +5 位作者 Zhenghui XIE Binghao JIA Junqiang GAO Peihua QIN Longhuan WANG Si CHEN 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2023年第9期1671-1688,共18页
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,hydro... 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. 展开更多
关键词 frozen ground freezing and thawing fronts maximum freezing depth active layer thickness earth system model CAS-ESM
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Artificial ground freezing of underground mines in cold regions using thermosyphons with air insulation
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作者 Ahmad F.Zueter Mohammad Zolfagharroshan +1 位作者 Navid Bahrani Agus P.Sasmito 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2024年第5期643-654,共12页
Current practice of underground artificial ground freezing(AGF)typically involves huge refrigeration systems of large economic and environmental costs.In this study,a novel AGF technique is proposed deploying availabl... Current practice of underground artificial ground freezing(AGF)typically involves huge refrigeration systems of large economic and environmental costs.In this study,a novel AGF technique is proposed deploying available cold wind in cold regions.This is achieved by a static heat transfer device called thermosyphon equipped with an air insulation layer.A refrigeration unit can be optionally integrated to meet additional cooling requirements.The introduction of air insulation isolates the thermosyphon from ground zones where freezing is not needed,resulting in:(1)steering the cooling resources(cold wind or refrigeration)towards zones of interest;and(2)minimizing refrigeration load.This design is demonstrated using well-validated mathematical models from our previous work based on two-phase enthalpy method of the ground coupled with a thermal resistance network for the thermosyphon.Two Canadian mines are considered:the Cigar Lake Mine and the Giant Mine.The results show that our proposed design can speed the freezing time by 30%at the Giant Mine and by two months at the Cigar Lake Mine.Further,a cooling load of 2.4 GWh can be saved at the Cigar Lake Mine.Overall,this study provides mining practitioners with sustainable solutions of underground AGF. 展开更多
关键词 Artificial ground freezing Underground mining Sustainable mining THERMOSYPHON Air insulation Cold regions
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Thermal performance of cast-in-place piles with artificial ground freezing in permafrost regions
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作者 WANG Xinbin CHEN Kun +3 位作者 YU Qihao GUO Lei YOU Yanhui JIN Mingyang 《Journal of Mountain Science》 SCIE CSCD 2024年第4期1307-1328,共22页
During the construction of cast-in-place piles in warm permafrost,the heat carried by concrete and the cement hydration reaction can cause strong thermal disturbance to the surrounding permafrost.Since the bearing cap... During the construction of cast-in-place piles in warm permafrost,the heat carried by concrete and the cement hydration reaction can cause strong thermal disturbance to the surrounding permafrost.Since the bearing capacity of the pile is quite small before the full freeze-back,the quick refreezing of the native soils surrounding the cast-in-place pile has become the focus of the infrastructure construction in permafrost.To solve this problem,this paper innovatively puts forward the application of the artificial ground freezing(AGF)method at the end of the curing period of cast-in-place piles in permafrost.A field test on the AGF was conducted at the Beiluhe Observation and Research Station of Frozen Soil Engineering and Environment(34°51.2'N,92°56.4'E)in the Qinghai Tibet Plateau(QTP),and then a 3-D numerical model was established to investigate the thermal performance of piles using AGF under different engineering conditions.Additionally,the long-term thermal performance of piles after the completion of AGF under different conditions was estimated.Field experiment results demonstrate that AGF is an effective method to reduce the refreezing time of the soil surrounding the piles constructed in permafrost terrain,with the ability to reduce the pile-soil interface temperatures to below the natural ground temperature within 3 days.Numerical results further prove that AGF still has a good cooling effect even under unfavorable engineering conditions such as high pouring temperature,large pile diameter,and large pile length.Consequently,the application of this method is meaningful to save the subsequent latency time and solve the problem of thermal disturbance in pile construction in permafrost.The research results are highly relevant for the spread of AGF technology and the rapid building of pile foundations in permafrost. 展开更多
关键词 Permafrost engineering Cast-in-place pile Artificial ground freezing Thermal performance.
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Experimental Study on the Effect of Fine-Grained Soil Content on the Freezing Strength of Aeolian Sand-Cement Interface
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作者 Junhui Hu Honghuan Cui Zhishu Xie 《Journal of World Architecture》 2024年第2期43-48,共6页
In cold regions,understanding the freezing strength of the interface between soil and structure is crucial for designing frost-resistant foundations.To investigate how the content of cement powder in aeolian sand affe... In cold regions,understanding the freezing strength of the interface between soil and structure is crucial for designing frost-resistant foundations.To investigate how the content of cement powder in aeolian sand affects this strength,we conducted direct shear tests under various conditions such as different fine-grained soil content,normal stress,and initial moisture content of the soil.By analyzing parameters like soil properties,and volume of ice content,and using the Mohr-Coulomb strength theory to define interface strength,we aimed to indirectly measure the cementation strength of the interface.Our findings revealed that as the particle content increased,the interface stress-strain curves became noticeably stiffer.We also observed a positive linear relationship between freezing strength and silt content,while the initial moisture content of the soil did not significantly impact the strengthening effect of fine-grained soil on freezing strength.Moreover,we discovered that as the powder content increased,the force binding the ice to the interface decreased,while the friction angle at the interface increased.However,the cohesion force at the interface remained relatively unchanged.Overall,our analysis suggests that the increase in freezing strength due to fine-grained soil content is primarily due to the heightened friction between aeolian sand and the interface. 展开更多
关键词 Fine-grained soil content Contact area freezing strength Influencing factors
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Exploring the Need and Strategy for Intraoperative Freezing to Identify Metastatic Adenocarcinoma of the Lungs
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作者 Yuemian Liang Ruiyao Wang 《Proceedings of Anticancer Research》 2024年第3期18-24,共7页
Objective: To explore the necessity and strategy of intraoperative freezing to identify primary and metastatic adenocarcinoma of the lung. Methods: This study retrospectively analyzes the impact of failing to make a d... Objective: To explore the necessity and strategy of intraoperative freezing to identify primary and metastatic adenocarcinoma of the lung. Methods: This study retrospectively analyzes the impact of failing to make a definitive diagnosis of metastatic adenocarcinoma of the lung on the clinical surgical approach in four cases of intraoperative freezing. It also examines the reasons for this failure and reviews the relevant literature. Results: All 4 cases of intraoperative freezing were diagnosed as invasive adenocarcinoma, and none of them made a definitive diagnosis of metastatic adenocarcinoma. Conclusion: It is difficult to confirm the diagnosis of metastatic adenocarcinoma of the lung by intraoperative frozen section, and the combination of patient history, rapid immunohistochemistry, and histological morphology of intraoperative frozen section for its identification can guide the surgeon to adjust the surgical approach in time and provide evidence for the establishment of surgical protocols for reference. 展开更多
关键词 Lung tumor Metastatic adenocarcinoma Intraoperative freezing
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Effects of freezing intensity on soil solution nitrogen and microbial biomass nitrogen in an alpine grassland ecosystem on the Tibetan Plateau,China 被引量:6
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作者 YANG Zhaoping GAO Jixi +1 位作者 YANG Meng SUN Zhizhong 《Journal of Arid Land》 SCIE CSCD 2016年第5期749-759,共11页
The change of freeze-thaw pattern of the Tibetan Plateau under climate warming is bound to have a profound impact on the soil process of alpine grassland ecosystem;however,the research on the impact of the freeze-thaw... The change of freeze-thaw pattern of the Tibetan Plateau under climate warming is bound to have a profound impact on the soil process of alpine grassland ecosystem;however,the research on the impact of the freeze-thaw action on nitrogen processes of the alpine grassland ecosystem on the Tibetan Plateau has not yet attracted much attention.In this study,the impact of the freezing strength on the soil nitrogen components of alpine grassland on the Tibetan Plateau was studied through laboratory freeze-thaw simulation experiments.The 0–10 cm topsoil was collected from the alpine marsh meadow and alpine meadow in the permafrost region of Beilu River.In the experiment,the soil samples were cultivated at –10℃,–7℃,–5℃,–3℃ and –1℃,respectively for three days and then thawed at 2℃ for one day.The results showed that after the freeze-thaw process,the soil microbial biomass nitrogen significantly decreased while the dissolved organic nitrogen and inorganic nitrogen significantly increased.When the freezing temperature was below –7℃,there was no significant difference between the content of nitrogen components,which implied a change of each nitrogen component might have a response threshold toward the freezing temperature.As the freeze-thaw process can lead to the risk of nitrogen loss in the alpine grassland ecosystem,more attention should be paid to the response of the soil nitrogen cycle of alpine grasslands on the Tibetan Plateau to the freeze-thaw process. 展开更多
关键词 freezing temperature microbial biomass nitrogen dissolved organic nitrogen inorganic nitrogen alpine grassland Tibetan Plateau
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The role of antioxidant system in freezing acclimation-induced freezing resistance of Populus suaveolens cuttings 被引量:1
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作者 Luo Lei Lin Shan-zhi Zheng Hui-quan Lei Yang Zhang Qian Zhang Zhi-yi 《Forestry Studies in China》 CAS 2007年第2期107-113,共7页
We investigated the changes in the contents of H202, malonaldehyde (MDA) and endogenous antioxidants, the activities of protective enzymes and some critical enzymes involved in the ascorbate-glutathione (ASA-GSH) ... We investigated the changes in the contents of H202, malonaldehyde (MDA) and endogenous antioxidants, the activities of protective enzymes and some critical enzymes involved in the ascorbate-glutathione (ASA-GSH) cycle as well as freezing resistance (expressed as LT50) and correlations mentioned above, in detail using Populus suaveolens cuttings. The purpose was to explore the physiological mechanism of the enhancement of freezing resistance induced by freezing acclimation at -20℃, and to elucidate the physiological mechanisms by which trees adapt to freezing. The results showed that freezing acclimation enhanced the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), monodehydroascorbate reductase (MDAR), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR) and glutathione reductase (GR). And it increased the contents of reduced ascorbate (ASA), reduced glutathione (GSH), dehydroascorbate (DHA) and oxidized glutathione (GSSG). However, H202 and MDA contents and LT50 of cuttings were decreased. LTs0 in cuttings was found to be closely correlated to the levels of SOD, POD, CAT, APX, DHAR, MDAR, GR, H202, MDA, ASA, GSH, DHA and GSSG during freezing acclimation. This suggested that the enhancement of freezing resistance of cuttings induced by freezing acclimation may relate to the distinct increase for the levels of SOD, POD, CAT, APX, DHAR, MDAR, GR, ASA, GSH, DHA, and GSSG. In addition, the observed levels of APX, DHAR, MDAR, GR, ASA, DHA, GSH and GSSG were higher than those of SOD, POD and CAT during freezing acclimation. It indicated that a higher capacity of the ASA-GSH cycle is required for H202 detoxification, and growth and development of cuttings. Based on the obtained results, it can be concluded that the ASA-GSH cycle plays an important role in enhancement of freezing resistance of P. suaveolens cuttings during freezing acclimation. 展开更多
关键词 Populus suaveolens freezing acclimation antioxidant system ASA-GSH cycle
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Response of Freezing/Thawing Indexes to the Wetting Trend under Warming Climate Conditions over the Qinghai–Tibetan Plateau during 1961–2010:A Numerical Simulation 被引量:2
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作者 Xuewei FANG Zhi LI +5 位作者 Chen CHENG Klaus FRAEDRICH Anqi WANG Yihui CHEN Yige XU Shihua LYU 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2023年第2期211-222,共12页
Since the 1990s,the Qinghai–Tibetan Plateau(QTP)has experienced a strikingly warming and wetter climate that alters the thermal and hydrological properties of frozen ground.A positive correlation between the warming ... Since the 1990s,the Qinghai–Tibetan Plateau(QTP)has experienced a strikingly warming and wetter climate that alters the thermal and hydrological properties of frozen ground.A positive correlation between the warming and thermal degradation in permafrost or seasonally frozen ground(SFG)has long been recognized.Still,a predictive relationship between historical wetting under warming climate conditions and frozen ground has not yet been well demonstrated,despite the expectation that it will become even more important because precipitation over the QTP has been projected to increase continuously in the near future.This study investigates the response of the thermal regime to historical wetting in both permafrost and SFG areas and examines their relationships separately using the Community Land Surface Model version 4.5.Results show that wetting before the 1990s across the QTP mainly cooled the permafrost body in the arid and semiarid zones,with significant correlation coefficients of 0.60 and 0.48,respectively.Precipitation increased continually at the rate of 6.16 mm decade–1 in the arid zone after the 1990s but had a contrasting warming effect on permafrost through a significant shortening of the thawing duration within the active layer.However,diminished rainfall in the humid zone after the 1990s also significantly extended the thawing duration of SFG.The relationship between the ground thawing index and precipitation was significantly negatively correlated(−0.75).The dual effects of wetting on the thermal dynamics of the QTP are becoming critical because of the projected increases in future precipitation. 展开更多
关键词 freezing/thawing indexes numerical modeling wetting process frozen ground Qinghai–Tibetan Plateau
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Overexpression of galactinol synthase 1 from Solanum commersonii(ScGolS1) confers freezing tolerance in transgenic potato 被引量:1
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作者 Feiyan He Jianfei Xu +4 位作者 Yinqiao Jian Shaoguang Duan Jun Hu Liping Jin Guangcun Li 《Horticultural Plant Journal》 SCIE CAS CSCD 2023年第3期541-552,共12页
Potato(Solanum tuberosum L.) is the fourth largest food crop in the world. Low temperatures cause serious damage to potato plants every year, and freezing tolerance has become a hot spot in potato research. Galactinol... Potato(Solanum tuberosum L.) is the fourth largest food crop in the world. Low temperatures cause serious damage to potato plants every year, and freezing tolerance has become a hot spot in potato research. Galactinol synthase(GolS) is a key enzyme in the synthesis of raffinose family oligosaccharides(RFOs), and plays an important role in the response of plants to abiotic stress. In this study, the ScGolS1 gene from Solanum commersonii was cloned and introduced into the S. tuberosum cultivars 'Atlantic' and 'Desiree' via Agrobacterium-mediated transformation. Phenotyping assays showed that overexpression of ScGolS1 could significantly improve freezing tolerance in transgenic potato plants.Further physiological and biochemical experiments showed that the transgenic lines had lower relative conductivity, malondialdehyde content,and 3,3-diaminobenzidine staining and a higher plant survival rate compared with wild type(WT) under cold stress. Moreover, the C-repeat binding factors(CBF1, CBF2 and CBF3), the downstream cold-responsive genes COR413 and COR47, and the ethylene-responsive factor(ERF)transcription factor genes ERF3, ERF4 and ERF6, which function in the ethylene signaling pathway, were all induced by freezing treatment and expressed at higher levels in the ScGolS1 overexpression lines compared with WT. Besides, the expression of some genes such as MIPS, STS and RS from the RFO metabolic pathway was up-regulated under cold stress, resulting in changes in the content of some soluble sugars. This indicated that ScGolS1 overexpression altered the sugar composition and enhanced freezing tolerance in transgenic potato by inducing the ethylene and CBF signaling pathways. These results provided theoretical support and genetic resources for freezing tolerance breeding in potato. 展开更多
关键词 Solanum commersonii ScGolS1 freezing tolerance RFOs ERF CBF
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Evaluation of freezing state of sandstone using ultrasonic time-frequency characteristics
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作者 Jiwei Zhang Julian Murton +4 位作者 Tim Cane Vikram Maji Lili Sui Shujie Liu Song Zhang 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2023年第3期584-599,共16页
Common problems in engineering projects that involve artificial ground freezing of soil or rock include inadequate thickness,strength and continuity of artificial frozen walls.It is difficult to evaluate the freezing ... Common problems in engineering projects that involve artificial ground freezing of soil or rock include inadequate thickness,strength and continuity of artificial frozen walls.It is difficult to evaluate the freezing state using only a few thermometer holes at fixed positions or with other existing approaches.Here we report a novel experimental design that investigates changes in ultrasonic properties(received waveform,wave velocity V_(p),wave amplitude,frequency spectrum,centroid frequency f_(c),kurtosis of the frequency spectrum KFS,and quality factor Q)measured during upward freezing,compared with those during uniform freezing,in order to determine the freezing state in 150 mm cubic blocks of Ardingly sandstone.Water content,porosity and density were estimated during upward freezing to ascertain water migration and changes of porosity and density at different stages.The period of receiving the wave increased substantially and coda waves changed from loose to compact during both upward and uniform freezing.The trend of increasing V_(p) can be divided into three stages during uniform freezing.During upward freezing,V_(p) increased more or less uniformly.The frequency spectrum could be used as a convenient and rapid method to identify different freezing states of sandstone(unfrozen,upward frozen,and uniformly frozen).The continuous changes in reflection coefficient r_(φ),refraction coefficient t_(φ) and acoustic impedance field are the major reason for larger reflection and refraction during upward freezing compared with uniform freezing.Wave velocity V_(p),wave amplitude A_(h),centroid frequency f_(c) and quality factor Q were adopted as ultrasonic parameters to evaluate quantitatively the temperature T of uniformly frozen sandstone,and their application within a radar chart is recommended.Determination of V_(p) provides a convenient method to evaluate the freezing state and calculate the cryofront height and frozen section thickness of upward frozen sandstone,with accuracies of 73.37%-99.23%. 展开更多
关键词 Frozen sandstone Uniform freezing Upward freezing Ultrasonic testing freezing state
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Variability of Raindrop Size Distribution during a Regional Freezing Rain Event in the Jianghan Plain of Central China
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作者 Jingjing LÜ Yue ZHOU +5 位作者 Zhikang FU Chunsong LU Qin HUANG Jing SUN Yue ZHAO Shengjie NIU 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2023年第4期725-742,I0015-I0018,共22页
The characteristics of the raindrop size distribution(DSD)during regional freezing rain(FR)events that occur throughout the phase change(from liquid to solid)are poorly understood due to limited observations.We invest... The characteristics of the raindrop size distribution(DSD)during regional freezing rain(FR)events that occur throughout the phase change(from liquid to solid)are poorly understood due to limited observations.We investigate the evolution of microphysical parameters and the key formation mechanisms of regional FR using the DSDs from five disdrometer sites in January 2018 in the Jianghan Plain(JHP)of Central China.FR is identified via the size and velocity distribution measured from a disdrometer,the discrete Fréchet distancemethod,surface temperature,human observations,and sounding data.With the persistence of precipitation,the emergence of graupel or snowflakes significantly reduces the proportion of FR.The enhancement of this regional FR event is mainly dominated by the increase in the number concentration of raindrops but weakly affected by the diameters.To improve the accuracy of quantitative precipitation estimation for the FR event,a modified second-degree polynomial relation between the shapeμand slopeΛof gamma DSDs is derived,and a new Z-R(radar reflectivity to rain rate)relationship is developed.The mean values of mass-weighted mean diameters(D_(m))and generalized intercepts(lgN_(w))in FR are close to the stratiform results in the northern region of China.Both the melting of tiny-rimed graupels and large-dry snowflakes are a response to the formation of this regional FR process in the JHP,dominated by the joint influence of the physical mechanism of warm rain,vapor deposition,and aggregation/riming coupled with the effect of weak convective motion in some periods. 展开更多
关键词 freezing rain raindrop size distribution hydrometeor type classification microphysical characteristics lgNw-Dm distribution Jianghan Plain
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New semi-analytical approach for ice lens heaving during artificial freezing of fine-grained material
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作者 K.Niggemann R.Fuentes 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2023年第11期2994-3009,共16页
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
关键词 Semi-analytical approach Ice lens formation Frost heaving Bottom freezing Segregation potential Frost-susceptible soil
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Protease inhibitor ASP enhances freezing tolerance by inhibiting protein degradation in kumquat
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作者 Hua Yang Ke-wei Qiao +5 位作者 Jin-jing Teng Jia-bei Chen Ying-li Zhong Li-qun Rao Xing-yao Xiong Huang Li 《Horticulture Research》 SCIE CSCD 2023年第4期53-62,共10页
Cold acclimation is a complex biological process leading to the development of freezing tolerance in plants.In this study,we demonstrated that cold-induced expression of protease inhibitor FmASP in a Citrus-relative s... Cold acclimation is a complex biological process leading to the development of freezing tolerance in plants.In this study,we demonstrated that cold-induced expression of protease inhibitor FmASP in a Citrus-relative species kumquat[Fortunella margarita(Lour.)Swingle]contributes to its freezing tolerance by minimizing protein degradation.Firstly,we found that only cold-acclimated kumquat plants,despite extensive leaf cellular damage during freezing,were able to resume their normal growth upon stress relief.To dissect the impact of cold acclimation on this anti-freezing performance,we conducted protein abundance assays and quantitative proteomic analysis of kumquat leaves subjected to cold acclimation(4◦C),freezing treatment(−10◦C)and post-freezing recovery(25◦C).FmASP(Against Serine Protease)and several non-specific proteases were identified as differentially expressed proteins induced by cold acclimation and associated with stable protein abundance throughout the course of low-temperature treatment.FmASP was further characterized as a robust inhibitor of multiple proteases.In addition,heterogeneous expression of FmASP in Arabidopsis confirmed its positive role in freezing tolerance.Finally,we proposed a working model of FmASP and illustrated how this extracellular-localized protease inhibitor protects proteins from degradation,therebymaintaining essential cellular function for post-freezing recovery.These findings revealed the important role of protease inhibition in freezing response and provide insights on how this role may help develop new strategies to enhance plant freezing tolerance. 展开更多
关键词 freezing INHIBITING thereby
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Design and Data Analysis of a New Type of Antifreezing Cup-Type Wind Velocity Sensor
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作者 Jiajia Zhang Jianguang Han +2 位作者 Jianan Yin Zheng Liu Ting Ma 《World Journal of Engineering and Technology》 2023年第4期672-681,共10页
In most areas of China, affected by the environment of low temperature and high humidity, the wind speed sensor and wind direction sensor are frozen and cannot output data in autumn, winter or the alternation of winte... In most areas of China, affected by the environment of low temperature and high humidity, the wind speed sensor and wind direction sensor are frozen and cannot output data in autumn, winter or the alternation of winter and spring. In order to solve the freezing situation of the wind sensor, this paper designs a new type of antifreeze wind speed sensor. After meteorology performance testing and field observation tests, the correlation coefficient of the observation data is demonstrated, and the data curve is fitted. The result shows the sensor is stable, and has a good antifreeze effect, the data output is reliable. 展开更多
关键词 Automatic Weather Station Wind Speed Sensor Wind Direction Sensor Freeze Cold-Resistant Technology
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A study on impacts of groundwater seepage on artificial freezing process of gravel strata
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作者 Tianliang Wang Ya-Meng He +1 位作者 Zhen Wu Jun-jun Li 《Railway Sciences》 2023年第1期1-12,共12页
Purpose–This paper aims to study the impacts of groundwater seepage on artificial freezing process of gravel strata,the temperature field characteristics of the strata,and the strata process,closure time and thicknes... Purpose–This paper aims to study the impacts of groundwater seepage on artificial freezing process of gravel strata,the temperature field characteristics of the strata,and the strata process,closure time and thickness evolution mechanism of the frozen wall.Design/methodology/approach–In this paper several laboratory model tests were conducted,considering different groundwater seepage rate.Findings–The results show that there is a significant coupling effect between the cold diffusion of artificial freezing pipes and groundwater seepage;when there is no seepage,temperature fields upstream and downstream of the gravel strata are symmetrically distributed,and the thickness of the frozen soil column/frozen wall is consistent during artificial freezing;groundwater seepage causes significant asymmetry in the temperature fields upstream and downstream of the gravel strata,and the greater the seepage rate,the more obvious the asymmetry;the frozen wall closure time increases linearly with the increase in the groundwater seepage rate,and specifically,the time length under seepage rate of 5.00 m d1 is 3.2 times longer than that under no seepage;due to the erosion from groundwater seepage,the thickness of the upstream frozen wall decreases linearly with the seepage velocity,while that of the downstream frozen wall increases linearly,resulting in a saddle-shaped frozen wall.Originality/value–The research results are beneficial to the optimum design and risk control of artificial freezing process in gravel strata. 展开更多
关键词 Underground works Gravel strata Temperature field Groundwater seepage Artificial freezing Frozen wall
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Influence of artificial freezing onliquefaction characteristics of Nanjing sand
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作者 Jie Zhou Zeyao Li +1 位作者 Wanjun Tian Jiawei Sun 《Railway Sciences》 2023年第1期13-32,共20页
Purpose–This study purposes to study the influence of artificial freezing on the liquefaction characteristics of Nanjing sand,as well as its mechanism.Design/methodology/approach–was studied through dynamic triaxial... Purpose–This study purposes to study the influence of artificial freezing on the liquefaction characteristics of Nanjing sand,as well as its mechanism.Design/methodology/approach–was studied through dynamic triaxial tests by means of the GDS dynamic triaxial system on Nanjing sand extensively discovered in the middle and lower reaches of the Yangtze River under seismic load and metro train vibration load,respectively,and potential hazards of the two loads to the freezing construction of Nanjing sand were also identified in the tests.Findings–The results show that under both seismic load and metro train vibration load,freeze-thaw cycles will significantly reduce the stiffness and liquefaction resistance of Nanjing sand,especially in the first freezethaw cycle;the more freeze-thaw cycles,the worse structural behaviors of silty-fine sand,and the easier to liquefy;freeze-thaw cycles will increase the sensitivity of Nanjing sand’s dynamic pore pressure to dynamic load response;the lower the freezing temperature and the effective confining pressure,the worse the liquefaction resistance of Nanjing sand after freeze-thaw cycles;compared to the metro train vibration load,the seismic load in Nanjing is potentially less dangerous to freezing construction of Nanjing sand.Originality/value–The research results are helpful to the construction of the artificial ground freezing of the subway crossing passage in the lower reaches of the Yangtze River and to ensure the construction safety of the subway tunnel and its crossing passage. 展开更多
关键词 METRO FOUNDATION Nanjing sand Artificial formation freezing method Sand liquefaction Dynamic triaxial test
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Strategies for Countering Freezing in Police Operational Activities
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作者 Franco Posa Jessica Leone +2 位作者 Francesco Sclavi Nicolas Poncini Christian Musso 《Journal of Sociology Study》 2023年第2期49-62,共14页
The term“freezing”refers to an innate defensive reaction characterized by the sudden cessation of all movements(Stote&Fanselow,2004;Eilam,2005).The freezing effect involving a police officer exposes him to a ris... The term“freezing”refers to an innate defensive reaction characterized by the sudden cessation of all movements(Stote&Fanselow,2004;Eilam,2005).The freezing effect involving a police officer exposes him to a risk to himself and others.Materials and Methods:400 anonymous questionnaires administered to law enforcement personnel in Switzerland were evaluated with the aim of testing their knowledge about the freezing phenomenon.In addition,semi-structured interviews involving police personnel were conducted.The authors also analyzed two cases of police officers who had experienced freezing.Results and Conclusions:From the results obtained,it emerges that freezing is not known to most of the police officers interviewed.Therefore,specific and innovative training seems to be necessary.The authors described the brain mechanisms that are involved in freezing.Innovative integrated training modules have been proposed by applying some neuroscientific knowledge,particularly using the potential of mirror neurons.The authors propose a strategy for supporting police officers who have experienced an episode of freezing.The ultimate goal is to provide more scientific tools to protect police officers and civilians. 展开更多
关键词 freezing POLICE SURVEY
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Frost heaving and crack initiation characteristics of tunnel rock mass in cold regions under low-temperature degradation
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作者 CHEN Wenhua XIANG Tian 《Journal of Mountain Science》 SCIE CSCD 2024年第8期2844-2854,共11页
Water freezing in rock fractures causes volumetric expansion and fracture development through frost heaving.This study introduces a novel analytical model to investigate how uneven freezing force and surrounding rock ... Water freezing in rock fractures causes volumetric expansion and fracture development through frost heaving.This study introduces a novel analytical model to investigate how uneven freezing force and surrounding rock pressure influence fracture initiation,based on mass conservation,elasticity,and water-ice phase transition principles.A model for rock fracture initiation considering freezing temperature,uneven freezing expansion,in-situ stress,and lateral pressure was proposed based on fracture mechanics.Equations for stress intensity factors were developed and validated using the phase field method.The effects of rock elastic modulus anisotropy and critical fracture energy density on fracture initiation were also discussed.The results show that the values of KI and KII exhibit an upward trend as the freezing temperature,uneven expansion,in-situ stress,and lateral pressure increase.The uneven freezing expansion has the most significant influence on KI and KII values among these parameters.As the uneven freezing expansion coefficient increases to 0.5,the fracture initiation mode shifts from tensile fracture to shear fracture.As the lateral pressure coefficient increases to 1,the fracture initiation mode shifts from tensile fracture to shear fracture.Rock elastic modulus anisotropy causes fractures to propagate in a clockwise direction,forming a'butterfly'pattern.Critical fracture energy density an isotropy causes counterclockwise deviation in propagation direction,resulting in branching paths and an'H'-shaped pattern. 展开更多
关键词 Rock fractures Fracture water Uneven freezing expansion Phase field method Initiation angle ANISOTROPY
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Macro-micro behaviors and failure mechanism of frozen weakly cemented mudstone
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作者 Xianzhou Lyu Jijie Du +2 位作者 Hao Fu Dawei Lyu Weiming Wang 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第4期1337-1347,共11页
Understanding the mechanical properties and multiscale failure mechanism of frozen soft rock is an important prerequisite for the construction safety of tunnels,artificially frozen ground and other infrastructure in c... Understanding the mechanical properties and multiscale failure mechanism of frozen soft rock is an important prerequisite for the construction safety of tunnels,artificially frozen ground and other infrastructure in cold regions.In this study,the triaxial compression test are performed on mudstone in the weakly cemented soft rock strata in the mining area of western China,and the mechanical characteristics and failure mechanism of weakly cemented mudstone are systematically investigated under the combined action of freezing and loading.Furthermore,the quantitative relationship between the microstructural parameters and the macroscopic strength and deformation parameters is established based on fractal theory.Thus,the failure mechanism of frozen weakly cemented mudstone is revealed on both micro- and macro-scales.The results show that temperature and confining pressure significantly affects the elastic modulus and peak strength of weakly cemented mudstone.With decreasing temperature,the compressive strength increases,while the corresponding peak strain decreases gradually.On the deformation curve,the plastic deformation stage is shortened,and the brittle fracture feature at the post-peak stage is more prominent,and the elastic modulus correspondingly increases with decreasing temperature.Under low-temperature conditions,most of the weakly cemented mudstone undergoes microscopic shear failure along the main fracture surface.The micro-fracture morphology characteristics of weakly cemented mudstone under different temperatures are quantified via the fractal dimension,and an approximately exponential relationship can be obtained among the fractal dimension and the temperature,compressive strength and elastic modulus. 展开更多
关键词 Weakly cemented mudstone Artificial freezing Mechanical properties Linkage destruction mechanism Fractal dimension
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Quantification of the concrete freeze–thaw environment across the Qinghai–Tibet Plateau based on machine learning algorithms
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作者 QIN Yanhui MA Haoyuan +3 位作者 ZHANG Lele YIN Jinshuai ZHENG Xionghui LI Shuo 《Journal of Mountain Science》 SCIE CSCD 2024年第1期322-334,共13页
The reasonable quantification of the concrete freezing environment on the Qinghai–Tibet Plateau(QTP) is the primary issue in frost resistant concrete design, which is one of the challenges that the QTP engineering ma... The reasonable quantification of the concrete freezing environment on the Qinghai–Tibet Plateau(QTP) is the primary issue in frost resistant concrete design, which is one of the challenges that the QTP engineering managers should take into account. In this paper, we propose a more realistic method to calculate the number of concrete freeze–thaw cycles(NFTCs) on the QTP. The calculated results show that the NFTCs increase as the altitude of the meteorological station increases with the average NFTCs being 208.7. Four machine learning methods, i.e., the random forest(RF) model, generalized boosting method(GBM), generalized linear model(GLM), and generalized additive model(GAM), are used to fit the NFTCs. The root mean square error(RMSE) values of the RF, GBM, GLM, and GAM are 32.3, 4.3, 247.9, and 161.3, respectively. The R^(2) values of the RF, GBM, GLM, and GAM are 0.93, 0.99, 0.48, and 0.66, respectively. The GBM method performs the best compared to the other three methods, which was shown by the results of RMSE and R^(2) values. The quantitative results from the GBM method indicate that the lowest, medium, and highest NFTC values are distributed in the northern, central, and southern parts of the QTP, respectively. The annual NFTCs in the QTP region are mainly concentrated at 160 and above, and the average NFTCs is 200 across the QTP. Our results can provide scientific guidance and a theoretical basis for the freezing resistance design of concrete in various projects on the QTP. 展开更多
关键词 Freeze–thaw cycles Quantification Machine learning algorithms Qinghai–Tibet Plateau CONCRETE
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