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Tingjun Zhang - One of the best experts on this subject based on the ideXlab platform.
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observational study on the active layer freeze thaw Cycle in the upper reaches of the heihe river of the north eastern qinghai tibet plateau
Quaternary International, 2017Co-Authors: Qingfeng Wang, Xiaoqing Peng, Tingjun Zhang, Kang Wang, Lili LiAbstract:Abstract Observational data collection on permafrost and active layer freeze–thaw Cycle is extremely limited in the upper reaches of the Heihe River (URHHR) in the Qilian Mountains of the north-eastern Qinghai-Tibet Plateau. It acts as a bottleneck, restricting the hydrological effects of the changes in the permafrost and active layer in the Heihe River Basin. Using soil temperature, moisture and air temperature data collected from the four active layer observation sites (AL1, AL3, AL4 and AL7) established in the alpine permafrost regions in the URHHR, from 2013 to 2014, the region's active layer freeze–thaw Cycle and the soil hydrothermal dynamics were comparatively analysed. As the elevation increased from 3700 m a.s.l. to 4132 m a.s.l., the mean annual ground temperatures (MAGTs) of the active layer and the active layer thicknesses (ALTs) decreased, the onset date of soil freeze of the active layer occurred earlier and the soil freeze rate increased. However, the onset date of soil thaw and the thaw rate did not exhibit significant trends. Compared to the thaw process, the duration of the active layer freeze process was significantly shortened and its rate was significantly higher. The soil freeze from bottom to top did not occur earlier than that from top to bottom. Furthermore, as elevation increased, the proportion of the bottom-up freeze layer thickness increased. The soil moisture in the thaw layer continuously moved to the freeze front during the active layer's two-way freeze process, causing the thaw layer to be dewatered. The seasonal thaw process resulted in significant reduction of the soil water content in the thaw layer, accounting for the high ice content in the vicinity of the permafrost table. Controlled by elevation, the active layer's seasonal freeze–thaw Cycle was also affected by local factors, such as vegetation, slope, water (marsh water and super-permafrost water), lithology and water (ice) content. This study provides quantitative data that identify, simulate and predict the hydrological effects of the changes in the permafrost and active layer of the Heihe River Basin.
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changes in the near surface soil freeze thaw Cycle on the qinghai tibetan plateau
International Journal of Applied Earth Observation and Geoinformation, 2012Co-Authors: Xin Li, Tingjun ZhangAbstract:Abstract Changes in the near-surface soil freeze–thaw Cycle on the Qinghai-Tibetan Plateau (QTP) were detected using daily soil freeze/thaw states derived from Special Sensor Microwave/Imager data from 1988 to 2007. Linear trends in freeze and thaw dates, the number of total frozen days of each pixel, and the numbers of monthly and yearly frozen days averaged over the whole QTP were analyzed. Principal component analysis was used to investigate the spatial variation in the freeze–thaw Cycle. The results show that on the QTP there was a trend toward earlier onset date of soil thaw by approximately 14 days, and later onset date of soil freeze by approximately 10 days over the period 1988–2007. The number of frozen days has decreased over the QTP by 16.8 days per decade. This decrease in the number of frozen days has occurred mainly from April to September, with a more pronounced trend in warmer months. The most significant changes were in the northeastern and southwestern QTP, where discontinuous permafrost, island permafrost, and seasonally frozen ground are presented. The northwestern QTP had almost no change, where permafrost is cold and stable. The trend in the near-surface soil freeze–thaw Cycle is positively related with climate warming on the QTP. Much warmer winters may account for significantly earlier thawing, later freezing, and a substantial reduction in the number of frozen days on the QTP. These changes in the near-surface soil freeze–thaw Cycle can be used both as an effective indicator of the permafrost change and for mapping of permafrost stability. Changes in near-surface soil freeze–thaw Cycle and consequently permafrost conditions would have dramatic influence on hydrologic processes, ecosystem, and engineering operations over the QTP.
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investigation of the near surface soil freeze thaw Cycle in the contiguous united states algorithm development and validation
Journal of Geophysical Research, 2003Co-Authors: Tingjun Zhang, R L Armstrong, John A. SmithAbstract:[1] A combined frozen soil algorithm was developed and validated to detect the near-surface soil freeze/thaw Cycle over snow-free and snow-covered land areas in the contiguous United States. The combined frozen soil algorithm consists of two parts. (1) Over snow-free land areas, a passive microwave remote sensing algorithm was used to detect the near-surface soil freeze/thaw Cycle. (2) Over snow-covered land areas, a one-dimensional numerical heat transfer model with phase change was used to detect soil freeze/thaw status under snow cover. Using the Defense Meteorological Satellite Program's Special Sensor Microwave Imager (SSM/I) data, the passive microwave algorithm uses a negative spectral gradient between 19 and 37 GHz, vertically polarized brightness temperatures, and a cutoff brightness temperature at 37 GHz with vertical polarization (TB(37V)). SSM/I data and soil temperature data from 26 stations over the contiguous United States from 2 year period, 1 July 1997 through 30 June 1999, were used to calibrate the algorithm (year 1), to validate the algorithm (year 2), and to demonstrate freeze/thaw classification (both years). A cutoff brightness temperature of 258.2 K was obtained on the basis of a linear correlation (r2 = 0.84) between the soil temperature at 5 cm depth and the TB(37V). The combined frozen soil algorithm provides an accuracy for frozen soil detection of about 76% and an accuracy for the correct classification of both frozen and unfrozen soils of approximately 83% with a percent error of about 17%. The combined frozen soil algorithm was used to investigate the timing, duration and number of days, and daily area extent of near-surface frozen soils over the study area. The primary results indicate that the maximum area extent of frozen ground during the winter of 1997/1998 was about 4.4 × 106 km2 or 63% of the total land area of the contiguous United States, while during the winter of 1998/1999, the maximum extent was about 5.2 × 106 km2 or 74%. The duration of the soil freeze ranges from less than 1 month in the south to over 8 months in the Rocky Mountains. The actual number of days of soil freezing varies from a few weeks to more than several months. The number of near-surface soil freeze/thaw Cycles varied from 1 to more than 11 during the winters of 1997/1998 and 1998/1999, while the average length frozen period varied from less than 20 days to more than 220 days.
Hugh A L Henry - One of the best experts on this subject based on the ideXlab platform.
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Freeze–thaw Cycle amplitude and freezing rate effects on extractable nitrogen in a temperate old field soil
Biology and Fertility of Soils, 2009Co-Authors: Amy C Elliott, Hugh A L HenryAbstract:Freeze–thaw Cycles can promote soil N losses as a result of microbial and root cell lysis; however, minimal freeze–thaw effects have typically been observed in studies that have imposed moderate temperature Cycles. We conducted laboratory incubations on surface soil (top 3 cm) collected in a temperate old field from late fall through mid-winter to examine how variation in freeze–thaw amplitude, number, timing of collection, and freezing rate altered soil extractable N. We varied freeze–thaw amplitude by imposing minimum Cycle temperatures of 0, −1, −2, −5, and −10°C for a series of either one or two Cycles and held control samples constant at 3°C. We also examined the effects of freezing rates of 1, 3, and 30°C h^−1. We hypothesized that extractable N would be highest for both the maximum freezing amplitudes and rates. While multiple freeze–thaw Cycles at −10°C and freeze–thaw Cycles associated with artificially high freezing rates increased extractable N, freeze–thaw Cycles representative of field conditions at our site had no effect on extractable N in late fall and early winter. By mid-winter there was a significant freeze–thaw Cycle effect but, contrary to our prediction, less N was extracted from freeze–thaw treated samples than from the control samples, which remained thawed over the treatment period. Increased extractable N in control samples was driven by increased organic N rather than increased inorganic N. Our results suggest that freeze–thaw damage to soil organisms does not contribute substantially to N release in our system. Instead, soil extractable N may increase during mid-winter thaws as a result of increased soil proteolytic activity above freezing temperatures.
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freeze thaw Cycle amplitude and freezing rate effects on extractable nitrogen in a temperate old field soil
Biology and Fertility of Soils, 2009Co-Authors: Amy C Elliott, Hugh A L HenryAbstract:Freeze–thaw Cycles can promote soil N losses as a result of microbial and root cell lysis; however, minimal freeze–thaw effects have typically been observed in studies that have imposed moderate temperature Cycles. We conducted laboratory incubations on surface soil (top 3 cm) collected in a temperate old field from late fall through mid-winter to examine how variation in freeze–thaw amplitude, number, timing of collection, and freezing rate altered soil extractable N. We varied freeze–thaw amplitude by imposing minimum Cycle temperatures of 0, −1, −2, −5, and −10°C for a series of either one or two Cycles and held control samples constant at 3°C. We also examined the effects of freezing rates of 1, 3, and 30°C h−1. We hypothesized that extractable N would be highest for both the maximum freezing amplitudes and rates. While multiple freeze–thaw Cycles at −10°C and freeze–thaw Cycles associated with artificially high freezing rates increased extractable N, freeze–thaw Cycles representative of field conditions at our site had no effect on extractable N in late fall and early winter. By mid-winter there was a significant freeze–thaw Cycle effect but, contrary to our prediction, less N was extracted from freeze–thaw treated samples than from the control samples, which remained thawed over the treatment period. Increased extractable N in control samples was driven by increased organic N rather than increased inorganic N. Our results suggest that freeze–thaw damage to soil organisms does not contribute substantially to N release in our system. Instead, soil extractable N may increase during mid-winter thaws as a result of increased soil proteolytic activity above freezing temperatures.
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soil freeze thaw Cycle experiments trends methodological weaknesses and suggested improvements
Soil Biology & Biochemistry, 2007Co-Authors: Hugh A L HenryAbstract:Abstract Although freeze–thaw Cycles can alter soil physical properties and microbial activity, their overall impact on soil functioning remains unclear. This review addresses the effects of freeze–thaw Cycles on soil physical properties, microorganisms, carbon and nutrient dynamics, trace gas losses and higher organisms associated with soil. I discuss how the controlled manipulation of freeze–thaw Cycles has varied widely among studies and propose that, despite their value in demonstrating the mechanisms of freeze–thaw action in soils, many studies of soil freeze–thaw Cycles have used Cycle amplitudes, freezing rates and minimum temperatures that are not relevant to temperature changes across much of the soil profile in situ. The lack of coordination between the timing of soil collection and the season for which freeze–thaw Cycles are being simulated is also discussed. Suggested improvements to future studies of soil freeze–thaw Cycles include the maintenance of realistic temperature fluctuations across the soil profile, soil collection in the appropriate season and the inclusion of relevant surface factors such as plant litter in the fall or excess water in the spring. The implications of climate change for soil freeze–thaw Cycles are addressed, along with the need to directly assess how changes in soil freeze–thaw Cycle dynamics alter primary production.
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Soil freeze–thaw Cycle experiments: Trends, methodological weaknesses and suggested improvements
Soil Biology & Biochemistry, 2007Co-Authors: Hugh A L HenryAbstract:Abstract Although freeze–thaw Cycles can alter soil physical properties and microbial activity, their overall impact on soil functioning remains unclear. This review addresses the effects of freeze–thaw Cycles on soil physical properties, microorganisms, carbon and nutrient dynamics, trace gas losses and higher organisms associated with soil. I discuss how the controlled manipulation of freeze–thaw Cycles has varied widely among studies and propose that, despite their value in demonstrating the mechanisms of freeze–thaw action in soils, many studies of soil freeze–thaw Cycles have used Cycle amplitudes, freezing rates and minimum temperatures that are not relevant to temperature changes across much of the soil profile in situ. The lack of coordination between the timing of soil collection and the season for which freeze–thaw Cycles are being simulated is also discussed. Suggested improvements to future studies of soil freeze–thaw Cycles include the maintenance of realistic temperature fluctuations across the soil profile, soil collection in the appropriate season and the inclusion of relevant surface factors such as plant litter in the fall or excess water in the spring. The implications of climate change for soil freeze–thaw Cycles are addressed, along with the need to directly assess how changes in soil freeze–thaw Cycle dynamics alter primary production.
Y. Martin Lo - One of the best experts on this subject based on the ideXlab platform.
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Influence of Xanthan–Curdlan Hydrogel Complex on Freeze‐Thaw Stability and Rheological Properties of Whey Protein Isolate Gel over Multiple Freeze‐Thaw Cycle
Journal of Food Science, 2015Co-Authors: Setareh Ghorban Shiroodi, Barbara Rasco, Y. Martin LoAbstract:UNLABELLED: The effect of adding xanthan-curdlan hydrogel complex (XCHC) at 2 concentrations (0.25 and 0.5% w/w) on the Freeze-Thaw stability of heat-induced whey protein isolate (WPI) gel was investigated. Samples were stored at 4 °C for 24 h before subjected to 5 Freeze-Thaw Cycles alternating between -16 °C (18 h) and 25 °C (6 h). Adding XCHC to the WPI solution resulted in the reduction of a significant amount of syneresis up to 5 repeated Freeze-Thaw Cycles. Addition of XCHC decreased the amount of syneresis from 45% in the control sample (pure WPI gel) to 31.82% and 5.44% in the samples containing 0.25% and 0.5% gum, respectively, after the 5th Freeze-Thaw Cycle. XCHC increased the storage modulus (G') of the gels and minimized the changes of the G' values over the 5 Freeze-Thaw Cycles, indicating improvement of the stability of the system. Furthermore, the minimum protein concentration for gel formation decreased in the presence of the XCHC. Scanning electron microscopy (SEM) images showed that addition of XCHC resulted in the formation of a well-structured gel with numerous small pores in the network, which consequently improved the water retention ability during the temperature abuses up to 5 Freeze-Thaw Cycles. These results have important implications for using XCHC in the formulation of the frozen WPI-based products with improved Freeze-Thaw stability and rheological properties. PRACTICAL APPLICATION: Application of XCHC in the formulation of frozen dairy-based food products has the potential to enhance Freeze-Thaw stability and minimize moisture migration caused by temperature abuses of the products during distribution and consumer application.
Shunbo Zhao - One of the best experts on this subject based on the ideXlab platform.
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influences of freeze thaw Cycle and curing time on chloride ion penetration resistance of sulphoaluminate cement concrete
Construction and Building Materials, 2014Co-Authors: Jun Zhao, Shunbo ZhaoAbstract:Abstract In this paper, the influences of freeze–thaw Cycle and curing time on the chloride ion penetration resistance of Portland and Sulphoaluminate cement concretes were researched. Results show that freeze–thaw Cycle and curing time have significant influences on chloride ion penetration resistance of the two cement concretes. Although the chloride diffusion coefficients of the two cement concretes decrease gradually when curing time increases, it is much lower for Sulphoaluminate cement concrete. The chloride diffusion coefficient and chloride ion penetration depth both increase obviously after the two cement concretes were subjected to the freeze–thaw Cycles, which indicates that the freeze–thaw Cycles can accelerate the chloride ion diffusion into the two concretes. Under the same freeze–thaw Cycle and curing time, Sulphoaluminate cement concrete has much better chloride ion penetration resistance than Portland cement concrete. Comparing with Portland cement concrete, the variation rates of chloride diffusion coefficient and chloride ion penetration depth both increase more rapidly for Sulphoaluminate cement concrete after freeze–thaw Cycle.
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Influences of freeze–thaw Cycle and curing time on chloride ion penetration resistance of Sulphoaluminate cement concrete
Construction and Building Materials, 2014Co-Authors: Jun Zhao, Gaochuang Cai, Danying Gao, Shunbo ZhaoAbstract:Abstract In this paper, the influences of freeze–thaw Cycle and curing time on the chloride ion penetration resistance of Portland and Sulphoaluminate cement concretes were researched. Results show that freeze–thaw Cycle and curing time have significant influences on chloride ion penetration resistance of the two cement concretes. Although the chloride diffusion coefficients of the two cement concretes decrease gradually when curing time increases, it is much lower for Sulphoaluminate cement concrete. The chloride diffusion coefficient and chloride ion penetration depth both increase obviously after the two cement concretes were subjected to the freeze–thaw Cycles, which indicates that the freeze–thaw Cycles can accelerate the chloride ion diffusion into the two concretes. Under the same freeze–thaw Cycle and curing time, Sulphoaluminate cement concrete has much better chloride ion penetration resistance than Portland cement concrete. Comparing with Portland cement concrete, the variation rates of chloride diffusion coefficient and chloride ion penetration depth both increase more rapidly for Sulphoaluminate cement concrete after freeze–thaw Cycle.
Setareh Ghorban Shiroodi - One of the best experts on this subject based on the ideXlab platform.
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influence of xanthan curdlan hydrogel complex on freeze thaw stability and rheological properties of whey protein isolate gel over multiple freeze thaw Cycle
Journal of Food Science, 2015Co-Authors: Setareh Ghorban Shiroodi, Barbara Rasco, Martin Y LoAbstract:UNLABELLED: The effect of adding xanthan-curdlan hydrogel complex (XCHC) at 2 concentrations (0.25 and 0.5% w/w) on the Freeze-Thaw stability of heat-induced whey protein isolate (WPI) gel was investigated. Samples were stored at 4 °C for 24 h before subjected to 5 Freeze-Thaw Cycles alternating between -16 °C (18 h) and 25 °C (6 h). Adding XCHC to the WPI solution resulted in the reduction of a significant amount of syneresis up to 5 repeated Freeze-Thaw Cycles. Addition of XCHC decreased the amount of syneresis from 45% in the control sample (pure WPI gel) to 31.82% and 5.44% in the samples containing 0.25% and 0.5% gum, respectively, after the 5th Freeze-Thaw Cycle. XCHC increased the storage modulus (G') of the gels and minimized the changes of the G' values over the 5 Freeze-Thaw Cycles, indicating improvement of the stability of the system. Furthermore, the minimum protein concentration for gel formation decreased in the presence of the XCHC. Scanning electron microscopy (SEM) images showed that addition of XCHC resulted in the formation of a well-structured gel with numerous small pores in the network, which consequently improved the water retention ability during the temperature abuses up to 5 Freeze-Thaw Cycles. These results have important implications for using XCHC in the formulation of the frozen WPI-based products with improved Freeze-Thaw stability and rheological properties. PRACTICAL APPLICATION: Application of XCHC in the formulation of frozen dairy-based food products has the potential to enhance Freeze-Thaw stability and minimize moisture migration caused by temperature abuses of the products during distribution and consumer application.
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Influence of Xanthan–Curdlan Hydrogel Complex on Freeze‐Thaw Stability and Rheological Properties of Whey Protein Isolate Gel over Multiple Freeze‐Thaw Cycle
Journal of Food Science, 2015Co-Authors: Setareh Ghorban Shiroodi, Barbara Rasco, Y. Martin LoAbstract:UNLABELLED: The effect of adding xanthan-curdlan hydrogel complex (XCHC) at 2 concentrations (0.25 and 0.5% w/w) on the Freeze-Thaw stability of heat-induced whey protein isolate (WPI) gel was investigated. Samples were stored at 4 °C for 24 h before subjected to 5 Freeze-Thaw Cycles alternating between -16 °C (18 h) and 25 °C (6 h). Adding XCHC to the WPI solution resulted in the reduction of a significant amount of syneresis up to 5 repeated Freeze-Thaw Cycles. Addition of XCHC decreased the amount of syneresis from 45% in the control sample (pure WPI gel) to 31.82% and 5.44% in the samples containing 0.25% and 0.5% gum, respectively, after the 5th Freeze-Thaw Cycle. XCHC increased the storage modulus (G') of the gels and minimized the changes of the G' values over the 5 Freeze-Thaw Cycles, indicating improvement of the stability of the system. Furthermore, the minimum protein concentration for gel formation decreased in the presence of the XCHC. Scanning electron microscopy (SEM) images showed that addition of XCHC resulted in the formation of a well-structured gel with numerous small pores in the network, which consequently improved the water retention ability during the temperature abuses up to 5 Freeze-Thaw Cycles. These results have important implications for using XCHC in the formulation of the frozen WPI-based products with improved Freeze-Thaw stability and rheological properties. PRACTICAL APPLICATION: Application of XCHC in the formulation of frozen dairy-based food products has the potential to enhance Freeze-Thaw stability and minimize moisture migration caused by temperature abuses of the products during distribution and consumer application.
