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
A novel vacuum ice slurry producing system with jet-pumps was proposed to deal with the problems of high energy consumption and ice blockage.In this novel system,one steam driven by a jet-pump was used to create vacuu...A novel vacuum ice slurry producing system with jet-pumps was proposed to deal with the problems of high energy consumption and ice blockage.In this novel system,one steam driven by a jet-pump was used to create vacuum in a hermetic vessel where water was sprayed through a nozzle to produce ice slurry,while the other steam was used to provide enough cold energy to make the left vapor in the hermetic vessel condense.Mathematical models of this novel system were established and theoretical simulation on the performance characteristics was also implemented based on the MATLAB program.Results show that the novel system is feasible and practicable,and the system performance is affected by many factors,such as the temperature of the generators,condensing temperature,evaporation temperature,and the cooling load of the refrigerator sub-system.The findings are helpful to improve the performance of ice slurry producing system.展开更多
Winter wheat （Triticum aestivum） cultivars Dongnongdongmai 1 with strong cold/freezing tolerance and Jimai 22 with weak cold/freezing tolerance were used for investigating the difference of microstructure and ultras...Winter wheat （Triticum aestivum） cultivars Dongnongdongmai 1 with strong cold/freezing tolerance and Jimai 22 with weak cold/freezing tolerance were used for investigating the difference of microstructure and ultrastructure between leaves of two cultivars under low temperature stress （5℃ and -15 ℃） using optical and electron microscope. The results showed that there was no obvious difference between leaves of Dongnongdongmai 1 and Jimai 22 in microstructure. However, the difference between those leaves was distinct in ultrastructure. The grana lamella and stroma lamella were stacked regularly and arranged parallelly along the long axis of chloroplasts in cv. Dongnongdongmai 1, while the arrangement directions of thylakoids in Jimai 22＇s leaves were so irregular as to form various angles with the long axis of chloroplasts. At -15℃, the mitochondrias were swelled to be round and the structure of cristaes became blurry in both cultivars＇ leaves, while some cristaes of Jimai 22 disappeared. These results would provide theoretical evidence for selecting cold/freezing tolerant winter wheat germplasm resources展开更多
A two-dimensional model for freezing and thawing phase change heat transfer in biological tissue embedded with two cryoprobes was established.In this model,the blood vessels were considered as tree-like branched fract...A two-dimensional model for freezing and thawing phase change heat transfer in biological tissue embedded with two cryoprobes was established.In this model,the blood vessels were considered as tree-like branched fractal network,and the effective flow rate and effective thermal conductivity of blood were obtained by fractal method.The temperature distribution and ice crystal growth process in biological tissue embedded with two cryoprobes during freezing-thawing process were numerically simulated.The results show that the growth velocity of ice crystal in freezing process from 200 to 400 s is more rapid than that from 400 to 600 s. Thawing process of frozen tissue occurs in the regions around cryoprobes tips and tissue boundary simultaneously,and the phase interfaces are close to each other until ice crystal melts completely.The distance of two cryoprobes has a more profound effect on the temperature distribution in freezing process at 400 s than at 800 s.展开更多
As one of the major projects of GAME (GEWEX Asian Monsoon Experiment), the GAME\|Tibet aimed to mainly examine the energy and water cycle in Tibetan Plateau and its effects on Asian monsoon. In this paper, based on th...As one of the major projects of GAME (GEWEX Asian Monsoon Experiment), the GAME\|Tibet aimed to mainly examine the energy and water cycle in Tibetan Plateau and its effects on Asian monsoon. In this paper, based on the in\|situ high\|resolution observation data of GAME\|Tibet, the soil energy\|moisture distribution and the melting\|freezing progresses and their effects on seasonal shift were preliminarily discussed.The soil energy\|water distribution and freezing\|melting processes varied at different sites in northern part of Tibetan Plateau. The temporal and spatial variation of the soil moisture content is more complex than that of temperature. The soil moisture content increased with depth in certain layers but decreased in other layers. The freezing and melting processes and the temperature distribution were largely influenced by the existence of higher soil moisture content layer. During summer monsoon, the soil moisture at 10cm at all sites is relatively high, but the spatial difference existed. Generally speaking, the shallow layers start to freeze in October and to melt from April at all sites, with about 6 months frozen period. However, the beginning time of freezing\|melting and frozen period varied at different sites.展开更多
In order to prolong semen preservation and improve pregnancy rate, semen freezing was studied with German shepherd dogs for experimental animals. The semen of four dogs was collected 40 times in four dilution frozen i...In order to prolong semen preservation and improve pregnancy rate, semen freezing was studied with German shepherd dogs for experimental animals. The semen of four dogs was collected 40 times in four dilution frozen into two formulations, according to the sperm motility to compare the advantages and disadvantages. The result indicated that the sperm motility of the pellet frozen semen in dilute 2 was significantly higher than that in dilution 1, 3, and 4 （P0.01）. The sperm motility of dogs semen with fried smoked method was notablely higher than that of frozen semen of program method （P0.01）. The dilution which contained yolk-Tris mainly was the best; the pellet semen frozen with fried smoked method was superior to tuble semen frozen with program freezing method; sperm motility of pellet semen was higher than that of tuble semen in the same dilution. The conception rate and litter size of the natural matting were higher than AI.展开更多
介绍了中国计量科学研究院新研制的两台高精度钠热管固定点炉(SHPF-1、SHPF-2),并测量了其垂直温场.当这两台钠热管固定点炉的炉温分别控制在比铝凝固点低约2℃、3℃时,铝点容器温度计阱底部150 mm范围内温场均匀性分别为15 mK和11 mK,...介绍了中国计量科学研究院新研制的两台高精度钠热管固定点炉(SHPF-1、SHPF-2),并测量了其垂直温场.当这两台钠热管固定点炉的炉温分别控制在比铝凝固点低约2℃、3℃时,铝点容器温度计阱底部150 mm范围内温场均匀性分别为15 mK和11 mK,并与国外同类的钠热管固定点炉的技术指标进行比较.此外,分析了影响固定点炉等温性能的因素.
Abstract：
Two sodium heat-pipe fixed point furnaces (SHPF-1, SHPF-2) developed at the National Institute of Metrology (NIM) are described, and their vertical temperature uniformities are measured. When the temperatures of the these two furnaces are controlled about 2 ℃ and 3 ℃ respectively, below the freezing point of the aluminum, the largest temperature differences did not exceed 15 mK and 11 mK in a distance about 150mm along the reentrant well of the aluminum point cell, respectively. These temperature uniformities are compared with those of foreign similar sodium heat pipe furnaces. Additionally, factors influencing isothermal characteristics of fixed point furnaces are analyzed.展开更多
Main meat freezing theories, including transition theory, glass transformation theory and ice crystallization theory, were introduced. Some novel freezing technologies such as high pressure freezing, ultrasonic freezi...Main meat freezing theories, including transition theory, glass transformation theory and ice crystallization theory, were introduced. Some novel freezing technologies such as high pressure freezing, ultrasonic freezing, ice nucleus bacteria freezing protein, cell alive system freezing and decompression freezing were also generally reviewed.展开更多
目的探讨智能冠状动脉运动追踪平台Snapshot Freeze（SSF）在冠状动脉CT血管成像（CCTA）中的应用价值。方法连续选取61例患者,使用Discovery CT750 HD Freedom进行冠状动脉扫描,扫描后分别使用和不使用SSF重建,得到A、B两组图像;根据...目的探讨智能冠状动脉运动追踪平台Snapshot Freeze（SSF）在冠状动脉CT血管成像（CCTA）中的应用价值。方法连续选取61例患者,使用Discovery CT750 HD Freedom进行冠状动脉扫描,扫描后分别使用和不使用SSF重建,得到A、B两组图像;根据扫描实时心率将患者分为低心率组（心率≤70次/分,n=34）,中高心率组（心率71～80次/分,n=14）和高心率组（心率〉80次/分,n=13）。对比分析A、B组间和不同心率组间的图像质量差异。结果除左主干（S5）外,B组冠状动脉各节段图像质量评分均优于A组（P均〈0.05）;S5段剔除评分为5分者后,其余7例B组图像质量均优于A组（P=0.008）;未使用SSF重建时不可诊断的42个节段经用SSF重建后全部可用于诊断。未使用SSF重建的不同心率组间除S7、S9段外,其余各节段图像质量评分差异均有统计学意义（P均〈0.05）,图像质量随心率增加而下降;使用SSF重建后,不同心率组间各节段图像质量评分差异均无统计学意义（P均〉0.05）。未使用SSF重建的右冠状动脉中段（S2）在15段中评分最低（2.88±0.91）分,S3次之（3.65±1.32）分,且S2在低心率组亦有17例出现移动伪影影响其评估;使用SSF重建后,S2、S3移动伪影显著改善,评分分别提升至（4.32±0.59）分和（4.49±0.59）分,均满足诊断需求。结论 SSF能够有效地纠正高心率及心率波动导致的冠状动脉血管移动伪影,优化CCTA图像质量,尤其对右冠状动脉移动伪影有显著意义。展开更多
Polyvinyl alcohol(PVA) physiological saline gel was prepared using physiological saline solution of the polymer by freezing and thawing method. The influences of the concentration of PVA, freezing and thawing cycle ti...Polyvinyl alcohol(PVA) physiological saline gel was prepared using physiological saline solution of the polymer by freezing and thawing method. The influences of the concentration of PVA, freezing and thawing cycle times and solvent swelling media on the swelling properties of PVA saline gel were investigated. The result show that the electrolytical ions have great effect on the swelling behavior of PVA saline gel. The equilibrium swelling ratio of PVA saline gel in aqueous swelling media is larger than that in saline swelling media. Also, the equilibrium swelling ratios of PVA saline gel in aqueous and in saline media decrease with the increase of gel concentration and the increase of freezing and thawing cycle times. The decreasing speed of equilibrium swelling ratio with the increase of freezing and thawing cycle times of PVA gel in distilled water is faster than that in physiological saline. The swelling kinetic equation can sufficiently describe the swelling behavior of PVA physiological saline gel.展开更多
The Heibei highway in expansion project is located in Xiaoxing’anling permafrost areas.Its total length is 148 km,and has 17 island permafrost sections.Some sugared above area exists uneven subsidence,which affects r...The Heibei highway in expansion project is located in Xiaoxing’anling permafrost areas.Its total length is 148 km,and has 17 island permafrost sections.Some sugared above area exists uneven subsidence,which affects road life and the stability of roadbed largely. The main reason for this is seasonal freezing and thawing of soil,resulting in the changes of foundation bearing capacity,and then the roadbed instability.In addition,many weak layers in the sugared area展开更多
02001 On the Realization of Intemational PracticalTemperature Scale of 1968 from 0℃ to 630 ℃.Pan Ruwen: 1 (1). 1980. pp.27--35.In present paper the apparatus and techniques used
Objective Visual cues(VC)are one of the most promising rehabilitative strategies for alleviating the PD patient’s freezing of gait.However,the mechanisms of turning’s neural control and its changes with VC are uncle...Objective Visual cues(VC)are one of the most promising rehabilitative strategies for alleviating the PD patient’s freezing of gait.However,the mechanisms of turning’s neural control and its changes with VC are unclear.This study investigates the neural control of muscle synergy during turning and its changes while using VC.展开更多
Freezing stress presents a severe threat for winter wheat(Triticum aestivum L.)during overwintering.Dehydration plays a significant role in plant cold-hardiness.In this study,dehydration-related traits were investigat...Freezing stress presents a severe threat for winter wheat(Triticum aestivum L.)during overwintering.Dehydration plays a significant role in plant cold-hardiness.In this study,dehydration-related traits were investigated between highly and tender freezing-tolerant winter wheat cultivars during the overwintering period.Accompanied by a decrease in temperature,the water content in crowns of highly freezing-tolerant winter wheat was significantly lower compared to that of tender freezing-tolerant winter wheat(control).The ratio of free and bound water content had slight changes in highly freezing-tolerant winter wheat,though there were wide fluctuations in the control.The transcript levels of dehydration-related genes were more expressed in the highly freezing-tolerant winter wheat than those in the control under freezing stress.The plant growth also showed significant differences between the two winter wheat cultivars.Based on these results,the study proposed that the highly freezing-tolerant winter wheat produces higher expression of dehydrins under freezing stress,causing additional dehydration in the tissue to avoid cell death caused by the formation of ice crystals.Furthermore,winter hardy cultivar also reduced the percentage of free water content that inhibited plant growth,and regulated the water composition for plant survival under freezing stress.展开更多
Although the dynamic properties of subgrade soils in seasonally frozen areas have already been studied, few researchers have considered the influence of shallow groundwater during the freeze–thaw(F–T) cycles. So a m...Although the dynamic properties of subgrade soils in seasonally frozen areas have already been studied, few researchers have considered the influence of shallow groundwater during the freeze–thaw(F–T) cycles. So a multifunctional F–T cycle system was developed to imitate the groundwater recharge in the subgrade during the freezing process and a large number of dynamic triaxial experiments were conducted after the F–T cycles. Some significant factors including the F–T cycle number, compaction degree, confining pressure, cyclic deviator stress, loading frequency, and water content were investigated for the resilient modulus of soils. The experimental results indicated that the dynamic resilient modulus of the subgrade was negatively correlated with the cyclic deviator stress, F–T cycle number, and initial water content, whereas the degree of compaction, confining pressure, and loading frequency could enhance the resilient modulus. Furthermore, a modified model considering the F–T cycle number and stress state was established to predict the dynamic resilient modulus. The calculated results of this modified model were very close to the experimental results. Consequently, calculation of the resilient modulus for F–T cycles considering the dynamic load was appropriate. This study provides reference for research focusing on F–T cycles with groundwater supply and the dynamic resilient moduli of subgrade soils in seasonally frozen areas.展开更多
Combustion chamber modeling and simulation of the liquid propellant engine with kerosene as fuel and liquid oxygen as an oxidizer in the turbulent flow field are performed by CFD technique.The flow is modeled as Singl...Combustion chamber modeling and simulation of the liquid propellant engine with kerosene as fuel and liquid oxygen as an oxidizer in the turbulent flow field are performed by CFD technique.The flow is modeled as Single-phase in steady state and using RNG k-ε turbulence model.Simulation results are validated by experimental data of thrust,special impulse and combustion chamber pressure.By comparing t.^wo reaction models of finite rate chemistry and frozen model with experimental data,it is concluded that finite rate chemistry has acceptable results.The optimum value of equivalence ratio(oxidizer to fuel ratio)per reaction and operational parameters of the engine which maximize thrust and special impulse are determined.展开更多
In this study, the Single Factor Test（SFT） was used to optimize the pre-freezing conditions of L. plantarum KLDS1.0391（KLDS1.0391）. Further, the Freeze-Drying Protective Agents（FDPA） of KLDS1.0391 was optimized ...In this study, the Single Factor Test（SFT） was used to optimize the pre-freezing conditions of L. plantarum KLDS1.0391（KLDS1.0391）. Further, the Freeze-Drying Protective Agents（FDPA） of KLDS1.0391 was optimized by Response Surface Methodology（RSM）. The optimum pretreatment conditions were as the follows： initial concentration of KLDS1.0391 was 1011 CFU · m L-1 and KLDS1.0391 was pre-freezed at –80℃ for 8 h to achieve the survival rate of 46.21%. The main components of FDPA were skim milk, sucrose, sodium glutamate and Tween-80. And the influence of four factors on the survival rate of KLDS1.0391 in freeze-drying was in order as the follows： skim milk〉sucrose〉Tween-80〉sodium glutamate. The optimal FDPA composition was skim milk 11.3%, sucrose 9.8%, sodium glutamate 5.1% and Tween-80 0.2%. Under the above conditions, the survival rate of the cells was 82.98%. Comparing the predicted values, the relative error was 0.37% and the difference was not significant, which indicated that the established model could effectively reflect the actual protection of FDPA to KLDS1.0391.展开更多
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Project(51376198)supported by the National Natural Science Foundation of ChinaProject(11JJ22029)supported by the Hunan Provincial Natural Science Foundation of China
文摘A novel vacuum ice slurry producing system with jet-pumps was proposed to deal with the problems of high energy consumption and ice blockage.In this novel system,one steam driven by a jet-pump was used to create vacuum in a hermetic vessel where water was sprayed through a nozzle to produce ice slurry,while the other steam was used to provide enough cold energy to make the left vapor in the hermetic vessel condense.Mathematical models of this novel system were established and theoretical simulation on the performance characteristics was also implemented based on the MATLAB program.Results show that the novel system is feasible and practicable,and the system performance is affected by many factors,such as the temperature of the generators,condensing temperature,evaporation temperature,and the cooling load of the refrigerator sub-system.The findings are helpful to improve the performance of ice slurry producing system.
基金Supported by Doctoral Scientific Research Project of Northeast Agricultural University (20082010)Innovative Research Team Project of Northeast Agricultural University (CXZ003)
文摘Winter wheat （Triticum aestivum） cultivars Dongnongdongmai 1 with strong cold/freezing tolerance and Jimai 22 with weak cold/freezing tolerance were used for investigating the difference of microstructure and ultrastructure between leaves of two cultivars under low temperature stress （5℃ and -15 ℃） using optical and electron microscope. The results showed that there was no obvious difference between leaves of Dongnongdongmai 1 and Jimai 22 in microstructure. However, the difference between those leaves was distinct in ultrastructure. The grana lamella and stroma lamella were stacked regularly and arranged parallelly along the long axis of chloroplasts in cv. Dongnongdongmai 1, while the arrangement directions of thylakoids in Jimai 22＇s leaves were so irregular as to form various angles with the long axis of chloroplasts. At -15℃, the mitochondrias were swelled to be round and the structure of cristaes became blurry in both cultivars＇ leaves, while some cristaes of Jimai 22 disappeared. These results would provide theoretical evidence for selecting cold/freezing tolerant winter wheat germplasm resources
基金Project(50436030)supported by the National Natural Science Foundation of China
文摘A two-dimensional model for freezing and thawing phase change heat transfer in biological tissue embedded with two cryoprobes was established.In this model,the blood vessels were considered as tree-like branched fractal network,and the effective flow rate and effective thermal conductivity of blood were obtained by fractal method.The temperature distribution and ice crystal growth process in biological tissue embedded with two cryoprobes during freezing-thawing process were numerically simulated.The results show that the growth velocity of ice crystal in freezing process from 200 to 400 s is more rapid than that from 400 to 600 s. Thawing process of frozen tissue occurs in the regions around cryoprobes tips and tissue boundary simultaneously,and the phase interfaces are close to each other until ice crystal melts completely.The distance of two cryoprobes has a more profound effect on the temperature distribution in freezing process at 400 s than at 800 s.
文摘As one of the major projects of GAME (GEWEX Asian Monsoon Experiment), the GAME\|Tibet aimed to mainly examine the energy and water cycle in Tibetan Plateau and its effects on Asian monsoon. In this paper, based on the in\|situ high\|resolution observation data of GAME\|Tibet, the soil energy\|moisture distribution and the melting\|freezing progresses and their effects on seasonal shift were preliminarily discussed.The soil energy\|water distribution and freezing\|melting processes varied at different sites in northern part of Tibetan Plateau. The temporal and spatial variation of the soil moisture content is more complex than that of temperature. The soil moisture content increased with depth in certain layers but decreased in other layers. The freezing and melting processes and the temperature distribution were largely influenced by the existence of higher soil moisture content layer. During summer monsoon, the soil moisture at 10cm at all sites is relatively high, but the spatial difference existed. Generally speaking, the shallow layers start to freeze in October and to melt from April at all sites, with about 6 months frozen period. However, the beginning time of freezing\|melting and frozen period varied at different sites.
文摘In order to prolong semen preservation and improve pregnancy rate, semen freezing was studied with German shepherd dogs for experimental animals. The semen of four dogs was collected 40 times in four dilution frozen into two formulations, according to the sperm motility to compare the advantages and disadvantages. The result indicated that the sperm motility of the pellet frozen semen in dilute 2 was significantly higher than that in dilution 1, 3, and 4 （P0.01）. The sperm motility of dogs semen with fried smoked method was notablely higher than that of frozen semen of program method （P0.01）. The dilution which contained yolk-Tris mainly was the best; the pellet semen frozen with fried smoked method was superior to tuble semen frozen with program freezing method; sperm motility of pellet semen was higher than that of tuble semen in the same dilution. The conception rate and litter size of the natural matting were higher than AI.
文摘介绍了中国计量科学研究院新研制的两台高精度钠热管固定点炉(SHPF-1、SHPF-2),并测量了其垂直温场.当这两台钠热管固定点炉的炉温分别控制在比铝凝固点低约2℃、3℃时,铝点容器温度计阱底部150 mm范围内温场均匀性分别为15 mK和11 mK,并与国外同类的钠热管固定点炉的技术指标进行比较.此外,分析了影响固定点炉等温性能的因素.
Abstract：
Two sodium heat-pipe fixed point furnaces (SHPF-1, SHPF-2) developed at the National Institute of Metrology (NIM) are described, and their vertical temperature uniformities are measured. When the temperatures of the these two furnaces are controlled about 2 ℃ and 3 ℃ respectively, below the freezing point of the aluminum, the largest temperature differences did not exceed 15 mK and 11 mK in a distance about 150mm along the reentrant well of the aluminum point cell, respectively. These temperature uniformities are compared with those of foreign similar sodium heat pipe furnaces. Additionally, factors influencing isothermal characteristics of fixed point furnaces are analyzed.
文摘Main meat freezing theories, including transition theory, glass transformation theory and ice crystallization theory, were introduced. Some novel freezing technologies such as high pressure freezing, ultrasonic freezing, ice nucleus bacteria freezing protein, cell alive system freezing and decompression freezing were also generally reviewed.
文摘Polyvinyl alcohol(PVA) physiological saline gel was prepared using physiological saline solution of the polymer by freezing and thawing method. The influences of the concentration of PVA, freezing and thawing cycle times and solvent swelling media on the swelling properties of PVA saline gel were investigated. The result show that the electrolytical ions have great effect on the swelling behavior of PVA saline gel. The equilibrium swelling ratio of PVA saline gel in aqueous swelling media is larger than that in saline swelling media. Also, the equilibrium swelling ratios of PVA saline gel in aqueous and in saline media decrease with the increase of gel concentration and the increase of freezing and thawing cycle times. The decreasing speed of equilibrium swelling ratio with the increase of freezing and thawing cycle times of PVA gel in distilled water is faster than that in physiological saline. The swelling kinetic equation can sufficiently describe the swelling behavior of PVA physiological saline gel.
文摘The Heibei highway in expansion project is located in Xiaoxing’anling permafrost areas.Its total length is 148 km,and has 17 island permafrost sections.Some sugared above area exists uneven subsidence,which affects road life and the stability of roadbed largely. The main reason for this is seasonal freezing and thawing of soil,resulting in the changes of foundation bearing capacity,and then the roadbed instability.In addition,many weak layers in the sugared area
文摘02001 On the Realization of Intemational PracticalTemperature Scale of 1968 from 0℃ to 630 ℃.Pan Ruwen: 1 (1). 1980. pp.27--35.In present paper the apparatus and techniques used
基金National Nature Science Foundation of China,11972233
文摘Objective Visual cues(VC)are one of the most promising rehabilitative strategies for alleviating the PD patient’s freezing of gait.However,the mechanisms of turning’s neural control and its changes with VC are unclear.This study investigates the neural control of muscle synergy during turning and its changes while using VC.
基金Supported by Youth Innovation Talent Project of the General Undergraduate Universities in Heilongjiang Province(UNPYSCT-2018156)。
文摘Freezing stress presents a severe threat for winter wheat(Triticum aestivum L.)during overwintering.Dehydration plays a significant role in plant cold-hardiness.In this study,dehydration-related traits were investigated between highly and tender freezing-tolerant winter wheat cultivars during the overwintering period.Accompanied by a decrease in temperature,the water content in crowns of highly freezing-tolerant winter wheat was significantly lower compared to that of tender freezing-tolerant winter wheat(control).The ratio of free and bound water content had slight changes in highly freezing-tolerant winter wheat,though there were wide fluctuations in the control.The transcript levels of dehydration-related genes were more expressed in the highly freezing-tolerant winter wheat than those in the control under freezing stress.The plant growth also showed significant differences between the two winter wheat cultivars.Based on these results,the study proposed that the highly freezing-tolerant winter wheat produces higher expression of dehydrins under freezing stress,causing additional dehydration in the tissue to avoid cell death caused by the formation of ice crystals.Furthermore,winter hardy cultivar also reduced the percentage of free water content that inhibited plant growth,and regulated the water composition for plant survival under freezing stress.
基金Projects(41672312, 41972294) supported by the National Natural Science Foundation of ChinaProject(2017CFA056) supported by the Outstanding Youth Foundation of Hubei Province, ChinaProject(KFJ170104) supported by the Changsha University of Science & Technology via Open Fund of National Engineering Laboratory of Highway Maintenance Technology, China。
文摘Although the dynamic properties of subgrade soils in seasonally frozen areas have already been studied, few researchers have considered the influence of shallow groundwater during the freeze–thaw(F–T) cycles. So a multifunctional F–T cycle system was developed to imitate the groundwater recharge in the subgrade during the freezing process and a large number of dynamic triaxial experiments were conducted after the F–T cycles. Some significant factors including the F–T cycle number, compaction degree, confining pressure, cyclic deviator stress, loading frequency, and water content were investigated for the resilient modulus of soils. The experimental results indicated that the dynamic resilient modulus of the subgrade was negatively correlated with the cyclic deviator stress, F–T cycle number, and initial water content, whereas the degree of compaction, confining pressure, and loading frequency could enhance the resilient modulus. Furthermore, a modified model considering the F–T cycle number and stress state was established to predict the dynamic resilient modulus. The calculated results of this modified model were very close to the experimental results. Consequently, calculation of the resilient modulus for F–T cycles considering the dynamic load was appropriate. This study provides reference for research focusing on F–T cycles with groundwater supply and the dynamic resilient moduli of subgrade soils in seasonally frozen areas.
文摘Combustion chamber modeling and simulation of the liquid propellant engine with kerosene as fuel and liquid oxygen as an oxidizer in the turbulent flow field are performed by CFD technique.The flow is modeled as Single-phase in steady state and using RNG k-ε turbulence model.Simulation results are validated by experimental data of thrust,special impulse and combustion chamber pressure.By comparing t.^wo reaction models of finite rate chemistry and frozen model with experimental data,it is concluded that finite rate chemistry has acceptable results.The optimum value of equivalence ratio(oxidizer to fuel ratio)per reaction and operational parameters of the engine which maximize thrust and special impulse are determined.
基金Supported by the Outstanding Youth Scientists Foundation of Harbin City(2014RFYXJ006)
文摘In this study, the Single Factor Test（SFT） was used to optimize the pre-freezing conditions of L. plantarum KLDS1.0391（KLDS1.0391）. Further, the Freeze-Drying Protective Agents（FDPA） of KLDS1.0391 was optimized by Response Surface Methodology（RSM）. The optimum pretreatment conditions were as the follows： initial concentration of KLDS1.0391 was 1011 CFU · m L-1 and KLDS1.0391 was pre-freezed at –80℃ for 8 h to achieve the survival rate of 46.21%. The main components of FDPA were skim milk, sucrose, sodium glutamate and Tween-80. And the influence of four factors on the survival rate of KLDS1.0391 in freeze-drying was in order as the follows： skim milk〉sucrose〉Tween-80〉sodium glutamate. The optimal FDPA composition was skim milk 11.3%, sucrose 9.8%, sodium glutamate 5.1% and Tween-80 0.2%. Under the above conditions, the survival rate of the cells was 82.98%. Comparing the predicted values, the relative error was 0.37% and the difference was not significant, which indicated that the established model could effectively reflect the actual protection of FDPA to KLDS1.0391.
