WorldWideScience

Sample records for thawing

  1. Permafrost thaw: Methane origins

    Science.gov (United States)

    Bridgham, Scott D.

    2017-07-01

    Permafrost soils represent a massive pool of organic carbon that could be released to the atmosphere due to future climate change. A study now shows that previously frozen soil carbon contained in peatlands may make a relatively modest contribution to future methane emissions following permafrost thaw.

  2. High risk of permafrost thaw

    Science.gov (United States)

    E.A.G. Schuur; B.W. Abbott; W.B. Bowden; V. Brovkin; P. Camill; J.P. Canadell; F.S. Chapin; T.R. Christensen; J.P. Chanton; P. Ciais; P.M. Crill; B.T. Crosby; C.I. Czimczik; G. Grosse; D.J. Hayes; G. Hugelius; J.D. Jastrow; T. Kleinen; C.D. Koven; G. Krinner; P. Kuhry; D.M. Lawrence; S.M. Natali; C.L. Ping; A. Rinke; W.J. Riley; V.E. Romanovsky; A.B.K. Sannel; C. Schadel; K. Schaefer; Z.M. Subin; C. Tarnocai; M. Turetsky; K. M. Walter-Anthony; C.J. Wilson; S.A. Zimov

    2011-01-01

    Arctic temperatures are rising fast, and permafrost is thawing. Carbon released into the atmosphere from permafrost soils will accelerate climate change, but the magnitude of this effect remains highly uncertain. Our collective estimate is that carbon will be released more quickly than models suggest, and at levels that are cause for serious concern. We calculate that...

  3. Moisture controls decomposition rate in thawing tundra

    Science.gov (United States)

    C.E. Hicks-Pries; E.A.G. Schuur; S.M. Natali; J.G. Vogel

    2013-01-01

    Permafrost thaw can affect decomposition rates by changing environmental conditions and litter quality. As permafrost thaws, soils warm and thermokarst (ground subsidence) features form, causing some areas to become wetter while other areas become drier. We used a common substrate to measure how permafrost thaw affects decomposition rates in the surface soil in a...

  4. High risk of permafrost thaw

    Energy Technology Data Exchange (ETDEWEB)

    Schuur, E.A.G.; Abbott, B.; Koven, C.D,; Riley, W.J.; Subin, Z.M.; al, et

    2011-11-01

    In the Arctic, temperatures are rising fast, and permafrost is thawing. Carbon released to the atmosphere from permafrost soils could accelerate climate change, but the likely magnitude of this effect is still highly uncertain. A collective estimate made by a group of permafrost experts, including myself, is that carbon could be released more quickly than models currently suggest, and at levels that are cause for serious concern. While our models of carbon emission from permafrost thaw are lacking, experts intimately familiar with these landscapes and processes have accumulated knowledge about what they expect to happen, based on both quantitative data and qualitative understanding of these systems. We (the authors of this piece) attempted to quantify this expertise through a survey developed over several years, starting in 2009. Our survey asked experts what percentage of surface permafrost they thought was likely to thaw, how much carbon would be released, and how much of that would be methane, for three time periods and under four warming scenarios that are part of the new IPCC Fifth Assessment Report.

  5. Global Annual Freezing and Thawing Indices

    Data.gov (United States)

    National Aeronautics and Space Administration — The total annual freezing and thawing indices are defined as the cumulative number of degree-days when air temperatures are below and above zero degrees Celsius. The...

  6. Microwave thawing of frozen parenteral solutions.

    Science.gov (United States)

    Walter, C W; Pauly, J A; Ausman, R K; Kundsin, R B; Holmes, C J

    1983-01-01

    A commercially available microwave oven modified for use at medication stations throughout hospitals allows timely thawing of frozen parenteral solutions. The inherent problems of safety and uniform heating have been overcome, thus making possible the preparation, storage, and distribution of admixtures on a regional basis and ensuring the integrity of the product. Most parenteral medications are not degraded by microwave energy, and thawing by microwave energy permits timely administration and allows coordination of medication for a series of patients.

  7. Thaw /thermokarst lakes of the Last Galcial and Early Holocene

    Science.gov (United States)

    van Huissteden, Ko

    2013-04-01

    Thaw (thermokarst) lakes have attracted attention as major sources of CH4, amplifying climate change. Also during the Last Glacial thaw lake sedimentary successions have been deposited; several lacustrine units in sedimentary successions in Western Europe have been attributed to permafrost thaw. Likewise, rapid expansion of thaw lakes has occurred during the last glacial termination, in particular in high northern areas of the Eurasian continent. This suggests that also during the Last Glacial, thaw lake formation and associated methane emission from permafrost may have been a positive feedback to climate warming. In this paper, the sedimentological evidence for past thaw lake formation is assessed and compared with thaw lakes and thaw depressions observed in Eastern Siberia. Several of the Western European successions that are interpreted as thaw lakes may have been rather shallow permafrost thaw features instead of lakes, although larger thaw lakes did exist. In several successions, lake and thaw depression formation could be associated with climate warming during interstadials. The sedimentological evidence is also compared with present-day thaw lake dynamics.The evidence on present-day thaw lake expansion is mixed despite pronounced climate warming in the Arctic, and shows stability, net contraction or expansion of lake area in various regions. The evidence may also differ with lake size: net expansion for smaller lakes and ponds, while the area of larger lakes contracts due to drainage of larger lakes. The assumed existence of a thaw lake cycle, that consists of a repeating cycle of lake formation by permafrost thaw, drainage of lakes and re-establishment of ice-rich permafrost, is crucial in the interpretation of lake area changes as an effect of climate change. The thaw lake cycle implies that expansion or contraction of thaw lake area may not necessarily relate to climate change. However, the existance of a thaw lake cycle is inconclusive, although modeling

  8. BERG2 Micro-computer Estimation of Freeze and Thaw Depths and Thaw Consolidation (PDF file)

    Science.gov (United States)

    1989-06-01

    The BERG2 microcomputer program uses a methology similar to the Modified Berggren method (Aldrich and Paynter, 1953) to estimate the freeze and thaw depths in layered soil systems. The program also provides an estimate of the thaw consolidation in ic...

  9. SLAPex Freeze/Thaw 2015: The First Dedicated Soil Freeze/Thaw Airborne Campaign

    Science.gov (United States)

    Kim, Edward; Wu, Albert; DeMarco, Eugenia; Powers, Jarrett; Berg, Aaron; Rowlandson, Tracy; Freeman, Jacqueline; Gottfried, Kurt; Toose, Peter; Roy, Alexandre; hide

    2016-01-01

    Soil freezing and thawing is an important process in the terrestrial water, energy, and carbon cycles, marking the change between two very different hydraulic, thermal, and biological regimes. NASA's Soil Moisture Active/Passive (SMAP) mission includes a binary freeze/thaw data product. While there have been ground-based remote sensing field measurements observing soil freeze/thaw at the point scale, and airborne campaigns that observed some frozen soil areas (e.g., BOREAS), the recently-completed SLAPex Freeze/Thaw (F/T) campaign is the first airborne campaign dedicated solely to observing frozen/thawed soil with both passive and active microwave sensors and dedicated ground truth, in order to enable detailed process-level exploration of the remote sensing signatures and in situ soil conditions. SLAPex F/T utilized the Scanning L-band Active/Passive (SLAP) instrument, an airborne simulator of SMAP developed at NASA's Goddard Space Flight Center, and was conducted near Winnipeg, Manitoba, Canada, in October/November, 2015. Future soil moisture missions are also expected to include soil freeze/thaw products, and the loss of the radar on SMAP means that airborne radar-radiometer observations like those that SLAP provides are unique assets for freeze/thaw algorithm development. This paper will present an overview of SLAPex F/T, including descriptions of the site, airborne and ground-based remote sensing, ground truth, as well as preliminary results.

  10. Modeled Daily Thaw Depth and Frozen Ground Depth, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains modeled daily thaw depth and freezing depth for the Arctic terrestrial drainage basin. Thaw and freezing depths were calculated over the study...

  11. Permafrost thaw in a nested groundwater-flow system

    Science.gov (United States)

    McKenzie, Jeffery M.; Voss, Clifford I.

    2013-01-01

    Groundwater flow in cold regions containing permafrost accelerates climate-warming-driven thaw and changes thaw patterns. Simulation analyses of groundwater flow and heat transport with freeze/thaw in typical cold-regions terrain with nested flow indicate that early thaw rate is particularly enhanced by flow, the time when adverse environmental impacts of climate-warming-induced permafrost loss may be severest. For the slowest climate-warming rate predicted by the Intergovernmental Panel on Climate Change (IPCC), once significant groundwater flow begins, thick permafrost layers can vanish in several hundred years, but survive over 1,000 years where flow is minimal. Large-scale thaw depends mostly on the balance of heat advection and conduction in the supra-permafrost zone. Surface-water bodies underlain by open taliks allow slow sub-permafrost flow, with lesser influence on regional thaw. Advection dominance over conduction depends on permeability and topography. Groundwater flow around permafrost and flow through permafrost impact thaw differently; the latter enhances early thaw rate. Air-temperature seasonality also increases early thaw. Hydrogeologic heterogeneity and topography strongly affect thaw rates/patterns. Permafrost controls the groundwater/surface-water-geomorphology system; hence, prediction and mitigation of impacts of thaw on ecology, chemical exports and infrastructure require improved hydrogeology/permafrost characterization and understanding

  12. To transfer fresh or thawed embryos?

    DEFF Research Database (Denmark)

    Pinborg, Anja

    2012-01-01

    and multiple pregnancies, thereby increasing the safety for mother and child. Finally the article describes the accumulating literature on perinatal and long-term child outcome after transfer of frozen/thawed embryos, including a discussion on the concerns regarding cryo techniques and their possible roles...... and cons of FER versus fresh-embryo transfer with regard to both single-cycle and cumulative pregnancy and delivery rates. The review discusses the obvious advantages of FER: minimizing the proportion of pharmacological and surgical treatments, and lowering the risk of ovarian hyperstimulation syndrome...

  13. Freezing and thawing or freezing, thawing, and aging effects on beef tenderness.

    Science.gov (United States)

    Grayson, A L; King, D A; Shackelford, S D; Koohmaraie, M; Wheeler, T L

    2014-06-01

    The objective of this study was to determine the effect of freezing and thawing or freezing and thawing with an additional aging period after frozen storage on the tenderness of longissimus lumborum (LL) and semitendinosus (ST) steaks relative to aged, fresh steaks. Left-side LL and ST (n = 35 each) were obtained from U.S. Select carcasses classified at the grading stand by the U.S. Meat Animal Research Center visible and near-infrared spectroscopy tenderness system to have predicted slice shear force greater than 16.5 kg at 14 d postmortem. At 2 d postmortem, 2.54 cm thick steaks were cut from each muscle and assigned to 1 of the following treatments: 2 d fresh (2FRESH), 2 d freeze + thaw (2FREEZE), 2 d freeze + thaw + 12 d age (2FREEZE+12AGE), 14 d fresh (14FRESH), 14 d freeze + thaw (14FREEZE), 14 d freeze + thaw + 14 d age (14FREEZE+14AGE), and 28 d fresh (28FRESH). Steaks assigned to a freezing treatment were frozen at -26°C for 30 d before thawing/cooking or thawing with an additional aging period at 2°C. Slice shear force for LL and ST was lower (P FREEZE (27.4 and 24.5 kg) and 14FREEZE (22.4 and 22.4 kg) compared to 2FRESH (33.0 and 29.2 kg) and 14FRESH (25.3 and 25.5 kg), respectively. Slice shear force for LL and ST was lower (P FREEZE+12AGE (17.8 and 20.8 kg) and 14FREEZE+14AGE (14.6 and 19.0 kg) compared to 14FRESH (25.3 and 25.5 kg) and 28FRESH (18.7 and 21.7 kg), respectively. Desmin degradation for LL was not different (P > 0.05) between 2FREEZE (21.0%) and 2FRESH (14.6%) or between 14FREEZE (40.4%) and 14FRESH (38.4%); however, desmin degradation was higher (P FREEZE+12AGE (46.7%) and 14FREEZE+14AGE (71.1%) when compared to 14FRESH (38.4%) and 28FRESH (60.5%), respectively. Cooking loss for LL was higher (P FREEZE+12AGE (15.2%) compared to 14FRESH (14.0%) but was not different (P > 0.05) between 14FREEZE+14AGE (15.0%) and 28FRESH (14.3%). Freezing and thawing or a combination of freezing, thawing, and aging resulted in increased tenderness for LL

  14. Constraints for the thawing and freezing potentials

    Science.gov (United States)

    Hara, Tetsuya; Suzuki, Anna; Saka, Shogo; Tanigawa, Takuma

    2018-01-01

    We study the accelerating present universe in terms of the time evolution of the equation of state w(z) (redshift z) due to thawing and freezing scalar potentials in the quintessence model. The values of dw/da and d^2w/da^2 at a scale factor of a = 1 are associated with two parameters of each potential. For five types of scalar potentials, the scalar fields Q and w as functions of time t and/or z are numerically calculated under the fixed boundary condition of w(z=0)=-1+Δ. The observational constraint w_obs (Planck Collaboration, arXiv:1502.01590) is imposed to test whether the numerical w(z) is in w_obs. Some solutions show thawing features in the freezing potentials. Mutually exclusive allowed regions in the dw/da vs. d^2w/da^2 diagram are obtained in order to identify the likely scalar potential and even the potential parameters for future observational tests.

  15. The Degree of Permafrost Thawing Determines Arctic Tundra Carbon Balance

    Science.gov (United States)

    Vogel, J. G.; Schuur, E. A.; Sickman, J.; Lee, H.; Trucco, C.

    2007-12-01

    In interior Alaska, we measured gross photosynthesis (GP), ecosystem respiration (ER), and net ecosystem exchange (NEE) near a permafrost monitoring borehole that has recorded an increase in permafrost temperatures during the last 22 years. From May 2004 to May 2006, ecosystem C exchange measurements were made with static and automatic chambers in a moist acidic tundra ecosystem. A gradient in degree of permafrost thaw was used to select three sites (Minimal, Moderate and Severe Thaw) that corresponded to an increase in thermokarst occurrence. Between June 1 and August 30, the Severe and Moderate Thaw sites had significantly greater C uptake (GPP) (pproductivity. However, greater winter ER from the Severe Thaw site caused it to be a source (negative NEE, -128 g C m-2) of carbon over three years. The Moderate Thaw site was a carbon sink (52 g C m- 2), while the Minimal Thaw site was near carbon neutral (-7 g C m-2). In the spring and fall, carbon uptake correlated with the occurrence of plant functional groups (sedges, evergreen shrubs) that maintain green foliage and can photosynthesize under cold conditions. Both of these functional groups decreased inside thermokarst. In the winter, the Severe Thaw site lost 34% more C than the other two sites, likely due to warmer deep soil temperatures. As permafrost thaw proceeds, increasing ecosystem C loss may occur during the winter, spring, and fall due to the unique biotic and abiotic characteristics of thermokarst.

  16. Methane emissions from permafrost thaw lakes limited by lake drainage.

    NARCIS (Netherlands)

    van Huissteden, J.; Berrittella, C.; Parmentier, F.J.W.; Mi, Y.; Maximov, T.C.; Dolman, A.J.

    2011-01-01

    Thaw lakes in permafrost areas are sources of the strong greenhouse gas methane. They develop mostly in sedimentary lowlands with permafrost and a high excess ground ice volume, resulting in large areas covered with lakes and drained thaw-lake basins (DTLBs; refs,). Their expansion is enhanced by

  17. Multi-Scale Process of Soil Freezing, Thawing, and Thaw-Settlement

    Science.gov (United States)

    2013-02-18

    2010): 583. doi: 08/11/2011 2.00 Radoslaw L. Michalowski, Tabetha Martel. Stability Charts for 3D Failures of Steep Slopes Subjected to Seismic ...subjected to seismic excitation, Geo-Frontiers 2011, Dallas, TX.. 2011/03/13 00:00:00, . : , 08/09/2011 6.00 Radoslaw L. Michalowski, Srinivasa S...first freeze-thaw cycle. Artificial ground freezing applied in soft soil construction ( tunneling , excavations), and pipelines transporting chilled

  18. Characteristics of frozen colostrum thawed in a microwave oven

    Energy Technology Data Exchange (ETDEWEB)

    Jones, L.R.; Taylor, A.W.; Hines, H.C.

    1987-09-01

    Use of a microwave oven to thaw frozen colostrum was evaluated. Colostrum was collected from nine cows, four of which were immunized to produce specific colostral antibodies. Colostrum from each cow was frozen, subsequently thawed, and pooled. One-liter aliquots of the pooled colostrum were frozen and assigned randomly to three thawing treatments. Colostrum was thawed using one of three regimens: 10 min in a microwave oven at full power (650 W), 17 min in a microwave oven at half power (325 W), and 25 min in 45 degrees C water. Colostrum thawed in the microwave oven was slightly coagulated and had lower volume and total protein content than colostrum thawed in water. Casein and pH were not different among treatments. Both concentration and total content of immunoglobulin A were higher in the control than in microwave treatments. Neither amount nor concentration of immunoglobulin G and immunoglobulin M were different among treatments. Immunological activity, measured by a hemolytic test, was lower for microwave treatments than the control but did not differ between microwave treatments. Frozen colostrum thawed in a microwave oven should provide a reasonable source of colostrum when fresh high quality colostrum is not available.

  19. Freeze-Thaw Durability of Air-Entrained Concrete

    Directory of Open Access Journals (Sweden)

    Huai-Shuai Shang

    2013-01-01

    Full Text Available One of the most damaging actions affecting concrete is the abrupt temperature change (freeze-thaw cycles. The types of deterioration of concrete structures by cyclic freeze-thaw can be largely classified into surface scaling (characterized by the weight loss and internal crack growth (characterized by the loss of dynamic modulus of elasticity. The present study explored the durability of concrete made with air-entraining agent subjected to 0, 100, 200, 300, and 400 cycles of freeze-thaw. The experimental study of C20, C25, C30, C40, and C50 air-entrained concrete specimens was completed according to “the test method of long-term and durability on ordinary concrete” GB/T 50082-2009. The dynamic modulus of elasticity and weight loss of specimens were measured after different cycles of freeze-thaw. The influence of freeze-thaw cycles on the relative dynamic modulus of elasticity and weight loss was analyzed. The findings showed that the dynamic modulus of elasticity and weight decreased as the freeze-thaw cycles were repeated. They revealed that the C30, C40, and C50 air-entrained concrete was still durable after 300 cycles of freeze-thaw according to the experimental results.

  20. Causes of warming and thawing permafrost in Alaska

    National Research Council Canada - National Science Library

    Osterkamp, T. E

    2007-01-01

    There is a perception that climatic warming was the cause of the twentieth‐century global warming and thawing of permafrost and associated terrain instability (thermokarst) [ Gore , 2006; Perkins , 2007; Zielinski , 2007; Delisle , 2007...

  1. Optimal boundary control of a contact thawing process for foodstuff

    OpenAIRE

    Backi, Christoph Josef; Leth, John; Gravdahl, Jan Tommy

    2016-01-01

    In this work an approach for thawing blocks of foodstuff, in particular fish, is introduced. The functional principle is based on plate freezer technology, which has been used in industry for decades. The aim of this work is to describe the temperature dynamics of this thawing process by means of partial differential equations (PDEs) and control the boundary conditions in an optimal way. The PDE describing the temperature dynamics is based on the diffusion equation with state-dependent parame...

  2. Seasonal thaw settlement at drained thermokarst lake basins, Arctic Alaska

    Science.gov (United States)

    Liu, Lin; Schaefer, Kevin; Gusmeroli, Alessio; Grosse, Guido; Jones, Benjamin M.; Zhang, Tinjun; Parsekian, Andrew; Zebker, Howard

    2014-01-01

    Drained thermokarst lake basins (DTLBs) are ubiquitous landforms on Arctic tundra lowland. Their dynamic states are seldom investigated, despite their importance for landscape stability, hydrology, nutrient fluxes, and carbon cycling. Here we report results based on high-resolution Interferometric Synthetic Aperture Radar (InSAR) measurements using space-borne data for a study area located on the North Slope of Alaska near Prudhoe Bay, where we focus on the seasonal thaw settlement within DTLBs, averaged between 2006 and 2010. The majority (14) of the 18 DTLBs in the study area exhibited seasonal thaw settlement of 3–4 cm. However, four of the DTLBs examined exceeded 4 cm of thaw settlement, with one basin experiencing up to 12 cm. Combining the InSAR observations with the in situ active layer thickness measured using ground penetrating radar and mechanical probing, we calculated thaw strain, an index of thaw settlement strength along a transect across the basin that underwent large thaw settlement. We found thaw strains of 10–35% at the basin center, suggesting the seasonal melting of ground ice as a possible mechanism for the large settlement. These findings emphasize the dynamic nature of permafrost landforms, demonstrate the capability of the InSAR technique to remotely monitor surface deformation of individual DTLBs, and illustrate the combination of ground-based and remote sensing observations to estimate thaw strain. Our study highlights the need for better description of the spatial heterogeneity of landscape-scale processes for regional assessment of surface dynamics on Arctic coastal lowlands.

  3. Technological, chemical, sensory, and microbiological examination of frozen chicken as affected by microwave thawing

    OpenAIRE

    Kenawi M.A.

    2005-01-01

    The effect of microwave heating as a thawing method on physical, chemical sensory, and microbiological properties of frozen chicken was investigated in comparison with other thawing methods (at ambient temperature, in refrigerator, and in running tap water). Microwave thawed chicken had the highest taste panel scores and the lowest drip percentage loss compared with the other thawing methods. Thiobarbituric acid value (TBA) remarkably increased the samples thawed at ambient temperature or und...

  4. Meat Quality of Chicken Breast Subjected to Different Thawing Methods

    Directory of Open Access Journals (Sweden)

    MR Oliveira

    2015-06-01

    Full Text Available Freezing is one of the methods to preserve and guarantee the quality of meat until it reaches the consumer. Even though freezing is classified as a mild form of preservation, it causes meat changes resulting from the formation of ice crystals that subsequently affect the tenderness and functionality of meat. The aim of this study was to evaluate the physicochemical and structural characteristics of chicken half breast submitted to fast freezing (-36 °C for 2 hours and thawed by five different methods (under refrigeration, in a microwave, in a oven with air circulation, placed in cold water, or at room temperature. After thawing, the following parameters were evaluated: moisture content, drip loss (syneresis, water activity (aw, and shear force. Samples were also histologically evaluated by light microscopy. The results indicated that, despite being submitted to fast freezing, thawing affected (p <0.05 most of the physicochemical and structural properties of the meat, except for aw. Thawing in cold water (packed in low-density polyethylene bags and placed in cold water at approximately 10 °C for 2 hours and 15 minutes presented the best results due to lesser damage to the cell structure, as shown by the lower drip loss, higher moisture content, and greater tenderness of the samples compared to those thawed using the other methods. Histological examination showed that muscle fiber structural features and organization were maintained. Thawing at low temperatures seems to cause less damage to the meat structure and allows maintaining of its properties. It was concluded that the meat quality is not related only with the freezing method, but also with the method and conditions used in thawing.

  5. Discovery of a novel methanogen prevalent in thawing permafrost

    Science.gov (United States)

    Mondav, Rhiannon; Woodcroft, Ben J.; Kim, Eun-Hae; McCalley, Carmody K.; Hodgkins, Suzanne B.; Crill, Patrick M.; Chanton, Jeffrey; Hurst, Gregory B.; Verberkmoes, Nathan C.; Saleska, Scott R.; Hugenholtz, Philip; Rich, Virginia I.; Tyson, Gene W.

    2014-02-01

    Thawing permafrost promotes microbial degradation of cryo-sequestered and new carbon leading to the biogenic production of methane, creating a positive feedback to climate change. Here we determine microbial community composition along a permafrost thaw gradient in northern Sweden. Partially thawed sites were frequently dominated by a single archaeal phylotype, Candidatus ‘Methanoflorens stordalenmirensis’ gen. nov. sp. nov., belonging to the uncultivated lineage ‘Rice Cluster II’ (Candidatus ‘Methanoflorentaceae’ fam. nov.). Metagenomic sequencing led to the recovery of its near-complete genome, revealing the genes necessary for hydrogenotrophic methanogenesis. These genes are highly expressed and methane carbon isotope data are consistent with hydrogenotrophic production of methane in the partially thawed site. In addition to permafrost wetlands, ‘Methanoflorentaceae’ are widespread in high methane-flux habitats suggesting that this lineage is both prevalent and a major contributor to global methane production. In thawing permafrost, Candidatus ‘M. stordalenmirensis’ appears to be a key mediator of methane-based positive feedback to climate warming.

  6. Metagenomic analysis of permafrost microbial community response to thaw

    Energy Technology Data Exchange (ETDEWEB)

    Mackelprang, R.; Waldrop, M.P.; DeAngelis, K.M.; David, M.M.; Chavarria, K.L.; Blazewicz, S.J.; Rubin, E.M.; Jansson, J.K.

    2011-07-01

    We employed deep metagenomic sequencing to determine the impact of thaw on microbial phylogenetic and functional genes and related this data to measurements of methane emissions. Metagenomics, the direct sequencing of DNA from the environment, allows for the examination of whole biochemical pathways and associated processes, as opposed to individual pieces of the metabolic puzzle. Our metagenome analyses revealed that during transition from a frozen to a thawed state there were rapid shifts in many microbial, phylogenetic and functional gene abundances and pathways. After one week of incubation at 5°C, permafrost metagenomes converged to be more similar to each other than while they were frozen. We found that multiple genes involved in cycling of C and nitrogen shifted rapidly during thaw. We also constructed the first draft genome from a complex soil metagenome, which corresponded to a novel methanogen. Methane previously accumulated in permafrost was released during thaw and subsequently consumed by methanotrophic bacteria. Together these data point towards the importance of rapid cycling of methane and nitrogen in thawing permafrost.

  7. Association of Vitamin E with Rapid Thawing on Goat Semen

    Science.gov (United States)

    Penitente-Filho, Jurandy Mauro; Oliveira, Fabrício Albani; Jimenez, Carolina Rodriguez; Dias, Júlio César Oliveira; Oliveira, Gisele Dias; Silveira, Renata Gomes; Silveira, Camila Oliveira; Torres, Ciro Alexandre Alves

    2014-01-01

    The aim of this study was to evaluate the effects of vitamin E associated with rapid thawing on cryopreserved goat semen. Two bucks were used and eight ejaculates per animal were collected using artificial vagina. Semen was diluted with the following treatments: BIOXCELL (control), BIOXCELL + Equex (sodium lauryl sulphate) and BIOXCELL + vitamin E 100 μM. Semen was packaged into 0.25 mL straws and cooled at 5°C for 1 hour. Freezing was performed in liquid nitrogen vapor (−155°C) during 15 minutes. Then, the straws were immersed in liquid nitrogen (−196°C). Straws were thawed at 38°C/60 seconds or at 60°C/7 seconds with immediate sperm analysis. Hypoosmotic swelling test was performed adding a 20 μL aliquot of thawed semen to 1 mL of hypoosmotic solution (100 mOsm·Kg−1) followed by incubation during 60 minutes in water bath (38°C). Vitamin E did not affect any studied parameters (P > 0.05). Nevertheless, defrosting rate of 60°C/7 seconds improved sperm membrane functional integrity (P < 0.05). Current knowledge about goat semen cryopreservation is not sufficient to ensure high post-thawing recovery rates; thus, this study brings important data about using antioxidants and different thawing rates on cryopreservation process. PMID:24955428

  8. Immobilization of biological membranes by sonication and freeze-thawing

    Energy Technology Data Exchange (ETDEWEB)

    Goto, T.; Kikuchi, K. [Akita Univ. (Japan)

    1998-10-01

    A rapid and convenient means of immobilizing biological membranes is described. Sonication for formation of small vesicles, diffusion of the vesicles in support beads, and freeze-thawing is carried out in an immobilized multi-enzyme system. Large amounts of brush border membranes from bovine kidney were immobilized in Sepharose CL-6B, Sephacryl S-500, and Sephacryl S-1000 and increased in that order. For the latter two beads, the amounts were further increased with repetition of freeze-thawing up to a maximum of three times. Particle distribution analysis reveals that small vesicles are enlarged by the freeze-thawing repetition, suggesting an immobilization mode in which enlarged vesicles are physically entrapped in the beads. The bead-immobilized membrane vesicles were relatively stable, exhibiting constant enzyme activities for at least 6 h under packed column operation. 10 refs., 5 figs.

  9. Do thawing and warming affect the integrity of human milk?

    Science.gov (United States)

    Handa, D; Ahrabi, A F; Codipilly, C N; Shah, S; Ruff, S; Potak, D; Williams, J E; McGuire, M A; Schanler, R J

    2014-11-01

    To evaluate the integrity of the human milk (pH, bacterial counts, host defense factors and nutrients) subjected to thawing, warming, refrigeration and maintenance at room temperature. Mothers in the neonatal intensive care unit donated freshly expressed milk. A baseline sample was stored at -80 °C and the remainder of the milk was divided and stored for 7 days at -20 °C. The milk was then subjected to two methods of thawing and warming: tepid water and waterless warmer. Thawed milk also was refrigerated for 24 h prior to warming. Lastly, warmed milk was maintained at room temperature for 4 h to simulate a feeding session. Samples were analyzed for pH, bacterial colony counts, total fat and free fatty acids, and the content of protein, secretory IgA and lactoferrin. Data were analyzed by repeated-measures analysis of variance and paired t test. There were no differences between processing methods and no changes in fat, protein, lactoferrin and secretory immunoglobulin A with processing steps. Milk pH and bacterial colony counts declined while free fatty acids rose with processing. Refrigeration of thawed milk resulted in greater declines in pH and bacteria and increases in free fatty acids. Bacterial colony counts and free fatty acids increased with maintenance at room temperature. The integrity of the milk was affected similarly by the two thawing and warming methods. Thawing and warming change the integrity of previously frozen human milk, but not adversely. Concerns about maintaining warmed milk at room temperature need to be explored.

  10. Consumer Attitudes Toward Storing and Thawing Chicken and Effects of the Common Thawing Practices on Some Quality Characteristics of Frozen Chicken

    Directory of Open Access Journals (Sweden)

    Hakan Benli

    2016-01-01

    Full Text Available In this study, a survey was conducted to both evaluate the consumers’ general attitudes for purchasing and storing the raw chicken and determine the thawing practices used for defrosting frozen chicken at home. About 75% of the consumers indicated purchasing chicken meat at least once a week or more. Furthermore, the majority (82.16% of those who stored at least a portion of the raw chicken stated freezing the raw chicken meat at home. Freezing the chicken meat was considered to have no effect on the quality by 43.49% of the consumers while 56.51% thought that freezing had either negative or positive effects on the quality. The survey study indicated that top five most commonly used thawing practices included thawing on the kitchen counter, thawing in the refrigerator, thawing in the warm water, thawing in the microwave, and thawing under tap water. In addition, an experimental study was conducted to determine the effects of these most commonly used thawing practices on some quality characteristics of the chicken meat including pH, drip loss, cooking loss, color analysis and textural profile analysis. Although, L* value for thawing on the kitchen counter was the lowest, after cooking, none of the thawing treatments have a significant effect on the color values. Thawing in the microwave produced the highest drip loss of 3.47% while the lowest drip loss of 0.62% was observed with thawing in the refrigerator. On the other hand, thawing in the microwave and refrigerator caused the lowest cooking loss values of 18.29% and 18.53%, respectively. Nevertheless, there were no significant differences among textural parameter values of the defrosted and then cooked samples using the home based thawing practices, indicating similar quality characteristics among the samples.

  11. Consumer Attitudes Toward Storing and Thawing Chicken and Effects of the Common Thawing Practices on Some Quality Characteristics of Frozen Chicken.

    Science.gov (United States)

    Benli, Hakan

    2016-01-01

    In this study, a survey was conducted to both evaluate the consumers' general attitudes for purchasing and storing the raw chicken and determine the thawing practices used for defrosting frozen chicken at home. About 75% of the consumers indicated purchasing chicken meat at least once a week or more. Furthermore, the majority (82.16%) of those who stored at least a portion of the raw chicken stated freezing the raw chicken meat at home. Freezing the chicken meat was considered to have no effect on the quality by 43.49% of the consumers while 56.51% thought that freezing had either negative or positive effects on the quality. The survey study indicated that top five most commonly used thawing practices included thawing on the kitchen counter, thawing in the refrigerator, thawing in the warm water, thawing in the microwave, and thawing under tap water. In addition, an experimental study was conducted to determine the effects of these most commonly used thawing practices on some quality characteristics of the chicken meat including pH, drip loss, cooking loss, color analysis and textural profile analysis. Although, L* value for thawing on the kitchen counter was the lowest, after cooking, none of the thawing treatments have a significant effect on the color values. Thawing in the microwave produced the highest drip loss of 3.47% while the lowest drip loss of 0.62% was observed with thawing in the refrigerator. On the other hand, thawing in the microwave and refrigerator caused the lowest cooking loss values of 18.29% and 18.53%, respectively. Nevertheless, there were no significant differences among textural parameter values of the defrosted and then cooked samples using the home based thawing practices, indicating similar quality characteristics among the samples.

  12. Supplementation freeze-thawed media with selenium protect adipose-derived mesenchymal stem cells from freeze-thawed induced injury.

    Science.gov (United States)

    Valadbeygi, Arash; Naji, Tahere; Pirnia, Afshin; Gholami, Mohammadreza

    2016-10-01

    Successful freezed-thaw of adipose-derived mesenchymal stem cells (ADMSCs) could be a major step in regenerative medicine as well as in the cloning of animal breeds. The aim of this study was to evaluate the efficacy of selenium on the optimizing of freezed-thaw media in the ADMSCs. ADMSCs were extracted from NMRI mice and purified with positive selection Monoclonal CD105 Antibody (PE) and negative selection Monoclonal CD31 and CD45 Antibody using MACS method as well as differentiation to adipose and bone tissue. ADMSCs were divided into four groups. ADMSCs were freezed-thaw under standard condition with or without the addition of 5 ng/ml selenium to both the cryopreservation and thawing solutions. Frozen cells were thawed after four months and viability and cytotoxicity of the cells were analyzed by the Trypan blue test and MTT assay respectively. RNA was extracted and cDNA was synthesized and the expression of apoptotic genes (P53, Fas, Bax, Caspase3, and Bcl2) was examined using Real time-PCR Rotor gene 2009. This study compares slow and rapid methods of cryopreservation. After thawing, viability of the cells treated with selenium was higher than the control group in rapid and slow cryopreserved ADMSCs. Also, the percentage of living cells in the slow cooling method was considerably more than with the rapid cooling method. After analysis of the results using Real time-PCR, the Bcl2 gene was shown to be expressed in both the rapid and slow cooling methods. In the rapid cooling group in addition to the BCL-2 gene, p53 was also expressed. It appears that selenium prevented the apoptotic genes from expression due to its anti-apoptotic effects. The slow cooling method is better and more optimized for ADMSCs protecting them from oxidative damage to a greater extent compared to the rapid cooling method. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. The factors affecting the outcome of frozen–thawed embryo transfer cycle

    Directory of Open Access Journals (Sweden)

    Mahnaz Ashrafi

    2011-06-01

    Conclusion: Protocol type, gonadotrophin preparations, fresh-cycle outcome, endometrial thickness and the numbers of obtained oocytes, embryos, and high-quality thawed embryos transferred are the factors affecting pregnancy outcome of frozen–thawed embryo transfer.

  14. Evaluation of the ovarian reserve in women transplanted with frozen and thawed ovarian cortical tissue

    DEFF Research Database (Denmark)

    Greve, Tine; Schmidt, Kirsten Tryde; Kristensen, Stine Gry

    2012-01-01

    To investigate ovarian reserve and ovarian function in women transplanted with frozen/thawed ovarian tissue.......To investigate ovarian reserve and ovarian function in women transplanted with frozen/thawed ovarian tissue....

  15. Methane emissions proportional to permafrost carbon thawed in Arctic lakes since the 1950s

    OpenAIRE

    Walter Anthony, Katey; Daanen, Ronald; Anthony, Peter; Schneider von Deimling, Thomas; Ping, Chien-Lu; Chanton, Jeffrey P.; Grosse, Guido

    2016-01-01

    Permafrost thaw exposes previously frozen soil organic matter to microbial decomposition. This process generates methane and carbon dioxide, and thereby fuels a positive feedback process that leads to further warming and thaw. Despite widespread permafrost degradation during the past 40 years, the degree to which permafrost thaw may be contributing to a feedback between warming and thaw in recent decades is not well understood. Radiocarbon evidence of modern emissions of ancient permafrost ca...

  16. High biolability of ancient permafrost carbon upon thaw

    NARCIS (Netherlands)

    Vonk, J.E.; Mann, P.J.; Davydov, S.; Davydova, A.; Spencer, R.G.M.; Schade, J.; Sobczak, W.V.; Zimov, S.; Bulygina, E.; Eglinton, T.I.; Holmes, R.M.

    2013-01-01

    Ongoing climate warming in the Arctic will thaw permafrost and remobilize substantial terrestrial organic carbon (OC) pools. Around a quarter of northern permafrost OC resides in Siberian Yedoma deposits, the oldest form of permafrost carbon. However, our understanding of the degradation and

  17. High biolability of ancient permafrost carbon upon thaw

    NARCIS (Netherlands)

    Vonk, Jorien E.; Mann, Paul J.; Davydov, Sergey; Davydova, Anna; Spencer, Robert G. M.; Schade, John; Sobczak, William V.; Zimov, Nikita; Zimov, Sergei; Bulygina, Ekaterina; Eglinton, Timothy I.; Holmes, Robert M.

    2013-01-01

    Ongoing climate warming in the Arctic will thaw permafrost and remobilize substantial terrestrial organic carbon (OC) pools. Around a quarter of northern permafrost OC resides in Siberian Yedoma deposits, the oldest form of permafrost carbon. However, our understanding of the degradation and fate of

  18. Effects of Thawing Methods on the Stability of Cloxacillin Sodium ...

    African Journals Online (AJOL)

    Cloxacillin sodium and benzathine benzylpenicllin powdered injection were reconstituted in three different injectable fluids: 0.9% sodium chloride, 5% dextrose and water for injection. These drug solutions were frozen using domestic refrigerator (0-4oC) and defrozen using microwave oven and room temperature thawing ...

  19. Sperm vacuoles are not modified by freezing--thawing procedures.

    Science.gov (United States)

    Gatimel, Nicolas; Leandri, Roger; Parinaud, Jean

    2013-03-01

    Since the development of the motile sperm organellar morphology examination (MSOME) in 2001 for observing the cephalic vacuoles at high magnification, no study as yet assessed the effect of cryopreservation on these vacuoles, although sperm freezing-thawing procedures are known to affect sperm quality. Examination of the vacuoles before and after freezing-thawing would indicate whether the same normality criteria can be applied for frozen as for fresh spermatozoa when performing intracytoplasmic morphologically selected sperm injection. In 27 sperm samples from fertile men, analysis of conventional sperm parameters (motility, vitality, percentage of normal forms) and a morphological analysis at high magnification (×6000) using image analysis software was performed before freezing and after thawing. Whereas there were expected decreases in motility (Pvacuole area, total vacuole area, vacuole area in the anterior, median and basal parts of the head, percentage of spermatozoa with a vacuole area ≤6.5% and percentage of spermatozoa with a vacuole area >13%). Freezing-thawing procedures have no effect on human sperm vacuoles. Copyright © 2012 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.

  20. Resistance to freezing and thawing of mortar specimens made from ...

    Indian Academy of Sciences (India)

    Resistance to freezing and thawing of mortar specimens made from sulphoaluminate–belite cement (M–SAB) is compared with that of mortars made from portland cement (M–PC). The results suggest that larger median radius of the pores and total porosity of M–SAB compared to those of M–PC are primarily caused by the ...

  1. The Impact of Freeze-Thaw Cycles on Epinephrine.

    Science.gov (United States)

    Beasley, Heather; Ng, Pearlly; Wheeler, Albert; Smith, William R; McIntosh, Scott E

    2015-12-01

    Epinephrine is the first-line medical treatment for anaphylaxis, a life-threatening allergic syndrome. To treat anaphylaxis, backcountry recreationalists and guides commonly carry epinephrine autoinjectors. Epinephrine may be exposed to cold temperatures and freezing during expeditions. An epinephrine solution must contain 90% to 115% of the labeled epinephrine amount to meet United States Pharmacopeia standards. The purpose of this study was to determine whether freeze-thaw cycles alter epinephrine concentrations in autoinjectors labeled to contain 1.0 mg/mL epinephrine. A further objective was to determine whether samples continued to meet United States Pharmacopeia concentration standards after freeze-thaw cycles. Epinephrine from 6 autoinjectors was extracted and divided into experimental and control samples. The experimental samples underwent 7 consecutive 12-hour freeze cycles followed by 7 12-hour thaw cycles. The control samples remained at an average temperature of 23.1°C for the duration of the study. After the seventh thaw cycle, epinephrine concentrations were measured using a high-performance liquid chromatography assay with mass spectrometry detection. The mean epinephrine concentration of the freeze-thaw samples demonstrated a statistically significant increase compared with the control samples: 1.07 mg/mL (SD ± 8.78; 95% CI, 1.04 to 1.11) versus 0.96 mg/mL (SD ± 6.81; 95% CI, 0.94 to 0.99), respectively. The maximal mean epinephrine concentration in the experimental freeze-thaw group was 1.12 mg/mL, which still fell within the range of United States Pharmacopeia standards for injectables (0.90 to 1.15 mg/mL). Although every attempt should be made to prevent freezing of autoinjectors, this preliminary study demonstrates that epinephrine concentrations remain within 90% to 115% of 1.0 mg/mL after multiple freeze-thaw cycles. Copyright © 2015 Wilderness Medical Society. Published by Elsevier Inc. All rights reserved.

  2. The effects of permafrost thaw on soil hydrologic, thermal, and carbon dynamics in an Alaskan peatland

    Science.gov (United States)

    Jonathan A. O' Donnell; M.Torre Jorgenson; Jennifer W. Harden; A.David McGuire; Mikhail Z. Kanevskiy; Kimberly P. Wickland

    2012-01-01

    Recent warming at high-latitudes has accelerated permafrost thaw in northern peatlands, and thaw can have profound effects on local hydrology and ecosystem carbon balance. To assess the impact of permafrost thaw on soil organic carbon (OC) dynamics, we measured soil hydrologic and thermal dynamics and soil OC stocks across a collapse-scar bog chronosequence in interior...

  3. Optimal freezing and thawing for the survival of peripheral nerves in severed rabbit limbs.

    Science.gov (United States)

    Zhu, Zexing; Qiao, Lin; Zhao, Yandong; Zhang, Shuming

    2014-01-01

    This study aimed to investigate the optimal freezing and thawing procedures for the survival of peripheral nerves in severed rabbit limbs. Twenty New Zealand White rabbits were randomized into four groups: normal control, slow-freezing fast-thawing, slow-freezing slow-thawing, fast-freezing fast-thawing, with five animals in each group. The hind limbs of the rabbits were severed at 1 cm above the knee joint. The severed limbs were cryopreserved with various freezing and thawing procedures. The sciatic nerves were harvested and trypsinized into single nerve fibers for morphological evaluation. The cell viability of the nerve fibers was examined by staining with Calcein-AM and propidium iodide. The fluorescent intensity of the nerve fibers was measured with a laser scanning confocal microscope. The morphology of the nerve fibers in the slow-freezing fast-thawing group was very similar with that of the normal control group, with only mild demyelination. The slow-freezing fast-thawing group and slow-freezing slow-thawing group showed severely damaged nerve fibers. The fluorescent intensities of the nerve fibers was significantly different among the four groups, with a decreasing order of normal control, slow-freezing fast-thawing, slow-freezing slow-thawing, and fast-freezing fast-thawing (P freezing fast thawing has the minimal effects on the survival of nerve fibers in severed rabbit limbs.

  4. Freeze/thaw stress in Ceanothus of southern California chaparral.

    Science.gov (United States)

    Ewers, Frank W; Lawson, Michael C; Bowen, Timothy J; Davis, Stephen D

    2003-07-01

    Freeze/thaw stress was examined in chaparral shrubs of the genus Ceanothus to determine the interactive effects of freezing and drought and to consider which is the more vulnerable component, the living leaves (symplast) or the non-living water transport system (apoplast). We hypothesized that where Ceanothus species co-occurred, the more inland species C. crassifolius would be more tolerant of low temperatures than the coastal species C. spinosus, both in terms of leaf survival (LT(50), or the temperature at which there is 50% loss of function or viability) and in terms of resistance to freezing-induced embolism (measurements of percent loss hydraulic conductivity due to embolism following freeze/thaw). Cooling experiments on 2 m long winter-acclimated shoots resulted in LT(50) values of about -10 degrees C for C. spinosus versus -18 degrees C for C. crassifolius. Freeze-thaw cycles resulted in no change in embolism when the plants were well hydrated (-0.7 to -2.0 MPa). However, when plants were dehydrated to -5.0 MPa, C. spinosus became 96% embolized with freeze/thaw, versus only 61% embolism for C. crassifolius. Stems of C. crassifolius became 90% and 97% embolized at -6.6 and -8.0 MPa, respectively, meaning that even in this species, stems could be more vulnerable than leaves under conditions of extreme water stress combined with freeze/thaw events. The dominance of C. crassifolius at colder sites and the restriction of C. spinosus to warmer sites are consistent with both the relative tolerance of their symplasts to low temperatures and the relative tolerance of their apoplasts to freeze events in combination with drought stress.

  5. Microbial mediators of carbon fate in thawing permafrost: connecting microbial activity to geochemistry across an in situ thaw gradient

    Science.gov (United States)

    Kim, E.; Mondav, R.; Woodcroft, B. J.; Hodgkins, S. B.; McCalley, C. K.; Wehr, R.; Logan, T.; VerBerkmoes, N. C.; Crill, P. M.; Chanton, J.; Saleska, S. R.; Rich, V. I.; Tyson, G. W.

    2012-12-01

    Permafrost holds approximately one third of global soil carbon in a relatively unavailable form. Climate change is predicted to virtually eliminate permafrost by the end of the century. The fate of the stored carbon will be driven by local geohydrology and mediated by microbial carbon transformations. Predicting thaw-induced feedbacks to climate change requires improving our understanding of concomitant changes in microbial activity, particularly in CO2 fixation, organic matter degradation, and CH4 cycling. Our team is using diverse geochemical and molecular measurements to track changes in carbon cycling and microbial communities across a natural permafrost thaw gradient. The gradient habitats are highly instrumented for ecological, hydrologic, and biogeochemical monitoring, and the thaw progression has been documented over decades. Permafrost thaw has caused slumping ground level and progressive changes in hydrology and plant composition, culminating in sedge-dominated fen wetland. Although this endpoint habitat supports higher plant productivity, there is a net increase in radiative forcing due to high methane emissions. This natural laboratory permits the examination of in situ changes in microbial composition and activity across thaw-induced habitat change. Specifically, taxonomic and metabolic profiling (16S rRNA gene amplicon, metagenomic and metaproteomic sequencing) is linking microbial metabolisms to synoptic geochemistry. Community data have revealed the presence of a novel highly active methanogen from the euryarchaeal lineage Rice Cluster-II. The abundance and distribution of RC-II across the thaw gradient habitats correlate to methane emission. The 2.1Mb RC-II genome (in 117 contigs, median 47kb, longest 135kb) was assembled from metagenomic data. The genome suggests the ability to perform hydrogenotrophic methanogenesis. To link resident microbes to active carbon cycling, we determined in situ community global protein expression profiles (i

  6. Phenome data - Freeze-thaw stress - DGBY | LSDB Archive [Life Science Database Archive metadata

    Lifescience Database Archive (English)

    Full Text Available List Contact us DGBY Phenome data - Freeze-thaw stress Data detail Data name Phenome data - Freeze-thaw stress... DOI 10.18908/lsdba.nbdc00953-006 Description of data contents Yeasts used in bread making are exposed to freeze-thaw stress...were components of vacuolar H + -ATPase. Next, the cross-sensitivity of the freeze-thaw-sensitive mutants to oxidative stress... and to cell wall stress was studied; both of these are environmental stress...es closely related to freeze-thaw stress. The results showed that defects in the functions of va

  7. Artificial insemination with seminal plasma improves the reproductive performance of frozen-thawed boar epididymal spermatozoa.

    Science.gov (United States)

    Okazaki, Tetsuji; Akiyoshi, Teiichi; Kan, Masakazu; Mori, Manabu; Teshima, Hisanori; Shimada, Masayuki

    2012-01-01

    Frozen-thawed epididymal spermatozoa have good fertilization capability in vitro; however, their artificial insemination conception rate is less than half of that of frozen-thawed ejaculated spermatozoa. Because the addition of seminal plasma to the thawing solution enhances the in vivo fertilizing ability of frozen-thawed ejaculated spermatozoa, we hypothesized that the reproductive performance of frozen-thawed epididymal spermatozoa could also be improved by the inclusion of seminal plasma. When frozenthawed epididymal spermatozoa were incubated for up to 6 hours, the motility of the sperm significantly decreased in a time-dependent manner. The acrosomal membrane was damaged in the majority of frozen-thawed epididymal spermatozoa. The addition of seminal plasma to the thawing solution significantly decreased the percentage of sperm with abnormal acrosomes and increased their total motility in a dose-dependent manner. Furthermore, the addition of seminal plasma reduced the abundance of a 15-kDa tyrosinephosphorylated protein in frozen-thawed sperm, and the maximum effect was observed at 15% (vol/vol) seminal plasma. When cryopreserved epididymal spermatozoa from 3 different boars were thawed with a 15% (vol/vol) seminal plasma-containing solution, the conception rate and mean litter size obtained by artificial insemination were significantly increased as compared with those in the control without seminal plasma. From these results, we concluded that the addition of seminal plasma to the thawing solution is a key step in obtaining an optimal number of piglets by artificial insemination using frozen-thawed boar epididymal spermatozoa.

  8. Freeze/thaw phenomena in concrete at low temperatures

    DEFF Research Database (Denmark)

    Johannesson, Björn

    2007-01-01

    of formed ice at different temperatures and the corresponding measured length changes. The development of cracks in the material structure was indicated by an ultra-sonic technique by measuring on the samples before and after the freeze thaw tests. Further the air bubble structure was investigated using...... a microscopic technique in which air bubble size distributions and the so-called spacing factor, indicating the mean distance between air bubbles, were measured. By analyzing the experimental result it is concluded that damages occur in the temperature range of about -10 oC to 55 oC, when the air content......Freeze/thaw damage in concrete is by general practice concluded to be a problem that can be avoided by using air-entraining agents to develop an air bubble structure in the hardened concrete together with the use of a relatively low water to cement ratio in mix. This fact is true for inner damages...

  9. Novel Membrane System to Automatically Deglycerolize Thawed Frozen Human Blood

    Science.gov (United States)

    1997-04-01

    equivalent to the current Haemonetics 115 device. • Washing frozen/thawed RBCs with the WUP I and WUP II/B/ H devices yielded glycerol washouts of...RHeaton, A, Mesbah -Karimi N, Bross J. Vox Sang 12. Blood Bank Week 1995;12(23):3 36 List of Tables Table 1: Sequence of Events for TBPS Console Table...2..... *1. . ...i.... .,..6. . . ............ 6 ..... 4 E...,..6.... H ..o

  10. SHELF LIFE OF THAWED CRUSTACEANS TREATED WITH SULPHITES

    Directory of Open Access Journals (Sweden)

    G. Smaldone

    2011-04-01

    Full Text Available The quality of fish and fish products is closely related to their freshness. Aim of this research was to evaluate the shelf life of thawed crustaceans (Aristeomorpha foliacea and Nefrops norvegicus which had been treated with sulphites and frozen on board. Organoleptic characteristics and microbiological and chemical parameters were judged favourably up to day 6 and 7 for the shrimps and Norway lobsters, respectively.

  11. Evaluation offreeze-thaw damage in concrete by ultrasonic imaging

    OpenAIRE

    Molero, Miguel; Aparicio, S.; Al‐Assadi, Ghaida; Casati Calzada, María Jesús; Hernández, M. G.; Anaya, J. J.

    2012-01-01

    This work studies the use of ultrasonic imaging as an evaluation tool in concrete subjected to freeze–thaw (F–T) cycles. To evaluate the damage in this deterioration process, ultrasonic velocity and attenuation images have been generated from concrete specimens with and without air-entraining agents. Two parameters have been proposed from these ultrasonic images according to our experimental setup: the non-assessable area proportion (NAAP) and a weighted average velocity in terms of the NAAP....

  12. The calculation of desalination of mineralized porous ice at thawing

    Directory of Open Access Journals (Sweden)

    A. V. Sosnovsky

    2016-01-01

    Full Text Available The results obtained in this work demonstrate that dynamics of desalination of porous ice depends on a mobility of ions of salts, and the mobility is determined by the diffusion coefficient. The ice was made by freezing of mineralized water of different chemical composition. Model calculations of average mineralization of the porous ice at its thawing were made, and the ion concentrations of different salts were defined. Values of the diffusion coefficients of the salt ions in the film of brine ice pellets were obtained by means of comparison of results of measurements and calculations of dynamics of content of the salt ions in a porous ice at its thawing. The diffusion coefficient of ions Na+, Cl−, SO4 2− is by order of magnitude larger than that of Ca2+ and by two orders of magnitudethan HCO3 −. This results in that the content of ions Na+, Cl−, SO42− decreases in porous ice at its thawing 3 times faster than the content of the ions Ca2+. Basing on analysis of chemical composition of drainage water in some regions in Russia a possibility to desalinate the porous ice formed during the winter sprinkling is demonstrated.

  13. Tundra permafrost thaw causes significant shifts in energy partitioning

    Directory of Open Access Journals (Sweden)

    Christian Stiegler

    2016-04-01

    Full Text Available Permafrost, a key component of the arctic and global climate system, is highly sensitive to climate change. Observed and ongoing permafrost degradation influences arctic hydrology, ecology and biogeochemistry, and models predict that rapid warming is expected to significantly reduce near-surface permafrost and seasonally frozen ground during the 21st century. These changes raise concern of how permafrost thaw affects the exchange of water and energy with the atmosphere. However, associated impacts of permafrost thaw on the surface energy balance and possible feedbacks on the climate system are largely unknown. In this study, we show that in northern subarctic Sweden, permafrost thaw and related degradation of peat plateaus significantly change the surface energy balance of three peatland complexes by enhancing latent heat flux and, to less degree, also ground heat flux at the cost of sensible heat flux. This effect is valid at all radiation levels but more pronounced at higher radiation levels. The observed differences in flux partitioning mainly result from the strong coupling between soil moisture availability, vegetation composition, albedo and surface structure. Our results suggest that ongoing and predicted permafrost degradation in northern subarctic Sweden ultimately result in changes in land–atmosphere coupling due to changes in the partitioning between latent and sensible heat fluxes. This in turn has crucial implications for how predictive climate models for the Arctic are further developed.

  14. Arctic climate threat - methane from thawing permafrost; Klimazeitbombe Permafrost

    Energy Technology Data Exchange (ETDEWEB)

    Walter Anthony, Katey [Alaska Univ., Fairbanks, AK (United States). Water and Environmental Research Center

    2010-06-15

    Arctic permafrost is already thawing, creating lakes that emit methane. The heat-trapping gas could dramatically accelerate global warming. How big is the threat? What can be done? Touchdown on the gravel runway at Cherskii in remote northeastern Siberia sent the steel toe of a rubber boot into my buttocks. The shoe had sprung free from gear stuffed between me and my three colleagues packed into a tiny prop plane. This was the last leg of my research teams five-day journey from the University of Alaska Fairbanks across Russia to the Northeast Science Station in the land of a million lakes, which we were revisiting as part of our ongoing efforts to monitor a stirring giant that could greatly speed up global warming. These expeditions help us to understand how much of the perennially frozen ground, known as permafrost, in Siberia and across the Arctic is thawing, or close to thawing, and how much methane the process could generate. The question grips us and many scientists and policy makers because methane is a potent greenhouse gas, packing 25 times more heating power, molecule for molecule, than carbon dioxide. (orig.)

  15. Post-thaw non-cultured and post-thaw cultured equine cord blood mesenchymal stromal cells equally suppress lymphocyte proliferation in vitro.

    Directory of Open Access Journals (Sweden)

    Lynn B Williams

    Full Text Available Multipotent mesenchymal stromal cells (MSC are receiving increased attention for their non-progenitor immunomodulatory potential. Cryopreservation is commonly used for long-term storage of MSC. Post-thaw MSC proliferation is associated with a lag-phase in vitro. How this lag-phase affect MSC immunomodulatory properties is unknown. We hypothesized that in vitro there is no difference in lymphocyte suppression potential between quick-thawed cryopreserved equine cord blood (CB MSC immediately included in mixed lymphocyte reaction (MLR and same MSC allowed post-thaw culture time prior to inclusion in MLR. Cryopreserved CB-MSC from five unrelated foals were compared using two-way MLR. For each of the five unrelated MSC cultures, paired MLR assays of MSC allowed five days of post-thaw culture and MSC included in MLR assay immediately post-thawing were evaluated. We report no difference in the suppression of lymphocyte proliferation by CB-MSC that had undergone post-thaw culture and MSC not cultured post-thaw (p<0.0001. Also, there was no inter-donor variability between the lymphocyte suppressive properties of MSC harvested from the five different donors (p = 0.13. These findings suggest that cryopreserved CB-MSC may have clinical utility immediately upon thawing. One implication hereof is the possibility of using cryopreserved CB-MSC at third party locations without the need for cell culture equipment or competencies.

  16. Effects of a controlled freeze-thaw event on dissolved and colloidal soil organic matter.

    Science.gov (United States)

    Kim, Eun-Ah; Lee, Ha Kyung; Choi, Jung Hyun

    2017-01-01

    This study investigated the effects of the freezing and thawing that accompany the warming process on the composition of the soil organic matter in the dissolved and colloidal fractions. Temperate soil samples were incubated in a refrigerator at 2 °C for 4 weeks and compared with those frozen at -20 °C in the second week followed by thawing at 2 °C to study a freeze-thaw effect with minimal effect from the thawing temperature. The freeze-thaw group was compared with those incubated at 25 °C in the last week to investigate a warming effect after thawing. Thawing at 2 °C after freezing at -20 °C increased the dissolved organic carbon (DOC), but decreased colloidal Ca. The subsequent warming condition greatly increased both DOC and colloidal Ca. The colloidal organic carbon (COC) and dissolved Ca showed rather subtle changes in response to the freeze-thaw and warming treatments compared to the changes in DOC and colloidal Ca. The fluorescence excitation-emission matrix (EEM) and Fourier transformation-infrared spectrometry (FT-IR) results showed that the freeze-thaw and warming treatments gave the opposite effects on the compositions of dissolved humic-like substances, polysaccharides or silicates, and aliphatic alcohols. A principal component analysis (PCA) with the DOC, fluorescence EEM, and FT-IR spectra produced two principal components that successfully distinguished the effects of the freeze-thaw and warming treatments. Due to the contrasting effects of the freeze-thaw and warming treatments, the overall effects of freeze-thaw events in nature on the dissolved and colloidal soil organic matter could vary depending on the thawing temperature.

  17. Efeito do resfriamento do sêmen eqüino sobre sua congelabilidade Effect of freezing and thawing protocols on post-thaw quality of equine semen

    Directory of Open Access Journals (Sweden)

    R. Fürst

    2005-10-01

    Full Text Available Utilizaram-se 25 ejaculados de cinco garanhões da raça Mangalarga Marchador, para avaliar dois protocolos de congelamento. No primeiro tratamento, resfriou-se o sêmen até 5ºC (curva de resfriamento - CR antes do congelamento, no segundo, congelou-se o sêmen sem resfriamento (SC. Compararam-se duas formas de descongelamento, a 37ºC e a 75ºC/sete segundos. Os protocolos foram avaliados pelo teste de termo resistência (TTR - motilidade total e vigor e pela funcionalidade da membrana plasmática (teste hiposmótico e eosina nigrosina. A motilidade total no tempo zero do TTR foi melhor (PTwo freezing protocols and two thawing methods were evaluated on 25 ejaculates from five stallions of the Mangalarga Marchador breed. In the first freezing method, semen was cooled to 5ºC before freezing (CR; and in the second, semen at room temperature was frozen directly (SC. The two thawing methods were thawing semen at 37ºC for 30 seconds versus thawing at 75ºC for 7 seconds. Thawed semen was evaluated by the thermal resistance test (TRT- total motility and vigor and by integrity of sperm membranes (the hypo-osmotic test and the eosine-nigrosine test. Semen that was cooled before freezing had higher (P<0.05 motility immediately post-thaw than semen that was more abruptly frozen (46.7% versus 21.0% for semen thawed at 37ºC and 44.1% versus 24.5% for semen thawed at 75ºC, respectively. At both thawing temperatures, the percentage of live spermatozoa was higher (P<0.05 in CR treatment than in the SC method (71% versus 54.6% for semen thawed at 37ºC and 77.3% versus 54.1% for semen thawed at 75ºC, respectively. The CR treatment also resulted in better hypo-osmotic test results and better semen vigor than did the SC treatment. Semen thawed at 75ºC showed better (P<0.05 vigor than semen thawed at 37ºC, independent of the semen freezing method. In conclusion, there were substantial benefits on subsequent semen quality from cooling of semen before it

  18. Experimental research on durability of recycled aggregate concrete under freeze- thaw cycles

    Science.gov (United States)

    Cheng, Yanqiu; Shang, Xiaoyu; Zhang, Youjia

    2017-07-01

    The freeze-thaw durability of recycled aggregate concrete has significance for the concrete buildings in the cold region. In this paper, the rapid freezing and thawing cycles experience on recycle aggregate concrete was conducted to study on the effects of recycle aggregate amount, water-binder ratio and fly ash on freeze-thaw durability of recycle aggregate concrete. The results indicates that recycle aggregate amount makes the significant influence on the freeze-thaw durability. With the increase of recycled aggregates amount, the freeze-thaw resistance for recycled aggregate concrete decreases. Recycled aggregate concrete with lower water cement ratio demonstrates better performance of freeze-thaw durability. It is advised that the amount of fly ash is less than 30% for admixture of recycled aggregates in the cold region.

  19. Effects of Freezing and Thawing Cycle on Mechanical Properties and Stability of Soft Rock Slope

    OpenAIRE

    Yanlong Chen; Peng Wu; Qing Yu; Guang Xu

    2017-01-01

    To explore the variation laws of mechanical parameters of soft rock and the formed slope stability, an experiment was carried out with collected soft rock material specimens and freezing and thawing cycle was designed. Meanwhile, a computational simulation analysis of the freezing-thawing slope stability was implemented. Key factors that influence the strength of frozen rock specimens were analyzed. Results showed that moisture content and the number of freezing-thawing cycles influenced mech...

  20. Effect of freezing and thawing rates on sperm motility in Bocachico Prochilodus magdalenae (Pisces, Characiformes

    Directory of Open Access Journals (Sweden)

    José G. Martínez

    2013-03-01

    Full Text Available Objective. To determine the freezing and thawing rates necessary to maintain sperm viability during cryopreservation of Bocachico semen. Materials and methods. Four interactional treatments were implemented between two freezing (rapid and slow and two thawing (rapid and slow curves, in a 2x2 factorial as follows: rapid freezing-rapid thawing, rapid freezing-slow thawing, slow freezing-rapid thawing, and slow freezing-slow thawing. After thawing by Sperm Class Analyzer (SCA curvilinear velocity (VCL and straight-line (VSL (μm sec-1 were analyzed; total, rapid, medium, and slow motility, were compared among treatments. Results. The rapid freezing-slow thawing treatment was lethal for all variables of velocity and motility, causing a significant (p<0.01 post-thaw inmotility of 100%. The slow freezing-rapid thawing interaction had a significantly higher effect than the other treatments (p<0.05, particularly on variables such as rapid motility (10.1 ± 1.1%, medium motility (30.16 ± 4.1%, and curvilinear velocity (51.5 ± 4.75 μm sec.-1 also decreased the percentage of sperm with slow motility (41.7 ± 4.45%. Independently of the applied thawing rate, the freezing rate generated the main significant effect on total motility. Conclusions. It is possible to conclude that the interaction effect between freezing and thawing rates is nil (except for slow motility during cryopreservation process. However, the independent effects of these factors (main effects on remaining motility variables are positively significant and decisive to the maintenance of these features, especially the freeze factor (when it is slow. This becomes the first successful report of sperm cryopreservation from Bocachico Prochilodus magdalenae in the world and may be used in conservation programs for this endangered species.

  1. NMR Pore Structure and Dynamic Characteristics of Sandstone Caused by Ambient Freeze-Thaw Action

    Directory of Open Access Journals (Sweden)

    Bo Ke

    2017-01-01

    Full Text Available For a deeper understanding of the freeze-thaw weathering effects on the microstructure evolution and deterioration of dynamic mechanical properties of rock, the present paper conducted the nuclear magnetic resonance (NMR tests and impact loading experiments on sandstone under different freeze-thaw cycles. The results of NMR test show that, with the increase of freeze-thaw cycles, the pores expand and pores size tends to be uniform. The experimental results show that the stress-strain curves all go through four stages, namely, densification, elasticity, yielding, and failure. The densification curve is shorter, and the slope of elasticity curve decreases as the freeze-thaw cycles increase. With increasing freeze-thaw cycles, the dynamic peak stress decreases and energy absorption of sandstone increases. The dynamic failure form is an axial splitting failure, and the fragments increase and the size diminishes with increasing freeze-thaw cycles. The higher the porosity is, the more severe the degradation of dynamic characteristics is. An increase model for the relationships between the porosity or energy absorption and freeze-thaw cycles number was built to reveal the increasing trend with the freeze-thaw cycles increase; meanwhile, a decay model was built to predict the dynamic compressive strength degradation of rock after repeated freeze-thaw cycles.

  2. Effect of thawing methods on frozen semen quality of yak (Poephagus grunniens L. bulls

    Directory of Open Access Journals (Sweden)

    Binod Kumar Dutta Borah

    2015-07-01

    Full Text Available Aim: To evaluate different thawing temperatures and duration on the post-thaw semen quality of Indian yaks bulls. Materials and Methods: Semen ejaculates from four different yak bulls were collected using artificial vagina method and extended with tris extender containing 6.4% glycerol at 35°C, cooled gradually from 35°C to 5°C at 1°C/3 min and equilibrated at 4-5°C for 4 h and frozen in French mini straws using a programmable bio-freezer and finally stored in liquid nitrogen.Thawing of frozen semen straws was carried out using three methods i.e., 35°C for 60 s (thawing method I, 37°C for 30 s (thawing method II and 75°C for 9 s (thawing method III.The post-thaw semen quality parameters assessed were sperm motility, percent live sperm, hypo-osmotic swelling test (HOST-reacted sperm, acrosomal changes, and alanine aminotransferase (ALT and aspartate aminotransferase (AST activities in the extracellular media. Results: The percent sperm motility, total incidence of acrosomal changes, and extracellular release of AST varied significantly (p<0.01 between thawing methods but live sperm and HOST-reacted sperm did not vary significantly between thawing methods.The percent sperm motility of frozen yak semen for thawing method III was significantly (p<0.05 higher than that for thawing methods I and II, the difference between thawing methods I and II being non-significant. The critical difference test revealed that the total incidence of acrosomal changes and extracellular release of AST were significantly (p<0.05 lower when thawing was done using methods I and II than in method III. Conclusion: On the basis of the present experiment, we can conclude that barring the post-thaw sperm motility, thawing of frozen yak semen in water either at 35°C for 60 s or 37°C for 30 s gives better post-thaw semen quality than at 75°C for 09 s.

  3. Influence of cooling and thawing conditions and cryoprotectant concentration on frozen-thawed survival of white-naped crane (Antigone vipio) spermatozoa.

    Science.gov (United States)

    Panyaboriban, Saritvich; Pukazhenthi, Budhan; Brown, Megan E; Crowe, Chris; Lynch, Warren; Singh, Ram P; Techakumphu, Mongkol; Songsasen, Nucharin

    2016-10-01

    To assist in genetic resource management and recovery efforts of the white-naped crane (Antigone vipio), we conducted two experiments to evaluate the effect of cooling condition, thawing rate, and cryoprotectant concentration on sperm survival post-thaw. Semen was collected from four mature males during breeding season (March and April) and evaluated for volume, sperm concentration, motility, and membrane integrity. In Experiment 1, ejaculates (n = 8) were diluted with Beltsville Poultry Semen Extender (BPSE) containing 10% dimethylsulfoxide (Me2SO) and frozen using either one (average cooling rate = 2.5 °C/min) or two step (average cooling rate = 7 and 9 °C/min, respectively) cooling method. The frozen samples were thawed using one of two thawing rates: 37 °C 30 s vs. 4 °C 1 min. In Experiment 2, samples were diluted with crane semen extender containing either 6% or 10% Me2SO, frozen using two-step method and then thawed at 37 °C for 30 s. Both cooling condition (two-step > one-step) and thawing rate (37 °C 30 s > 4 °C 1 min) impacted sperm motility, progression and kinetic characteristics (P  0.05) affect plasma membrane or acrosomal integrity. Concentration of Me2SO did not impact frozen-thaw survival. We conclude that white-naped crane sperm cryopreserved using a combination of two-step cooling and thawing at 37 °C 30 s was superior to other cooling and thawing combinations regarding to sustaining sperm motility with good motility kinetics. Findings represent the first steps towards the development of effective cryopreservation protocols and establishment of a genome resource bank for this threatened species. Copyright © 2016. Published by Elsevier Inc.

  4. Separation of Contaminants in The Freeze/Thaw Process

    Directory of Open Access Journals (Sweden)

    Szpaczyński Janusz A.

    2017-06-01

    Full Text Available These studies examined the concept of concentration and purification of several types of wastewater by freezing and thawing. The experiments demonstrated that freezing of contaminated liquid contributed to concentration of contaminants in solution as well as significant concentration and agglomeration of solid particles. A high degree of purification was achieved for many parameters. The results of comparative laboratory tests for single and multiple freezing are presented. It was found that there was a higher degree of concentration of pollutants in wastewater frozen as man-made snow than in bulk ice. Furthermore, the hypothesis that long storage time of liquid as snow and sufficient temperature gradient metamorphism allows for high efficiency of the concentration process was confirmed. It was reported that the first 30% of the melted liquid volume contained over 90% of all impurities. It gives great opportunities to use this method to concentrate pollutants. The results revealed that the application of this process in full scale is possible. Significant agglomeration of solid particles was also noted. Tests with clay slurry showed that repeated freezing and thawing processes significantly improve the characteristics of slurry for sedimentation and filtration.

  5. Reviews and syntheses: Effects of permafrost thaw on Arctic aquatic ecosystems

    Science.gov (United States)

    Vonk, J.E.; Tank, S.E.; Bowden, W.B.; Laurion, I.; Vincent, W.F.; Alekseychik, P.; Amyot, Y.; Billet, M.F.; Canario, J.; Cory, R.M.; Deshpande, B.N.; Helbig, M.; Jammet, M.; Karlsson, J.; Larouche, J.; MacMillan, G.; Rautio, Milla; Walter Anthony, K.M.; Wickland, Kimberly P.

    2015-01-01

    The Arctic is a water-rich region, with freshwater systems covering about 16 % of the northern permafrost landscape. Permafrost thaw creates new freshwater ecosystems, while at the same time modifying the existing lakes, streams, and rivers that are impacted by thaw. Here, we describe the current state of knowledge regarding how permafrost thaw affects lentic (still) and lotic (moving) systems, exploring the effects of both thermokarst (thawing and collapse of ice-rich permafrost) and deepening of the active layer (the surface soil layer that thaws and refreezes each year). Within thermokarst, we further differentiate between the effects of thermokarst in lowland areas vs. that on hillslopes. For almost all of the processes that we explore, the effects of thaw vary regionally, and between lake and stream systems. Much of this regional variation is caused by differences in ground ice content, topography, soil type, and permafrost coverage. Together, these modifying factors determine (i) the degree to which permafrost thaw manifests as thermokarst, (ii) whether thermokarst leads to slumping or the formation of thermokarst lakes, and (iii) the manner in which constituent delivery to freshwater systems is altered by thaw. Differences in thaw-enabled constituent delivery can be considerable, with these modifying factors determining, for example, the balance between delivery of particulate vs. dissolved constituents, and inorganic vs. organic materials. Changes in the composition of thaw-impacted waters, coupled with changes in lake morphology, can strongly affect the physical and optical properties of thermokarst lakes. The ecology of thaw-impacted lakes and streams is also likely to change; these systems have unique microbiological communities, and show differences in respiration, primary production, and food web structure that are largely driven by differences in sediment, dissolved organic matter, and nutrient delivery. The degree to which thaw enables the delivery

  6. Study on the facilities and procedures for meltwater erosion of thawed soil

    Directory of Open Access Journals (Sweden)

    Yunyun Ban

    2016-06-01

    Full Text Available High erosion rate of seasonal thawed soils by snow- and ice-melting runoff in the high altitude and latitude cold regions has great impacts on ecological systems, industries, agriculture and various manmade infrastructures as well as people's lives. The facilities and procedures are of great importance for the studies on simulating erosion processes of melt-frozen soil. This study focuses on the method and facility for simulating the thawing process of frozen soil. The facility includes soil freezing system, melt-water supply system and experimental flume system for thawed soil erosion. The soil freezing system provides enough space to freeze soil columns in flumes. The water supply system deliveries snow- or ice-melting water flow of constant-rate at 0 °C. The soil flumes of 200 or 300 cm long, 10 cm wide and 12 cm high are designed to be assemble and convenient for soil freezing before they are thawed in one-dimensional manner from top to bottom. The one-dimensional thawing process is realized as follows. The frozen soil flume is put on ice boxes and thermally insulated with heat-insulating materials all around to prevent frozen soil from being thawed from sidewalls and bottom. The soil thaws with this system shows that it can meet the requirements of simulating the process of soil thawing from top to bottom. The thawed soil flumes are connected from end to end to form rills of 6–8 m long to run the erosion experiments under different designed hydraulic condition. The equipment provides facility, method and operation process for simulating one-dimensional soil thawing to serve research on the effect of thawed soil depth on erosion process.

  7. Remote sensing of freeze-thaw transitions in Arctic soils using the complex resistivity method

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Yuxin [Lawrence Berkeley National Laboratory (LBNL); Hubbard, Susan S [Lawrence Berkeley National Laboratory (LBNL); Ulrich, Craig [Lawrence Berkeley National Laboratory (LBNL); Wullschleger, Stan D [ORNL

    2013-01-01

    Our ability to monitor freeze - thaw transitions is critical to developing a predictive understanding of biogeochemical transitions and carbon dynamics in high latitude environments. In this study, we conducted laboratory column experiments to explore the potential of the complex resistivity method for monitoring the freeze - thaw transitions of the arctic permafrost soils. Samples for the experiment were collected from the upper active layer of Gelisol soils at the Barrow Environmental Observatory, Barrow Alaska. Freeze - thaw transitions were induced through exposing the soil column to controlled temperature environments at 4 C and -20 C. Complex resistivity and temperature measurements were collected regularly during the freeze - thaw transitions using electrodes and temperature sensors installed along the column. During the experiments, over two orders of magnitude of resistivity variations were observed when the temperature was increased or decreased between -20 C and 0 C. Smaller resistivity variations were also observed during the isothermal thawing or freezing processes that occurred near 0 C. Single frequency electrical phase response and imaginary conductivity at 1 Hz were found to be exclusively related to the unfrozen water in the soil matrix, suggesting that these geophysical 24 attributes can be used as a proxy for the monitoring of the onset and progression of the freeze - thaw transitions. Spectral electrical responses and fitted Cole Cole parameters contained additional information about the freeze - thaw transition affected by the soil grain size distribution. Specifically, a shift of the observed spectral response to lower frequency was observed during isothermal thawing process, which we interpret to be due to sequential thawing, first from fine then to coarse particles within the soil matrix. Our study demonstrates the potential of the complex resistivity method for remote monitoring of freeze - thaw transitions in arctic soils. Although

  8. Effect of freezing and thawing rates on the post-thaw viability of boar spermatozoa frozen in FlatPacks and Maxi-straws.

    Science.gov (United States)

    Eriksson, B M; Rodriguez-Martinez, H

    2000-11-01

    The effects of different freezing and thawing rates on the post-thaw motility and membrane integrity of boar spermatozoa, processed as split samples in Maxi-straws or flat PET-plastic packages (FlatPack) were studied. A programmable freezing device was used to obtain freezing rates of either 20, 50 or 80 degrees C/min. Thawing of the samples was performed in a bath of circulating water; for 40s at 50 degrees C or 27s at 70 degrees C for Maxi-straws and 23s at 35 degrees C, 13s at 50 degrees C or 8s at 70 degrees C for the FlatPacks. Sperm motility was assessed both visually and with a computer assisted semen analysis (CASA) apparatus, while plasma membrane integrity was assessed using the fluorescent probes Calcein AM and ethidium homodimer-1. Temperature changes during freezing and thawing were monitored in both forms of packaging. Values for motile spermatozoa, sperm velocity and lateral head displacement variables were significantly (pstraws, with superior results at higher thawing rates. Freezing at 50 degrees C/min yielded better motility than 20 or 80 degrees C/min, although the effect was rather small. Neither freezing rate nor thawing rate had any effect on membrane integrity (p>0.05). A significant boar effect was seen for several parameters. The most striking difference in temperature courses between containers was a 4-5-fold lowering of the thawing rate, between -20 and 0 degrees C, in the center of the Maxi-straw, compared with the FlatPack. This is apparently due to the insulating effect of the thawed water in the periphery of the Maxi-straw. The improvement in sperm motility seen when using the FlatPack appears to be related to the rapid thawing throughout the sample, which decreases the risk of cell damage due to recrystallization during thawing. Since sperm motility patterns have been reported to be correlated with fertility both in vitro and in vivo it is speculated that the use of the FlatPack might improve the results when using frozen-thawed

  9. Influence of Xanthan-Curdlan Hydrogel Complex on Freeze-Thaw Stability and Rheological Properties of Whey Protein Isolate Gel over Multiple Freeze-Thaw Cycle.

    Science.gov (United States)

    Shiroodi, Setareh Ghorban; Rasco, Barbara A; Lo, Y Martin

    2015-07-01

    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. 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. © 2015 Institute of Food Technologists®

  10. Soil CO2 production in upland tundra where permafrost is thawing

    Science.gov (United States)

    Hanna Lee; Edward A.G. Schuur; Jason G. Vogel

    2010-01-01

    Permafrost soils store nearly half of global soil carbon (C), and therefore permafrost thawing could lead to large amounts of greenhouse gas emissions via decomposition of soil organic matter. When ice-rich permafrost thaws, it creates a localized surface subsidence called thermokarst terrain, which changes the soil microenvironment. We used soil profile CO2...

  11. Potential Arctic tundra vegetation shifts in response to changing temperature, precipitation and permafrost thaw

    NARCIS (Netherlands)

    Kolk, van der Henk-Jan; Heijmans, M.M.P.D.; Huissteden, van J.; Pullens, J.W.M.; Berendse, F.

    2016-01-01

    Over the past decades, vegetation and climate have changed significantly in the Arctic. Deciduous shrub cover is often assumed to expand in tundra landscapes, but more frequent abrupt permafrost thaw resulting in formation of thaw ponds could lead to vegetation shifts towards graminoid-dominated

  12. Thaw pond development and initial vegetation succession in experimental plots at a Siberian lowland tundra site

    NARCIS (Netherlands)

    Li, Bingxi; Heijmans, Monique M.P.D.; Blok, Daan; Wang, Peng; Karsanaev, Sergey V.; Maximov, Trofim C.; Huissteden, van Jacobus; Berendse, Frank

    2017-01-01

    Background and aims: Permafrost degradation has the potential to change the Arctic tundra landscape. We observed rapid local thawing of ice-rich permafrost resulting in thaw pond formation, which was triggered by removal of the shrub cover in a field experiment. This study aimed to examine the

  13. Reviews and syntheses : Effects of permafrost thaw on Arctic aquatic ecosystems

    NARCIS (Netherlands)

    Vonk, J. E.|info:eu-repo/dai/nl/370832833; Tank, S. E.; Bowden, W. B.; Laurion, I.; Vincent, W. F.; Alekseychik, P.; Amyot, M.; Billet, M. F.; Canário, J.; Cory, R. M.; Deshpande, B. N.; Helbig, M.; Jammet, M.; Karlsson, J.; Larouche, J.; Macmillan, G.; Rautio, M.; Walter Anthony, K. M.; Wickland, K. P.

    2015-01-01

    The Arctic is a water-rich region, with freshwater systems covering about 16 % of the northern permafrost landscape. Permafrost thaw creates new freshwater ecosystems, while at the same time modifying the existing lakes, streams, and rivers that are impacted by thaw. Here, we describe the current

  14. Interactive effects of wildfire and permafrost thaw on peatland carbon cycling

    Science.gov (United States)

    Olefeldt, David; Heffernan, William; Gibson, Carolyn; Burd, Katheryn; Estop-Aragones, Cristian

    2017-04-01

    Boreal peatland complexes in western Canada are fine-scale mosaics of permafrost affected peat plateaus interspersed with Sphagnum dominated thermokarst bogs where permafrost is absent. Wildfire further affects landscape patterning of peatland complexes, where virtually all peat plateaus are in a stage of secondary succession following wildfire. With climate change we expect both permafrost thaw and wildfire activity to increase in these landscapes, and to have important impacts on carbon cycling. In a number of studies, we have used soil chamber techniques to assess the influence of both permafrost thaw and wildfire on soil respiration, net ecosystem exchange and methane emissions. We used chronosequences to assess the influence of time since both permafrost thaw (3 - 15 years) and wildfire (20 - 150 years). Radiocarbon signatures of soil respiration in both burned and thawed locations was used to determine the contribution of aged soil carbon to soil respiration. We furthermore characterized individual and interactive effects of fire and thaw on microbial and photochemical lability of dissolved organic matter. At many field sites it was clear that recent wildfire had accelerated permafrost thaw, and we combined field observations of soil thermal regimes with remote sensing approaches to assess the role of wildfire for accelerating permafrost thaw over the last 50 years at a regional scale. Overall, our results highlight the need to consider both individual and interacting effects of thaw and fire for projections of the future carbon cycling at the regional level.

  15. FREEZE-THAW CYCLING AND COLD TEMPERATURE EFFECTS ON GEOMEMBRANE SHEETS AND SEAMS. Project summary

    Science.gov (United States)

    The effects of freeze-thaw cycling on the tensile strength of 19 geomembranes and 31 different seam types were investigated. The study was performed in three parts using different test conditions. Part I involved incubating unconfined specimens in freeze-thaw cycles and then per...

  16. the effect of pellet volume, dilution rates prefreezing and at thawing

    African Journals Online (AJOL)

    when the semen was thawed and incubated in a solution. The successivestages of acrosome-damage(Fig. 3) observed in this study weresimilar to those reported by Healy (1969),. Nath (1972) and Watson & Martin (1972). The proportion of cells with normal appearing acrosomes after freeze- thawing was, however, higher ...

  17. Fracture Surface Fractal Characteristics of Alkali-Slag Concrete under Freeze-Thaw Cycles

    Directory of Open Access Journals (Sweden)

    Wantong Cai

    2017-01-01

    Full Text Available Fractal theory is introduced in fracture surface research of alkali-slag concrete (ASC under freeze-thaw cycles; crack distribution of ASC fracture surface and freeze-thaw damage zone were calculated. Through fractal analysis of ASC sample fracture surfaces, relevance between section fractal dimension and fracture toughness and relationship between material composition and section fractal dimension are clarified. Results show that the specimen’s cracks before freeze-thaw extend along force direction gently, and there are more twists and turns after freezing and thawing; the fractal dimension D also grows from 1.10 to 1.33. SEM internal microcracks’ D of ASC internal microstructure after freezing and thawing is 1.37; 0 to 300 times ASC fractal dimension under freezing and thawing is between 2.10 and 2.23; with freeze-thaw times increasing, ASC fracture toughness decreases and fractal dimension increases, the fractal dimension and fracture toughness have a good linear relationship, and the fractal dimension can reflect the toughening effect of ASC. It is very feasible to evaluate ASC fracture behaviour under freezing and thawing with the fractal theory. Fractal dimension generally increases with activator solution-slag (A/S for short or slag content. The greater the amount of A/S or slag content, the lower the dimension.

  18. STUDY ON THE DAMAGE MECHANISM OF PORE STRUCTURE IN CONCRETE SUBJECTED TO FREEZE-THAW CYCLES

    Directory of Open Access Journals (Sweden)

    Ben Li

    2015-07-01

    Full Text Available It is well know that freeze-thaw cycles play the most significant role in the durability evolution in concrete structures, freeze-thaw cycles have been accounted as one of the major factors on the damage and demolition of concrete. Microscopic parameters have been used for describing the characterizations of damage in concrete under freeze-thaw actions by researchers. However, their models could not provide specific damage factors or parameters. In this paper, a new damage model and equation based on variations of pore structure in concrete is established. This new pore damage model is used for analysing freeze-thaw damage of concrete and validated by experiments. The results show that the measurement of pore structure becomes larger, the diameters of most probably pore structure, critical pore structure, and the variations of porosity increase with the process of freeze-thaw cycles. The pore damage factor or parameter is suitable for describing the mechanism of freeze-thaw damage. Furthermore, the damage results calculated by this new freeze-thaw damage equation, based on variations of pore structure in concrete gives an excellent correlation with experimental results. This pore damage equation was proved to be effective for evaluating the degradation of concrete which is subjected to freezing and thawing cycles in low or sub-zero regions.

  19. Thaw pond dynamics and carbon emissions in a Siberian lowland tundra landscape

    Science.gov (United States)

    van Huissteden, Ko; Heijmans, Monique; Dean, Josh; Meisel, Ove; Goovaerts, Arne; Parmentier, Frans-Jan; Schaepman-Strub, Gabriela; Belelli Marchesini, Luca; Kononov, Alexander; Maximov, Trofim; Borges, Alberto; Bouillon, Steven

    2017-04-01

    Arctic climate change induces drastic changes in permafrost surface wetness. As a result of thawing ground ice bodies, ice wedge troughs and thaw ponds are formed. Alternatively, ongoing thaw may enhance drainage as a result of increased interconnectedness of thawing ice wedge troughs, as inferred from a model study (Liljedahl et al., 2016, Nature Geoscience, DOI: 10.1038/NGEO2674). However, a recent review highlighted the limited predictability of consequences of thawing permafrost on hydrology (Walvoord and Kurylyk, 2016, Vadose Zone J., DOI:10.2136/vzj2016.01.0010). Overall, these changes in tundra wetness modify carbon cycling in the Arctic and in particular the emissions of CO2 and CH4 to the atmosphere, providing a possibly positive feedback on climate change. Here we present the results of a combined remote sensing, geomorphological, vegetation and biogechemical study of thaw ponds in Arctic Siberian tundra, at Kytalyk research station near Chokurdakh, Indigirka lowlands. The station is located in an area dominated by Pleistocene ice-rich 'yedoma' sediments and drained thaw lake bottoms of Holocene age. The development of three types of ponds in the Kytalyk area (polygon centre ponds, ice wedge troughs and thaw ponds) has been traced with high resolution satellite and aerial imagery. The remote sensing data show net areal expansion of all types of ponds. Next to formation of new ponds, local vegetation change from dry vegetation types to wet, sedge-dominated vegetation is common. Thawing ice wedges and thaw ponds show an increase in area and number at most studied locations. In particular the area of polygon centre ponds increased strongly between 2010 and 2015, but this is highly sensitive to antecedent precipitation conditions. Despite a nearly 60% increase of the area of thawing ice wedge troughs, there is no evidence of decreasing water surfaces by increasing drainage through connected ice wedge troughs. The number of thaw ponds shows an equilibrium

  20. Giant panda (Ailuropoda melanoleuca) sperm morphometry and function after repeated freezing and thawing.

    Science.gov (United States)

    Santiago-Moreno, J; Esteso, M C; Pradiee, J; Castaño, C; Toledano-Díaz, A; O'Brien, E; Lopez-Sebastián, A; Martínez-Nevado, E; Delclaux, M; Fernández-Morán, J; Zhihe, Z

    2016-05-01

    This work examines the effects of subsequent cycles of freezing-thawing on giant panda (Ailuropoda melanoleuca) sperm morphometry and function, and assesses whether density-gradient centrifugation (DGC) can increase the number of freezing-thawing cycles this sperm can withstand. A sperm sample was collected by electroejaculation from a mature giant panda and subjected to five freezing-thawing cycles. Although repeated freezing-thawing negatively affected (P 60% of the sperm cells in both treatments showed acrosome integrity even after the fifth freezing cycle. In fresh semen, the sperm head length was 4.7 μm, the head width 3.6 μm, area 14.3 μm(2) and perimeter length 14.1 μm. The present results suggest that giant panda sperm trends to be resistant to repeated freezing-thawing, even without DGC selection. © 2015 Blackwell Verlag GmbH.

  1. Poorly known microbial taxa dominate the microbiome of permafrost thaw ponds.

    Science.gov (United States)

    Wurzbacher, Christian; Nilsson, R Henrik; Rautio, Milla; Peura, Sari

    2017-08-01

    In the transition zone of the shifting permafrost border, thaw ponds emerge as hotspots of microbial activity, processing the ancient carbon freed from the permafrost. We analyzed the microbial succession across a gradient of recently emerged to older ponds using three molecular markers: one universal, one bacterial and one fungal. Age was a major modulator of the microbial community of the thaw ponds. Surprisingly, typical freshwater taxa comprised only a small fraction of the community. Instead, thaw ponds of all age classes were dominated by enigmatic bacterial and fungal phyla. Our results on permafrost thaw ponds lead to a revised perception of the thaw pond ecosystem and their microbes, with potential implications for carbon and nutrient cycling in this increasingly important class of freshwaters.

  2. X-ray tomography of morphological changes after freeze/thaw in gas diffusion layers.

    Science.gov (United States)

    Je, Junho; Kim, Jongrok; Kaviany, Massoud; Son, Sang Young; Kim, MooHwan

    2011-09-01

    Liquid water produced in a polymer electrolyte membrane fuel cell experiences a freeze/thaw cycle when the cell is switched off and on while operating at ambient temperatures below freezing. This freeze/thaw cycle permanently deforms the polymer electrolyte membrane fuel cell capillary structures and reduces both the cell life and its ability to generate electric power. The X-ray tomography facility at the Pohang Accelerator Laboratory was used to observe the freeze/thaw effects on the gas diffusion layer (GDL), which is the thickest capillary layer in the cell. Morphological changes in the GDL under a water freeze/thaw cycle were observed. A scenario in which freeze/thaw cycles affect fuel cell performance is suggested based on images from X-ray tomography.

  3. THAWING PROCEDURES FOR HOSPITAL-MADE ENTERAL FEEDINGS: SURVIVAL OF COLIFORM AND MESOPHILIC AEROBIC BACTERIA

    Directory of Open Access Journals (Sweden)

    KATHIA ROSSI ROLIM LOPES

    2009-07-01

    Full Text Available

    ABSTRACT: This study had the purpose to observe the effect of thawing procedures on survival of coliform and mesophilic aerobic bacteria in hospital-made enteral feedings. The samples are represented by three different lots. The tests were realized in three moments: immediately after the sample preparation and after freezing during 1 or 2 months. The thawing procedures were denominated convencional and alternative. The first, used by hospital, utilizes water bath at 50ºC, considering the time spent from the total thawing to its distribution in the infirmaries. The second was the fast thawing made by microwaving. The results showed that the reduction of the mesophiles and coliform was related to the time the samples were frozen. The results obtained indicate an advantage of the alternative method, which presented lower total and fecal coliform counts than the conventional one. KEYWORDS: Enteral feedings; thawing; food microbiology.

  4. Behavior of Plain Concrete of a High Water-Cement Ratio after Freeze-Thaw Cycles

    Directory of Open Access Journals (Sweden)

    Huai-Shuai Shang

    2012-09-01

    Full Text Available An experimental study of plain concrete specimens of water-cement ratio 0.55, subjected to 0, 15, 25, 40, 50 and 75 cycles of freeze-thaw was completed. The dynamic modulus of elasticity (DME, weight loss, compressive strength, tensile strength, flexural strength, cleavage strength and stress-strain relationships of plain concrete specimens suffering from freeze-thaw cycles were measured. The experimental results showed that the strength decreased as the freeze-thaw cycles were repeated. A concise mathematic formula between DME, weight loss, mechanical properties and number of freeze-thaw cycles was also established. The influences of freeze-thaw cycles on the DME, weight loss and mechanical properties were analyzed. The experimental results serve as a reference for the maintenance, design and life prediction of dams, hydraulic structures, offshore structures, concrete roads and bridges in cold regions.

  5. Evaluation and Comparison of Freeze-Thaw Tests and Air Void Analysis of Pervious Concrete

    DEFF Research Database (Denmark)

    Lund, Mia Schou Møller; Hansen, Kurt Kielsgaard; Kevern, John T.

    2016-01-01

    Pearl-Chain Bridge technology is an innovative precast arch bridge solution which uses pervious concrete as fill material. To ensure longevity of the bridge superstructure it is necessary that the per-vious concrete fill is designed to be freeze-thaw durable; however, no standards exist on how...... to eval-uate the freeze-thaw resistance of fresh or hardened pervious concrete and correspondingly what constitutes acceptable freeze-thaw durability. A greater understanding of the correlation between the freeze-thaw performance and the air void structure of pervious concrete is needed. In the present...... study six pervious concrete mixes were exposed to freeze-thaw testing, and their air void structure was analyzed using an automated linear-traverse method. It was found that there is a miscorrelation between these two test methods in their assumption of whether or not the large interconnected voids...

  6. Evaluation of Physicochemical Deterioration and Lipid Oxidation of Beef Muscle Affected by Freeze-thaw Cycles

    Science.gov (United States)

    Rahman, M. H.; Hossain, M. M.; Rahman, S. M. E.; Amin, M. R.; Oh, Deog-Hwan

    2015-01-01

    This study was performed to explore the deterioration of physicochemical quality of beef hind limb during frozen storage at −20℃, affected by repeated freeze-thaw cycles. The effects of three successive freeze-thaw cycles on beef hind limb were investigated comparing with unfrozen beef muscle for 80 d by keeping at −20±1℃. The freeze-thaw cycles were subjected to three thawing methods and carried out to select the best one on the basis of deterioration of physicochemical properties of beef. As the number of repeated freeze-thaw cycles increased, drip loss decreased and water holding capacity (WHC) increased (pphysicochemical quality of beef muscle, causing the degradation of its quality. PMID:26877637

  7. The effects of permafrost thaw on soil hydrologic, thermal, and carbon dynamics in an Alaskan peatland

    Science.gov (United States)

    O'Donnell, Jonathan A.; Jorgenson, M. Torre; Harden, Jennifer W.; McGuire, A. David; Kanevskiy, Mikhail Z.; Wickland, Kimberly P.

    2012-01-01

    Recent warming at high-latitudes has accelerated permafrost thaw in northern peatlands, and thaw can have profound effects on local hydrology and ecosystem carbon balance. To assess the impact of permafrost thaw on soil organic carbon (OC) dynamics, we measured soil hydrologic and thermal dynamics and soil OC stocks across a collapse-scar bog chronosequence in interior Alaska. We observed dramatic changes in the distribution of soil water associated with thawing of ice-rich frozen peat. The impoundment of warm water in collapse-scar bogs initiated talik formation and the lateral expansion of bogs over time. On average, Permafrost Plateaus stored 137 ± 37 kg C m-2, whereas OC storage in Young Bogs and Old Bogs averaged 84 ± 13 kg C m-2. Based on our reconstructions, the accumulation of OC in near-surface bog peat continued for nearly 1,000 years following permafrost thaw, at which point accumulation rates slowed. Rapid decomposition of thawed forest peat reduced deep OC stocks by nearly half during the first 100 years following thaw. Using a simple mass-balance model, we show that accumulation rates at the bog surface were not sufficient to balance deep OC losses, resulting in a net loss of OC from the entire peat column. An uncertainty analysis also revealed that the magnitude and timing of soil OC loss from thawed forest peat depends substantially on variation in OC input rates to bog peat and variation in decay constants for shallow and deep OC stocks. These findings suggest that permafrost thaw and the subsequent release of OC from thawed peat will likely reduce the strength of northern permafrost-affected peatlands as a carbon dioxide sink, and consequently, will likely accelerate rates of atmospheric warming.

  8. Comparison of the Viability of Cryopreserved Fat Tissue in Accordance with the Thawing Temperature

    Directory of Open Access Journals (Sweden)

    So-Min Hwang

    2015-03-01

    Full Text Available BackgroundAdipose tissue damage of cryopreserved fat after autologous fat transfer is inevitable in several processes of re-transplantation. This study aims to compare and analyze the survivability of adipocytes after thawing fat cryopreserved at -20℃ by using thawing methods used in clinics.MethodsThe survival rates of adipocytes in the following thawing groups were measured: natural thawing at 25℃ for 15 minutes; natural thawing at 25℃ for 5 minutes, followed by rapid thawing at 37℃ in a water bath for 5 minutes; and rapid thawing at 37℃ for 10 minutes in a water bath. The survival rates of adipocytes were assessed by measuring the volume of the fat layer in the top layers separated after centrifugation, counting the number of live adipocytes after staining with trypan blue, and measuring the activity of mitochondria in the adipocytes.ResultsIn the group with rapid thawing for 10 minutes in a water bath, it was observed that the cell count of live adipocytes and the activity of the adipocyte mitochondria were significantly higher than in the other two groups (P<0.05. The volume of the fat layer separated by centrifugation was also measured to be higher, which was, however, not statistically significant.ConclusionsIt was shown that the survival rate of adipocytes was higher when the frozen fat tissue was thawed rapidly at 37℃. It can thus be concluded that if fats thawed with this method are re-transplanted, the survival rate of cryopreserved fats in transplantation will be improved, and thus, the effect of autologous fat transfer will increase.

  9. Permafrost thawing from different technical systems in Arctic regions

    Science.gov (United States)

    Filimonov, M.; Vaganova, N.

    2017-06-01

    A new three-dimensional model of thermal interaction in a “heat source-and-soil” system is proposed to study the process of permafrost degradation from various engineering facilities operating in the Arctic regions, taking into account a number of physical and climatic factors that affect the heat distribution. On the base of the proposed model, a software complex was developed to predict long-term dynamics of permafrost thawing in the upper layer of soil, and this approach was used in the design of 11 northern Russian oil and gas fields and is in a good agreement with numerical rezults and experimental data. Numerical calculations are presented for illustration the possibility of carrying out long-term forecasts for the determination of permafrost zone defrosting during operation of production wells in northern oil and gas field.

  10. Metagenomes from thawing low-soil-organic-carbon mineral cryosols and permafrost of the canadian high arctic.

    Science.gov (United States)

    Chauhan, Archana; Layton, Alice C; Vishnivetskaya, Tatiana A; Williams, Daniel; Pfiffner, Susan M; Rekepalli, Bhanu; Stackhouse, Brandon; Lau, Maggie C Y; Phelps, Tommy J; Mykytczuk, Nadia; Ronholm, Jennifer; Whyte, Lyle; Onstott, Tullis C; Sayler, Gary S

    2014-11-20

    Microbial release of greenhouse gases from thawing permafrost is a global concern. Seventy-six metagenomes were generated from low-soil-organic-carbon mineral cryosols from Axel Heiberg Island, Nunavut, Canada, during a controlled thawing experiment. Permafrost thawing resulted in an increase in anaerobic fermenters and sulfate-reducing bacteria but not methanogens. Copyright © 2014 Chauhan et al.

  11. The effect of repeated freeze-thaw cycles on human muscle tissue visualized by postmortem computed tomography (PMCT)

    NARCIS (Netherlands)

    Klop, Anthony C.; Vester, Marloes E. M.; Colman, Kerri L.; Ruijter, Jan M.; van Rijn, Rick R.; Oostra, Roelof-Jan

    2017-01-01

    The aim of this study was to determine whether effects of repetitive freeze-thaw cycles, with various thawing temperatures, on human muscle tissue can be quantified using postmortem computed tomography (PMCT) technology. An additional objective was to determine the preferred thawing temperature for

  12. A practical algorithm to estimate soil thawing onset with the soil moisture active passive (SMAP) data

    Science.gov (United States)

    Chen, X.; Liu, L.

    2016-12-01

    The Soil Moisture Active Passive (SMAP) satellite simultaneously collected active and passive microwave data at L-band from April to July, 2015. The L-band radiometer brightness temperature (TB) data are strongly sensitive to the change of soil moisture, therefore, can be used to estimate freeze/thaw state of soil. We applied an edge detection method to detect the onset of thawing based on the SMAP level-1C TB data. This method convolves the first derivative of the Gaussian function as a kernel with the TB time series. When thawing occurs, soil moisture increases abruptly and leads to a decrease in TB. Therefore, a primary thaw event can be identified when the convolved signal reaches a local minimum. Considering the noise of the radiometer data, not all local minimums correspond to a thaw event. Therefore, we further applied a filter based on a priori or in situ soil temperature observation to eliminate false events. We compared the TB-based estimates with in situ measurements of soil temperature, moisture, and snow depth from April to June from 5 SNOTEL sites in Alaska. Our results show that at 4 out of the 5 sites the estimated thawing onsets and in-situ data agree within 5 to 10 days. However, we found a distinct inconsistency of 41 days at the fifth site. One possible reason is the mismatch in spatial coverage: one pixel of SMAP radiometer data has a size of 36 km, within which different areas may have different freeze/thaw states. The SMAP radar backscatter coefficient (σ0) data are also very sensitive to soil moisture, and has finer spatial resolution of 1 km, making it more directly comparable with the in situ measurements. We applied a seasonal threshold method to estimate thawing onset based on this data. Firstly, we set a thaw onset based on the in situ soil temperature and moisture measurements at 5 cm depth. Then we averaged σ0 observations from April 14th to 7 days before the thaw onset to represent the frozen soil, and used the mean value from 7

  13. Effects of aging and freezing/thawing sequence on quality attributes of bovine and

    Directory of Open Access Journals (Sweden)

    Hyun-Wook Kim

    2017-02-01

    Full Text Available Objective The effects of aging and freezing/thawing sequence on color, physicochemical, and enzymatic characteristics of two beef muscles (Mm. gluteus medius, GM and biceps femoris, BF were evaluated. Methods Beef muscles at 3 d postmortem were assigned to four different combinations of aging and freezing/thawing sequence as follows; aging at 2°C for 3 wk (A3, never-frozen control, freezing at −28°C for 2 wk then thawing (F2, frozen/thawed-only, aging at 2°C for 3 wk, freezing at −28°C for 2 wk then thawing (A3F2, and freezing at −28°C for 2 wk, thawing then further aging at 2°C for 3 wk (F2A3. Results No significant interactions between different aging/freezing/thawing treatments and muscle type on all measurements were found. Postmortem aging, regardless of aging/freezing/thawing sequence, had no impact on color stability of frozen/thawed beef muscles (p<0.05. F2A3 resulted in higher purge loss than F2 and A3F2 treatments (p<0.05. A3F2 and F2A3 treatments resulted in lower shear force of beef muscles compared to F2 (p<0.05. Although there was no significant difference in glutathione peroxidase (GSH-Px activity, F2A3 had the highest β-N-acetyl glucominidase (BNAG activity in purge, but the lowest BNAG activity in muscle (p<0.05. GM muscle exhibited higher total color changes and purge loss, and lower GSH-Px activity than BF muscle. Conclusion The results from this present study indicate that different combinations of aging/freezing/thawing sequence would result in considerable impacts on meat quality attributes, particularly thaw/purge loss and tenderness. Developing a novel freezing strategy combined with postmortem aging will be beneficial for the food/meat industry to maximize its positive impacts on tenderness, while minimizing thaw/purge loss of frozen/thawed meat.

  14. Effects of Permafrost Thaw on Net Ecosystem Carbon Balance in a Subarctic Peatland

    Science.gov (United States)

    Wang, Z.; Roulet, N. T.; Moore, T. R.

    2014-12-01

    This research is to assess changes in net ecosystem carbon balance (NECB) with permafrost thaw in northern peatland: in particular how changes in C biogeochemistry influence NECB. Thawed transects associated with varying stages of permafrost thaw: from palsas with intact permafrost (P), through edge of palsa (EP), dry lawn (DL), wet lawn (WL), edge of thawed pond (ET), pond sedges (PS), to several thawed ponds (TP) in a subarctic peatland in northern Quebec were sampled in the snow free seasons of 2013 and 2014. The exchange of CO2 and CH4, vegetation, dissolved organic C (DOC) concentration and biodegradability, active layer depth, air and peat temperatures, water table depth (WT), pH, and conductivity were measured. Peat temperatures were quite similar among different locations, but the WT decreased significantly along the transect creating varied environmental conditions that supporting different plant communities. From dry to wet area, vegetation abundance and biomass showed reductions of shrubs and lichens, and increases of Sphagnum, grasses and sedges. Pore water pH increased from dry to wet area, and conductivity slightly decreased. Wet thaw area WL, ET and PS had relatively higher season gross ecosystem production (GEP) and higher season ecosystem respiration (ER), but relative similar net ecosystem CO2 exchange (NEE). Only TP had a significant higher positive season NEE. Palsa was the only CH4 sink, and quite high CH4 emissions were found after it thawed. CH4-C release significantly increased from dry to wet in thawed area, which even several times bigger than total C exchange in ET and PS. Generally, wet area had higher DOC concentration and higher DOC biodegradability indicated by lower SUVA254 (except PS which received great influence from pond). All components in the NECB (GEP, ER, CH4, DOC) increased significantly in magnitude from palsa to wet thawed area, and ecosystem C sink turned into source as palsa thawed into PS and TP. These results

  15. Cryopreserving turkey semen in straws and nitrogen vapour using DMSO or DMA: effects of cryoprotectant concentration, freezing rate and thawing rate on post-thaw semen quality.

    Science.gov (United States)

    Iaffaldano, N; Di Iorio, M; Miranda, M; Zaniboni, L; Manchisi, A; Cerolini, S

    2016-04-01

    1. This study was designed to identify a suitable protocol for freezing turkey semen in straws exposed to nitrogen vapour by examining the effects of dimethylacetamide (DMA) or dimethylsulfoxide (DMSO) as cryoprotectant (CPA), CPA concentration, freezing rate and thawing rate on in vitro post-thaw semen quality. 2. Pooled semen samples were diluted 1:1 (v:v) with a freezing extender composed of Tselutin diluent containing DMA or DMSO to give final concentrations of 8% or 18% DMA and 4% or 10% DMSO. The semen was packaged in 0.25 ml plastic straws and frozen at different heights above the liquid nitrogen (LN2) surface (1, 5 and 10 cm) for 10 min. Semen samples were thawed at 4°C for 5 min or at 50°C for 10 s. After thawing, sperm motility, viability and osmotic tolerance were determined. 3. Cryosurvival of turkey sperm was affected by DMSO concentration. Freezing rate affected the motility of sperm cryopreserved using both CPAs, while thawing rates showed an effect on the motility of sperm cryopreserved using DMA and on the viability of sperm cryopreserved using DMSO. Significant interactions between freezing rate × thawing rate on sperm viability in the DMA protocol were found. 4. The most effective freezing protocol was the use of 18% DMA or 10% DMSO with freezing 10 cm above the LN2 surface and a thawing temperature of 50°C. An efficient protocol for turkey semen would improve prospects for sperm cryobanks and the commercial use of frozen turkey semen.

  16. Recent developments in novel freezing and thawing technologies applied to foods.

    Science.gov (United States)

    Wu, Xiao-Fei; Zhang, Min; Adhikari, Benu; Sun, Jincai

    2017-11-22

    This article reviews the recent developments in novel freezing and thawing technologies applied to foods. These novel technologies improve the quality of frozen and thawed foods and are energy efficient. The novel technologies applied to freezing include pulsed electric field pre-treatment, ultra-low temperature, ultra-rapid freezing, ultra-high pressure and ultrasound. The novel technologies applied to thawing include ultra-high pressure, ultrasound, high voltage electrostatic field (HVEF), and radio frequency. Ultra-low temperature and ultra-rapid freezing promote the formation and uniform distribution of small ice crystals throughout frozen foods. Ultra-high pressure and ultrasound assisted freezing are non-thermal methods and shorten the freezing time and improve product quality. Ultra-high pressure and HVEF thawing generate high heat transfer rates and accelerate the thawing process. Ultrasound and radio frequency thawing can facilitate thawing process by volumetrically generating heat within frozen foods. It is anticipated that these novel technologies will be increasingly used in food industries in the future.

  17. Methane emissions proportional to permafrost carbon thawed in Arctic lakes since the 1950s

    Science.gov (United States)

    Walter Anthony, Katey; Daanen, Ronald; Anthony, Peter; Schneider von Deimling, Thomas; Ping, Chien-Lu; Chanton, Jeffrey P.; Grosse, Guido

    2016-09-01

    Permafrost thaw exposes previously frozen soil organic matter to microbial decomposition. This process generates methane and carbon dioxide, and thereby fuels a positive feedback process that leads to further warming and thaw. Despite widespread permafrost degradation during the past ~40 years, the degree to which permafrost thaw may be contributing to a feedback between warming and thaw in recent decades is not well understood. Radiocarbon evidence of modern emissions of ancient permafrost carbon is also sparse. Here we combine radiocarbon dating of lake bubble trace-gas methane (113 measurements) and soil organic carbon (289 measurements) for lakes in Alaska, Canada, Sweden and Siberia with numerical modelling of thaw and remote sensing of thermokarst shore expansion. Methane emissions from thermokarst areas of lakes that have expanded over the past 60 years were directly proportional to the mass of soil carbon inputs to the lakes from the erosion of thawing permafrost. Radiocarbon dating indicates that methane age from lakes is nearly identical to the age of permafrost soil carbon thawing around them. Based on this evidence of landscape-scale permafrost carbon feedback, we estimate that 0.2 to 2.5 Pg permafrost carbon was released as methane and carbon dioxide in thermokarst expansion zones of pan-Arctic lakes during the past 60 years.

  18. Pengaruh Metode Thawing terhadap Kualitas Semen Beku Sapi Bali, Sapi Madura dan Sapi PO

    Directory of Open Access Journals (Sweden)

    Muhammad Ade Salim

    2012-10-01

    Full Text Available Effect of thawing technique to quality frozen semen spermatozoa in bali, madura and PO cattle ABSTRACT. The experiment was conducted from November 2011 to January 2012 in BBIB Singosari. The study aims was to determine the effect of thawing techniques on the quality frozen bovine sperm Bali, Madura and PO cattle. This material used 90 frozen straw of three cattle from the three breed. The method is an experiment with three treatments and 10 replications for frozen to thawing in temperature water is 5 0C of duration 60 seconds, 15 0C duration 30 seconds and 37 0C duration 15 seconds. Variables observed in this study were sperm quality are motility, viability and abnormality. Data in percentage transformed in to arcus sinus were analyzed using Completely Randomized Block Design (CRBD with replication as blocks of 10x. The results showed the thawing at 37 0C duration 15 seconds to highly significant effect (P0,05. Breed cattle not significant effect to quality. It can be concluded that thawing techniques impact the motility and viability in frozen bovine semen spermatozoa Bali, Madura and PO cattle. Thawing using 37 0C temperature water with duration of 15 seconds is the best method to obtain the quality of spermatozoa post thawing frozen sperm.

  19. Cryopreserved human aortic root allografts arterial wall: Structural changes occurring during thawing.

    Directory of Open Access Journals (Sweden)

    Robert Novotny

    Full Text Available The aim of our experimental work was to assess morphological changes of arterial wall that arise during different thawing protocols of a cryopreserved human aortic root allograft (CHARA arterial wall.The experiment was performed on CHARAs. Two thawing protocols were tested: 1, CHARAs were thawed at a room temperature at +23°C; 2, CHARAs were placed directly into a water bath at +37°C.After fixation, all samples were washed in distilled water for 5 min, and dehydrated in a graded ethanol series (70, 85, 95, and 100% for 5 min at each level. The tissue samples were then immersed in 100% hexamethyldisilazane for 10 minutes and air dried in an exhaust hood at room temperature. Processed samples were mounted on stainless steel stubs, coated with gold.Thawing protocol 1: All 6 (100% samples showed loss of the endothelium and damage to the subendothelial layers with randomly dispersed circular defects and micro-fractures without smooth muscle cells contractions in the tunica media. Thawing protocol 2: All 6 (100% samples showed loss of endothelium from the luminal surface, longitudinal corrugations in the direction of blood flow caused by smooth muscle cells contractions in the tunica media with frequent fractures in the subendothelial layer.All the samples thawed at the room temperature showed smaller structural damage to the CHARA arterial wall with no smooth muscle cell contraction in tunica media when compared to the samples thawed in a water bath.

  20. Rapid carbon loss and slow recovery following permafrost thaw in boreal peatlands.

    Science.gov (United States)

    Jones, Miriam C; Harden, Jennifer; O'Donnell, Jonathan; Manies, Kristen; Jorgenson, Torre; Treat, Claire; Ewing, Stephanie

    2017-03-01

    Permafrost peatlands store one-third of the total carbon (C) in the atmosphere and are increasingly vulnerable to thaw as high-latitude temperatures warm. Large uncertainties remain about C dynamics following permafrost thaw in boreal peatlands. We used a chronosequence approach to measure C stocks in forested permafrost plateaus (forest) and thawed permafrost bogs, ranging in thaw age from young (100 years) from two interior Alaska chronosequences. Permafrost originally aggraded simultaneously with peat accumulation (syngenetic permafrost) at both sites. We found that upon thaw, C loss of the forest peat C is equivalent to ~30% of the initial forest C stock and is directly proportional to the prethaw C stocks. Our model results indicate that permafrost thaw turned these peatlands into net C sources to the atmosphere for a decade following thaw, after which post-thaw bog peat accumulation returned sites to net C sinks. It can take multiple centuries to millennia for a site to recover its prethaw C stocks; the amount of time needed for them to regain their prethaw C stocks is governed by the amount of C that accumulated prior to thaw. Consequently, these findings show that older peatlands will take longer to recover prethaw C stocks, whereas younger peatlands will exceed prethaw stocks in a matter of centuries. We conclude that the loss of sporadic and discontinuous permafrost by 2100 could result in a loss of up to 24 Pg of deep C from permafrost peatlands. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

  1. Evaluation of Serial Thawing-Refreezing on Human Spermatozoa Resistance Using Cryovials and Straws

    Directory of Open Access Journals (Sweden)

    Fatemeh Ghasemian

    2012-01-01

    Full Text Available Background: We designed this study to detect the cryoinjury rate on human sperm after serialfreezing and thawing, taking into consideration the effects of using cryovials and straws.Materials and Methods: In this experimental study, semen specimens obtained from 15 subjectswere divided into normozoospermic and oligozoospermic groups. Each of the normozoospermicand oligozoo spermic semen specimens were additionally divided into two groups: i. washed andii. unwashed. Specimens were repeatedly freeze-thawed by using cryovials and straws with thefast liquid nitrogen vapor method, until no motile sperm remained. Sperm motility, recovery, andmorphology rate were then determined after thawing, and compared between the groups whiletaking into consideration the effects of using cryovials and straws.Results: Motile spermatozoa were observed in all normozoospermic samples up to thaw 6 with bothcryovials and straws while in oligozoospermic specimens up to thaw 4 (straw and thaw 3 (cryovialin the freeze-thawing cycle. Normozoospermic sample analysis showed no significant difference inmorphology rate. There was a significant increase in motility and recovery percentages for washedsamples, which was observed with straws in compared to the unwashed groups. Oligozoospermicsample analysis indicated a significant increase in motility, recovery (p<0.01, and morphology(p<0.001 rates in washed specimens compared to unwashed specimens using straws. Theimportance of washing sperm was obvious for oligozoospermic specimens.Conclusion: Normozoospermic sperm resisted freezing longer than oligozoospermic sperm. Use ofstraws and cryovials made significant differences in motility, recovery, and morphology of sperm ineach thaw. This difference was slightly higher for oligozoospermic specimens. Results indicated thatthe percentage of motility was higher for washed normozoospermic specimens in each thaw whenstraws were used, whereas the percentage of motility, recovery, and

  2. Influence of extender, freezing rate, and thawing rate on post-thaw motility, viability and morphology of coyote (Canis latrans) spermatozoa.

    Science.gov (United States)

    Minter, Larry J; Deliberto, Thomas J

    2005-12-01

    The objective of this study was to examine the post-thaw effects of three cryoprotective extenders (Tris-fructose-citric acid extender, Tris-glucose-citric acid extender, and lactose extender), three linear freezing rates (-1, -6, and -20 degrees C/min), and three thawing rates (37 degrees C water bath for 120s, 60 degrees C water bath for 30s, and 70 degrees C water bath for 8s) on coyote spermatozoa. After thawing, the findings supported that cryopreservation of coyote (Canis latrans) spermatozoa frozen at a moderate freezing rate (-6 degrees C/min), in either a Tris-fructose or Tris-glucose extender, and thawed at a slow rate (37 degrees C water bath for 120s) or moderate rate (60 degrees C water bath for 30s), resulted in a more vigorous post-thaw motility (range, 57.5-44.0%) and viability (range, 64-49.6%) with the least amount of morphological and acrosomal abnormalities.

  3. the effect of pellet volume, dilution rates prefreezing and at thawing

    African Journals Online (AJOL)

    and of thawing temperature on the fr~ezingand thawing velocities and ... of thawed semen were incubated for all pellet volumes. (e.g. 20 x 0 ..... ( bcenWe of gcnmbzu wiflt twttul uwtu. ) Thrwi4 rm. Pmrrul? (oc). IXrrtio ntc. $ thrbg hlb't rohm. (d). XcDr. 0p3 o,l5. 0J0 o,60. 37. 42. 47 s2 l:0r l:l l:2 l:3 l:4. 8,1. 265. 4r3. 439. 17,l. 2f.rl.

  4. Analyzing Factors Affecting the Success Rate of Frozen–Thawed Embryos

    OpenAIRE

    Lahav-Baratz, S.; Koifman, M.; Shiloh, H.; Ishai, D.; Wiener-Megnazi, Z.; Dirnfeld, M.

    2003-01-01

    Purpose: In recent years the infertile population applying for IVF treatments was changed and so the indications for performing intracellular sperm injection (ICSI). The aim of this study was to analyze predicting factors of our thawing cycles.

  5. Northern Hemisphere EASE-Grid Annual Freezing and Thawing Indices, 1901 - 2002, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains annual freezing and thawing indices for each year from 1901 to 2002 on the 25 km resolution Equal-Area Scalable Earth Grid (EASE-Grid). Annual...

  6. Complete follicular development and recovery of ovarian function of frozen-thawed, autotransplanted caprine ovarian cortex

    NARCIS (Netherlands)

    Santos, Regiane R; Knijn, Hiemke M|info:eu-repo/dai/nl/25878931X; Vos, Peter L A M|info:eu-repo/dai/nl/125591233; Oei, Christine H Y; van Loon, Thijs|info:eu-repo/dai/nl/304834610; Colenbrander, Ben; Gadella, Bart M|info:eu-repo/dai/nl/115389873; van den Hurk, Rob; Roelen, Bernard A J|info:eu-repo/dai/nl/109291859

    Frozen-thawed ovarian cortical fragments (1 mm(3)) were autotransplanted to the uterus of completely ovariectomized goats. The grafts developed preovulatory follicles, accompanied by estrous behavior and a rise in plasma E(2) levels, demonstrating successful cryopreservation and transplantation.

  7. MEaSUREs Global Record of Daily Landscape Freeze/Thaw Status

    Data.gov (United States)

    National Aeronautics and Space Administration — The MEaSUREs Global Record of Daily Landscape Freeze/Thaw Status, Version 01 data set is derived from the Defense Meteorological Satellite Program (DMSP) satellite...

  8. Comparison Study of Three Common Technologies for Freezing-Thawing Measurement

    Directory of Open Access Journals (Sweden)

    Xinbao Yu

    2010-01-01

    Full Text Available This paper describes a comparison study on three different technologies (i.e., thermocouple, electrical resistivity probe and Time Domain Reflectometry (TDR that are commonly used for frost measurement. Specially, the paper developed an analyses procedure to estimate the freezing-thawing status based on the dielectric properties of freezing soil. Experiments were conducted where the data of temperature, electrical resistivity, and dielectric constant were simultaneously monitored during the freezing/thawing process. The comparison uncovered the advantages and limitations of these technologies for frost measurement. The experimental results indicated that TDR measured soil dielectric constant clearly indicates the different stages of the freezing/thawing process. Analyses method was developed to determine not only the onset of freezing or thawing, but also the extent of their development. This is a major advantage of TDR over other technologies.

  9. Resumption of mitosis in frozen-thawed embryos is not related to the chromosomal constitution

    DEFF Research Database (Denmark)

    Agerholm, Inge E; Kølvrå, Steen; Crüger, Dorthe G

    2007-01-01

    OBJECTIVE: To study the relation between the resumption of mitosis after thaw and chromosomal constitution in frozen-thawed embryos. In addition, to evaluate the correlation among the three parameters of resumption of mitosis after thaw, postthaw blastomere loss, and multinucleation. DESIGN: Frozen......(S): Forty IVF and/or intracytoplasmic sperm injection patients. INTERVENTION(S): Embryo thawing, morphological evaluation, and fluorescence in situ hybridization analysis for aneuploidy screening. MAIN OUTCOME MEASURE(S): Resumption of mitosis, blastomere loss, multinucleation, and chromosome enumeration....... RESULT(S): No difference was observed in the chromosomal constitution of embryos with and without resumption of mitosis. Neither was the postthaw blastomere loss connected to the chromosomal constitution. The resumption of mitosis was not associated with postthaw loss of blastomeres...

  10. Brief and vigorous N2O production by soil at spring thaw

    DEFF Research Database (Denmark)

    Christensen, Søren; Tiedje, James M.

    1990-01-01

    measurements; nitrate was added in excess. This effect could be reproduced in the laboratory: thawing soil cores at controlled temperature, nitrate and moisture yielded a large flush of N2O compared to an unfrozen control. The results indicate the importance of microbial N2O production during thaw for total......In an acid sandy loam soil (pH 3.8), field production of N2O was two orders of magnitude higher at thaw in the spring than at any time during the rest of the year. Soil thaw in midwinter did not result in any increase in N2O flux. Soil water content remained at, or above field capacity during...

  11. Annual Thaw Depths and Water Depths in Tanana Flats, Alaska, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — Thaw depths and water depths were monitored at 1 m to 2 m intervals along a 255-m transect across an area of discontinuous and degrading permafrost on the Tanana...

  12. Arctic EASE-Grid Freeze and Thaw Depths, 1901 - 2002, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains mean, median, minimum and maximum freeze and thaw depths for each year from 1901 to 2002 on the 25 km resolution Equal-Area Scalable Earth...

  13. A Global Database of Gas Fluxes from Soils after Rewetting or Thawing, Version 1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This database contains information compiled from published studies on gas flux from soil following rewetting or thawing. The resulting database includes 222 field...

  14. Failure of cement hydrates: freeze-thaw and fracture

    Science.gov (United States)

    Ioannidou, Katerina; Del Gado, Emanuela; Ulm, Franz-Josef; Pellenq, Roland

    Mechanical and viscoelastic behavior of concrete crucially depends on cement hydrates, the ``glue'' of cement. Even more than the atomistic structure, the mesoscale amorphous texture of cement hydrates over hundreds of nanometers plays a crucial role for material properties. We use simulations that combine information of the nano-scale building units of cement hydrates and on their effective interactions, obtained from atomistic simulations and experiments, into a statistical physics framework for aggregating nanoparticles.Our mesoscale model was able to reconcile different experimental results ranging from small-angle neutron scattering, SEM, adsorption/desorption of N2, and water to nanoindentation and gain the new fundamental insights into the microscopic origin of the properties measured. Our results suggest that heterogeneities developed during the early stages of hydration persist in the structure of C-S-H, impacting the rheological and mechanical performance of the hardened cement paste. In this talk I discuss recent investigation on failure mechanism at the mesoscale of hardened cement paste such as freeze-thaw and fracture. Using correlations between local volume fractions and local stress we provide a link between structural and mechanical heterogeneities during the failure mechanisms.

  15. Physical Model and Mesoscale Simulation of Mortar and Concrete Deformations under Freeze–Thaw Cycles

    OpenAIRE

    Gong, Fuyuan; Sicat, Evdon; Wang, Yi; Ueda, Tamon; Zhang, Dawei

    2014-01-01

    The degradation of concrete material under multiple freeze–thaw cycles is an important issue for structures in cold and wet regions. This paper proposed a physical and mechanical model to explain the deformation behavior observed in previous experiments, from internal pressure calculation to mesoscale simulation, and for both closed and open freeze–thaw tests. Three kinds of internal pressures are considered in this study: hydraulic pressure due to ice volume expansion, crystallization pressu...

  16. Nitrogen availability increases in a tundra ecosystem during five years of experimental permafrost thaw.

    Science.gov (United States)

    Salmon, Verity G; Soucy, Patrick; Mauritz, Marguerite; Celis, Gerardo; Natali, Susan M; Mack, Michelle C; Schuur, Edward A G

    2016-05-01

    Perennially frozen soil in high latitude ecosystems (permafrost) currently stores 1330-1580 Pg of carbon (C). As these ecosystems warm, the thaw and decomposition of permafrost is expected to release large amounts of C to the atmosphere. Fortunately, losses from the permafrost C pool will be partially offset by increased plant productivity. The degree to which plants are able to sequester C, however, will be determined by changing nitrogen (N) availability in these thawing soil profiles. N availability currently limits plant productivity in tundra ecosystems but plant access to N is expected improve as decomposition increases in speed and extends to deeper soil horizons. To evaluate the relationship between permafrost thaw and N availability, we monitored N cycling during 5 years of experimentally induced permafrost thaw at the Carbon in Permafrost Experimental Heating Research (CiPEHR) project. Inorganic N availability increased significantly in response to deeper thaw and greater soil moisture induced by Soil warming. This treatment also prompted a 23% increase in aboveground biomass and a 49% increase in foliar N pools. The sedge Eriophorum vaginatum responded most strongly to warming: this species explained 91% of the change in aboveground biomass during the 5 year period. Air warming had little impact when applied alone, but when applied in combination with Soil warming, growing season soil inorganic N availability was significantly reduced. These results demonstrate that there is a strong positive relationship between the depth of permafrost thaw and N availability in tundra ecosystems but that this relationship can be diminished by interactions between increased thaw, warmer air temperatures, and higher levels of soil moisture. Within 5 years of permafrost thaw, plants actively incorporate newly available N into biomass but C storage in live vascular plant biomass is unlikely to be greater than losses from deep soil C pools. © 2015 John Wiley & Sons Ltd.

  17. Colloid-facilitated mobilization of metals by freeze-thaw cycles.

    Science.gov (United States)

    Mohanty, Sanjay K; Saiers, James E; Ryan, Joseph N

    2014-01-21

    The potential of freeze-thaw cycles to release colloids and colloid-associated contaminants into water is unknown. We examined the effect of freeze-thaw cycles on the mobilization of cesium and strontium in association with colloids in intact cores of a fractured soil, where preferential flow paths are prevalent. Two intact cores were contaminated with cesium and strontium. To mobilize colloids and metal cations sequestered in the soil cores, each core was subjected to 10 intermittent wetting events separated by 66 h pauses. During the first five pauses, the cores were dried at room temperature, and during last five pauses, the cores were subjected to 42 h of freezing followed by 24 h of thawing. In comparison to drying, freeze-thaw cycles created additional preferential flow paths through which colloids, cesium, and strontium were mobilized. The wetting events following freeze-thaw intervals mobilized about twice as many colloids as wetting events following drying at room temperature. Successive wetting events following 66 h of drying mobilized similar amounts of colloids; in contrast, successive wetting events after 66 h of freeze-thaw intervals mobilized greater amounts of colloids than the previous one. Drying and freeze-thaw treatments, respectively, increased and decreased the dissolved cesium and strontium, but both treatments increased the colloidal cesium and strontium. Overall, the freeze-thaw cycles increased the mobilization of metal contaminants primarily in association with colloids through preferential flow paths. These findings suggest that the mobilization of colloid and colloid-associated contaminants could increase when temperature variations occur around the freezing point of water. Thus, climate extremes have the potential to mobilize contaminants that have been sequestered in the vadose zone for decades.

  18. Metagenomic analysis of a permafrost microbial community reveals a rapid response to thaw

    Science.gov (United States)

    MacKelprang, R.; Waldrop, M.P.; Deangelis, K.M.; David, M.M.; Chavarria, K.L.; Blazewicz, S.J.; Rubin, E.M.; Jansson, J.K.

    2011-01-01

    Permafrost contains an estimated 1672????????Pg carbon (C), an amount roughly equivalent to the total currently contained within land plants and the atmosphere. This reservoir of C is vulnerable to decomposition as rising global temperatures cause the permafrost to thaw. During thaw, trapped organic matter may become more accessible for microbial degradation and result in greenhouse gas emissions. Despite recent advances in the use of molecular tools to study permafrost microbial communities, their response to thaw remains unclear. Here we use deep metagenomic sequencing to determine the impact of thaw on microbial phylogenetic and functional genes, and relate these data to measurements of methane emissions. Metagenomics, the direct sequencing of DNA from the environment, allows the examination of whole biochemical pathways and associated processes, as opposed to individual pieces of the metabolic puzzle. Our metagenome analyses reveal that during transition from a frozen to a thawed state there are rapid shifts in many microbial, phylogenetic and functional gene abundances and pathways. After one week of incubation at 5 ??C, permafrost metagenomes converge to be more similar to each other than while they are frozen. We find that multiple genes involved in cycling of C and nitrogen shift rapidly during thaw. We also construct the first draft genome from a complex soil metagenome, which corresponds to a novel methanogen. Methane previously accumulated in permafrost is released during thaw and subsequently consumed by methanotrophic bacteria. Together these data point towards the importance of rapid cycling of methane and nitrogen in thawing permafrost. ?? 2011 Macmillan Publishers Limited. All rights reserved.

  19. Products and stability of phosphate reactions with lead under freeze-thaw cycling in simple systems

    Energy Technology Data Exchange (ETDEWEB)

    Hafsteinsdottir, Erla G., E-mail: erla.hafsteinsdottir@gmail.com [Department of Environment and Geography, Macquarie University, NSW 2109 (Australia); White, Duanne A., E-mail: duanne.white@mq.edu.au [Department of Environment and Geography, Macquarie University, NSW 2109 (Australia); Gore, Damian B., E-mail: damian.gore@mq.edu.au [Department of Environment and Geography, Macquarie University, NSW 2109 (Australia); Stark, Scott C., E-mail: scott.stark@aad.gov.au [Environmental Protection and Change, Australian Antarctic Division, Department of Sustainability, Environment, Water, Population and Communities, Tasmania 7050 (Australia)

    2011-12-15

    Orthophosphate fixation of metal contaminated soils in environments that undergo freeze-thaw cycles is understudied. Freeze-thaw cycling potentially influences the reaction rate, mineral chemical stability and physical breakdown of particles during fixation. This study determines what products form when phosphate (triple superphosphate [Ca(H{sub 2}PO{sub 4}){sub 2}] or sodium phosphate [Na{sub 3}PO{sub 4}]) reacts with lead (PbSO{sub 4} or PbCl{sub 2}) in simple chemical systems in vitro, and assesses potential changes in formation during freeze-thaw cycles. Systems were subjected to multiple freeze-thaw cycles from +10 deg. C to -20 deg. C and then analysed by X-ray diffractometry. Pyromorphite formed in all systems and was stable over multiple freeze-thaw cycles. Low temperature lead orthophosphate reaction efficiency varied according to both phosphate and lead source; the most time-efficient pyromorphite formation was observed when PbSO{sub 4} and Na{sub 3}PO{sub 4} were present together. These findings have implications for the manner in which metal contaminated materials in freezing ground can be treated with phosphate. - Highlights: > Formation of lead phosphate products in cold environments is identified. > Potential change in formation during freeze-thaw cycling is assessed. > Lead phosphate reaction efficiency varies according to phosphate and lead source. > Pyromorphite formation is stable during 240 freeze-thaw cycles. - Pyromorphite, formed from Pb phosphate fixation, is stable during multiple freeze-thaw cycles but the efficiency of the fixation depends on the phosphate source and the type of Pb mineral.

  20. The transcriptional response of microbial communities in thawing Alaskan permafrost soils.

    Science.gov (United States)

    Coolen, Marco J L; Orsi, William D

    2015-01-01

    Thawing of permafrost soils is expected to stimulate microbial decomposition and respiration of sequestered carbon. This could, in turn, increase atmospheric concentrations of greenhouse gasses, such as carbon dioxide and methane, and create a positive feedback to climate warming. Recent metagenomic studies suggest that permafrost has a large metabolic potential for carbon processing, including pathways for fermentation and methanogenesis. Here, we performed a pilot study using ultrahigh throughput Illumina HiSeq sequencing of reverse transcribed messenger RNA to obtain a detailed overview of active metabolic pathways and responsible organisms in up to 70 cm deep permafrost soils at a moist acidic tundra location in Arctic Alaska. The transcriptional response of the permafrost microbial community was compared before and after 11 days of thaw. In general, the transcriptional profile under frozen conditions suggests a dominance of stress responses, survival strategies, and maintenance processes, whereas upon thaw a rapid enzymatic response to decomposing soil organic matter (SOM) was observed. Bacteroidetes, Firmicutes, ascomycete fungi, and methanogens were responsible for largest transcriptional response upon thaw. Transcripts indicative of heterotrophic methanogenic pathways utilizing acetate, methanol, and methylamine were found predominantly in the permafrost table after thaw. Furthermore, transcripts involved in acetogenesis were expressed exclusively after thaw suggesting that acetogenic bacteria are a potential source of acetate for acetoclastic methanogenesis in freshly thawed permafrost. Metatranscriptomics is shown here to be a useful approach for inferring the activity of permafrost microbes that has potential to improve our understanding of permafrost SOM bioavailability and biogeochemical mechanisms contributing to greenhouse gas emissions as a result of permafrost thaw.

  1. The transcriptional response of microbial communities in thawing Alaskan permafrost soils

    Directory of Open Access Journals (Sweden)

    M J L Coolen

    2015-03-01

    Full Text Available Thawing of permafrost soils is expected to stimulate microbial decomposition and respiration of sequestered carbon. This could, in turn, increase atmospheric concentrations of greenhouse gases, such as carbon dioxide and methane, and create a positive feedback to climate warming. Recent metagenomic studies suggest that permafrost has a large metabolic potential for carbon processing, including pathways for fermentation and methanogenesis. Here, we performed a pilot study using ultrahigh throughput Illumina HiSeq sequencing of reverse transcribed messenger RNA to obtain a detailed overview of active metabolic pathways and responsible organisms in up to 70 cm deep permafrost soils at a moist acidic tundra location in Arctic Alaska. The transcriptional response of the permafrost microbial community was compared before and after eleven days of thaw. In general, the transcriptional profile under frozen conditions suggests a dominance of stress responses, survival strategies, and maintenance processes, whereas upon thaw a rapid enzymatic response to decomposing soil organic matter (SOM was observed. Bacteroidetes, Firmicutes, ascomycete fungi, and methanogens were responsible for largest transcriptional response upon thaw. Transcripts indicative of heterotrophic methanogenic pathways utilizing acetate, methanol, and methylamine were found predominantly in the permafrost table after thaw. Furthermore, transcripts involved in acetogenesis were expressed exclusively after thaw suggesting that acetogenic bacteria are a potential source of acetate for acetoclastic methanogenesis in freshly thawed permafrost. Metatranscriptomics is shown here to be a useful approach for inferring the activity of permafrost microbes that has potential to improve our understanding of permafrost SOM bioavailability and biogeochemical mechanisms contributing to greenhouse gas emissions as a result of permafrost thaw.

  2. SLAPex-Initial Results from a Soil Freeze-Thaw Airborne Campaign

    Science.gov (United States)

    Kim, E. J.

    2016-12-01

    The SLAPex Freeze/Thaw airborne campaign took place in early November, 2015, near Carman, Manitoba, Canada (near Winnipeg). NASA Goddard's Scanning L-band Active Passive (SLAP) sensor—an airborne simulator of the Soil Moisture Active Passive (SMAP) satellite mission—made 11 flights on the NASA Langley B200 aircraft to observe frozen and thawed soil conditions. Detailed ground truth was collected by a joint US-Canadian team. Future soil moisture satellite missions are expected to include soil freeze/thaw products, just as SMAP does. The loss of the radar on SMAP means that airborne radar-radiometer observations like those from SLAPex freeze/thaw are very unique assets for freeze/thaw algorithm development. SLAP freeze/thaw airborne observations are also directly applicable to the science interests of NASA's Arctic-Boreal Vulnerability Experiment (ABoVE) project. SLAP has both passive (radiometer) and active (radar) microwave L-band imaging capabilities. The radiometer observes at 1.4 GHz using duplicate front end hardware from the SMAP satellite radiometer. It also includes a duplicate of the digital backend development unit for SMAP, thus the novel Radio Frequency Interference (RFI) detection and mitigation features and algorithms for SMAP are duplicated with very high fidelity in SLAP. The digital backend provides 4-Stokes polarization capability. The real-aperture radar operates in the 1215-1300 MHz band with quad-pol capability. Radar and radiometer share one antenna. This paper will present flight data, imagery, and comparisons with ground truth with respect to frozen or thawed state, soil moisture, and brightness temperature (comparison with ground-based radiometers). The high sensitivity of the The passive and active signatures seen in the SLAP observations indicates that microwave signatures of frozen vs. thawed soil can yield information on the controlling processes and ramifications for the water, energy, and carbon cycles

  3. Geophysical imaging and thermal modeling of subsurface morphology and thaw evolution of discontinuous permafrost

    Science.gov (United States)

    McClymont, Alastair F.; Hayashi, Masaki; Bentley, Laurence R.; Christensen, Brendan S.

    2013-09-01

    our current understanding of permafrost thaw in subarctic regions in response to rising air temperatures, little is known about the subsurface geometry and distribution of discontinuous permafrost bodies in peat-covered, wetland-dominated terrains and their responses to rising temperature. Using electrical resistivity tomography, ground-penetrating radar profiling, and thermal-conduction modeling, we show how the land cover distributions influence thawing of discontinuous permafrost at a study site in the Northwest Territories, Canada. Permafrost bodies in this region occur under forested peat plateaus and have thicknesses of 5-13 m. Our geophysical data reveal different stages of thaw resulting from disturbances within the active layer: from widening and deepening of differential thaw features under small frost-table depressions to complete thaw of permafrost under an isolated bog. By using two-dimensional geometric constraints derived from our geophysics profiles and meteorological data, we model seasonal and interannual changes to permafrost distribution in response to contemporary climatic conditions and changes in land cover. Modeling results show that in this environment (1) differences in land cover have a strong influence on subsurface thermal gradients such that lateral thaw dominates over vertical thaw and (2) in accordance with field observations, thaw-induced subsidence and flooding at the lateral margins of peat plateaus represents a positive feedback that leads to enhanced warming along the margins of peat plateaus and subsequent lateral heat conduction. Based on our analysis, we suggest that subsurface energy transfer processes (and feedbacks) at scales of 1-100 m have a strong influence on overall permafrost degradation rates at much larger scales.

  4. Computer forecasting of the soil water infiltration parameters in seasonal freezing and thawing periods

    National Research Council Canada - National Science Library

    Fan, Guisheng; Han, Yonghong; Ma, Danni

    2013-01-01

    ..., most research on soil moisture infiltration during freezing and thawing periods have been focused on the water loss and soil erosion caused by snow melting  [1–3] , the soil swelling from soil frozen-in and the change of moisture and salinity  [4] , the influence factors and mechanism of moisture infiltration into freezing and thawing soils  [5–9] and...

  5. STUDY ON TEMPERATURE DISTRIBUTION DUE TO FREEZING AND THAWING AT THE FENGMAN CONCRETE GRAVITY DAM

    Directory of Open Access Journals (Sweden)

    He Yu

    2011-01-01

    Full Text Available Freezing and thawing damage is one of the major problems of the Fengman concrete dam. Based on the temperature records of the dam, appropriate heat transfer boundary conditions in the dam body are suggested. A three-dimensional finite element model is used to determine annual variation of temperature field of the dam as a case study. The deterioration problem of concrete dam owing to freezing and thawing effect is investigated.

  6. Degradation potentials of dissolved organic carbon (DOC) from thawed permafrost peat

    Science.gov (United States)

    Panneer Selvam, Balathandayuthabani; Lapierre, Jean-François; Guillemette, Francois; Voigt, Carolina; Lamprecht, Richard E.; Biasi, Christina; Christensen, Torben R.; Martikainen, Pertti J.; Berggren, Martin

    2017-04-01

    Global warming can substantially affect the export of dissolved organic carbon (DOC) from peat-permafrost to aquatic systems. The direct degradability of such peat-derived DOC, however, is poorly constrained because previous permafrost thaw studies have mainly addressed mineral soil catchments or DOC pools that have already been processed in surface waters. We incubated peat cores from a palsa mire to compare an active layer and an experimentally thawed permafrost layer with regard to DOC composition and degradation potentials of pore water DOC. Our results show that DOC from the thawed permafrost layer had high initial degradation potentials compared with DOC from the active layer. In fact, the DOC that showed the highest bio- and photo-degradability, respectively, originated in the thawed permafrost layer. Our study sheds new light on the DOC composition of peat-permafrost directly upon thaw and suggests that past estimates of carbon-dioxide emissions from thawed peat permafrost may be biased as they have overlooked the initial mineralization potential of the exported DOC.

  7. Cryoprotectant Production in Freeze-Tolerant Wood Frogs Is Augmented by Multiple Freeze-Thaw Cycles.

    Science.gov (United States)

    Larson, Don J; Barnes, Brian M

    2016-01-01

    Ice nucleation across the skin of wood frogs (Lithobates sylvaticus) rapidly induces endogenous production of glucose, a cryoprotectant necessary for freeze tolerance. In laboratory studies of freeze tolerance, wood frogs are cooled slowly, often at -0.05°C h(-1), to facilitate high cryoprotectant production and survival. Under natural conditions in Alaska, however, wood frogs accumulate maximal tissue glucose concentrations while cooling at much faster rates, -0.35° to -1.6°C h(-1), and in addition undergo multiple successive freeze-thaw cycles before remaining frozen for the winter. We examined whether simulating these ecologically relevant cooling rates and repeated freeze-thaw events in captive wood frogs results in the high glucose concentrations found in naturally frozen wood frogs. We found that over successive freezing and thawing events, glucose concentrations increased stepwise in all measured tissues. Short thawing periods did not result in a statistically significant decline of glucose concentrations. Wood frogs that experienced three freeze-thaw events had fresh weight glucose concentrations that approached values found in tissues of wood frogs frozen in natural conditions. Laboratory wood frogs survive frozen for 2 mo, while wood frogs frozen under natural conditions survive frozen for up to 7 mo at temperatures below -18°C. We hypothesize that repeated freeze-thaw cycles with rapid cooling and warming rates allow for greater survival in Alaskan wood frogs through enhanced cryoprotectant production.

  8. Thaw bulb dimensions determined using electrical imaging across thermokarst lakes, Seward Peninsula, Alaska

    Science.gov (United States)

    Nolan, J. T.; Slater, L. D.; Parsekian, A.; Plug, L. J.; Grosse, G.; Walter Anthony, K. M.

    2009-12-01

    Geophysical imaging of thaw bulb dimensions underlying thermokarst lakes may provide data required to validate models for thaw bulb evolution and to quantify availability of previously frozen soil carbon to atmospheric emission. Direct measurements by drilling are costly in remote arctic regions and are limited by poor spatial resolution. We report the results of an experiment to test the use of electrical resistivity imaging for determining thaw bulb dimensions of thermokarst lakes on the Seward Peninsula, Alaska. Continuous resistivity measurements were collected using a floating array of electrodes pulled by a motorized inflatable boat. The inversion of the resistivity data was conducted using a one dimensional laterally constrained inversion routine that solves for thickness and resistivity based on three layer model. Since the water layer is partly constrained in terms of thickness (from depth sounder measurements) and resistivity (from measurements made with a conductance probe), and the thaw bulb and permafrost resistivity are known from coring, the only totally unconstrained parameter is the thickness of the thaw bulb sediments. This overdetermined inverse problem yields a high degree of confidence in the resulting model, as evident from low model residuals and parameter covariance analysis. Results from this experiment show that electrical resistivity imaging is a relatively low cost method for determining the thaw bulb dimensions along a laterally continuous survey line.

  9. Frozen-thawed rhinoceros sperm exhibit DNA damage shortly after thawing when assessed by the sperm chromatin dispersion assay.

    Science.gov (United States)

    Portas, T; Johnston, S D; Hermes, R; Arroyo, F; López-Fernadez, C; Bryant, B; Hildebrandt, T B; Göritz, F; Gosalvez, J

    2009-09-15

    This study reports on the successful validation (via in situ nick translation and neutral comet assay) of the equine Sperm-Halomax kit as an appropriate methodology for the assessment of sperm DNA fragmentation in three species of rhinoceros. Rhinoceros sperm nuclei with fragmented DNA (validated using in situ nick translation) were evident as large halos with dispersed DNA fragments, whereas those with nonfragmented DNA displayed small halos of nondispersed DNA within the microgel. There was a high correlation (r) of 0.974 (R(2) value=0.949; PSperm Chromatin Dispersion test (SCDt) and the neutral comet assay. Application of the SCDt to determine the DNA fragmentation dynamics of rhinoceros (n=6) sperm frozen in liquid nitrogen vapor and incubated postthaw at 37 degrees C for up to 48 h to mimic in vitro conditions in the female reproductive tract, revealed an increase (P=0.001) in DNA damage, as soon as 4h after the start of incubation. Linear regression equations were calculated for all six rhinoceroses over the first 6h of incubation and revealed individual animal variation. Freshly collected and incubated (37 degrees C) rhinoceros (n=3) sperm had no increase in the basal level of DNA fragmentation for up to 48 h, indicating that the cryopreservation of rhinoceros sperm in liquid nitrogen vapor, as used in this study, appeared to result in freeze-thaw DNA damage.

  10. Freezing/Thawing without Cryoprotectant Damages Native but not Decellularized Porcine Renal Tissue.

    Science.gov (United States)

    Poornejad, Nafiseh; Frost, Timothy S; Scott, Daniel R; Elton, Brinden B; Reynolds, Paul R; Roeder, Beverly L; Cook, Alonzo D

    2015-01-01

    Whole organ decellularization of porcine renal tissue and recellularization with a patient's own cells would potentially overcome immunorejection, which is one of the most significant problems with allogeneic kidney transplantation. However, there are obstacles to achieving this goal, including preservation of the decellularized extracellular matrix (ECM), identifying the proper cell types, and repopulating the ECM before transplantation. Freezing biological tissue is the best option to avoid spoilage; however, it may damage the structure of the tissue or disrupt cellular membranes through ice crystal formation. Cryoprotectants have been used to repress ice formation during freezing, although cell toxicity can still occur. The effect of freezing/thawing on native (n = 10) and decellularized (n = 10) whole porcine kidneys was studied without using cryoprotectants. Results showed that the elastic modulus of native kidneys was reduced by a factor of 22 (P freezing/thawing or decellularization, while the elastic modulus for decellularized ECM was essentially unchanged by the freezing/thawing process (p = 0.0636). Arterial pressure, representative of structural integrity, was also reduced by a factor of 52 (P freezing/thawing for native kidneys, compared to a factor of 43 (P freezing/thawing decellularized structures. Both freezing/thawing and decellularization reduced stiffness, but the reductions were not additive. Investigation of the microstructure of frozen/thawed native and decellularized renal tissues showed increased porosity due to cell removal and ice crystal formation. Orcein and Sirius staining showed partial damage to elastic and collagen fibers after freezing/thawing. It was concluded that cellular damage and removal was more responsible for reducing stiffness than fibril destruction. Cell viability and growth were demonstrated on decellularized frozen/thawed and non-frozen samples using human renal cortical tubular epithelial (RCTE) cells over 12 d. No

  11. The effect of permafrost thaw on short- and long-term carbon accumulation in permafrost mires

    Science.gov (United States)

    Olid, Carolina; Klaminder, Jonatan; Monteux, Sylvain; Johansson, Margareta; Dorrepaal, Ellen

    2017-04-01

    Permafrost stores twice as much carbon (C) as is currently present in the atmosphere. During recent years, warmer temperatures in the Arctic has caused rapid thawing of permafrost, which have dramatically altered permafrost C storage by increasing both microbial decomposition and plant productivity. Although current research focuses on the effects of climate change on these two processes, there are still no scientific consensus about the magnitude or even the direction of future C feedbacks from permafrost ecosystems. Field manipulation experiments have been widely used during the last decade to improve our knowledge about the net effects of permafrost thaw in the permafrost C storage. However, due to the slow response (decades) of permafrost ecosystems to environmental changes and the short-time nature of these experiments (usually shorter than 5-9 years), there are still concerns when attempting to extrapolate the results to predict long term effects. In addition, measurements are mostly taken exclusively during the summer season, without taking into account inter-annual variability in C fluxes and underestimating microbial activity throughout the cold season. The need to develop a comprehensive understanding of C fluxes over the entire year and at long temporal scales sets the basis of this study. This study aims to quantify the effects of permafrost thawing in permafrost C fluxes using a 12 years permafrost thaw experiment in northern Sweden. Our aims were to quantify the effect of permafrost thaw in both decomposition and primary production in active layer and newly thawed permafrost, and its implications for the C balance. Based on previous observations, we hypothesized that 1) soil decomposition rates were higher in manipulated thaw plots. However, 2) the observed increase in nutrients availability and the higher presence of vascular plants after thawing stimulate primary production, which compensates to some extent the increased C losses by respiration. To

  12. Automated freeze-thaw cycles for decellularization of tendon tissue - a pilot study.

    Science.gov (United States)

    Roth, Susanne Pauline; Glauche, Sina Marie; Plenge, Amelie; Erbe, Ina; Heller, Sandra; Burk, Janina

    2017-02-14

    Decellularization of tendon tissue plays a pivotal role in current tissue engineering approaches for in vitro research as well as for translation of graft-based tendon restoration into clinics. Automation of essential decellularization steps like freeze-thawing is crucial for the development of more standardized decellularization protocols and commercial graft production under good manufacturing practice (GMP) conditions in the future. In this study, a liquid nitrogen-based controlled rate freezer was utilized for automation of repeated freeze-thawing for decellularization of equine superficial digital flexor tendons. Additional tendon specimens underwent manually performed freeze-thaw cycles based on an established procedure. Tendon decellularization was completed by using non-ionic detergent treatment (Triton X-100). Effectiveness of decellularization was assessed by residual nuclei count and calculation of DNA content. Cytocompatibility was evaluated by culturing allogeneic adipose tissue-derived mesenchymal stromal cells on the tendon scaffolds. There were no significant differences in decellularization effectiveness between samples decellularized by the automated freeze-thaw procedure and samples that underwent manual freeze-thaw cycles. Further, we inferred no significant differences in the effectiveness of decellularization between two different cooling and heating rates applied in the automated freeze-thaw process. Both the automated protocols and the manually performed protocol resulted in roughly 2% residual nuclei and 13% residual DNA content. Successful cell culture was achieved with samples decellularized by automated freeze-thawing as well as with tendon samples decellularized by manually performed freeze-thaw cycles. Automated freeze-thaw cycles performed by using a liquid nitrogen-based controlled rate freezer were as effective as previously described manual freeze-thaw procedures for decellularization of equine superficial digital flexor tendons

  13. The cytoplasmic Cu,Zn superoxide dismutase of saccharomyces cerevisiae is required for resistance to freeze-thaw stress. Generation of free radicals during freezing and thawing

    DEFF Research Database (Denmark)

    Park, J I; Grant, C M; Davies, Michael Jonathan

    1998-01-01

    The involvement of oxidative stress in freeze-thaw injury to yeast cells was analyzed using mutants defective in a range of antioxidant functions, including Cu,Zn superoxide dismutase (encoded by SOD1), Mn superoxide dismutase (SOD2), catalase A, catalase T, glutathione reductase, gamma...

  14. Cryopreservation of collared peccary (Pecari tajacu) semen using different freezing curves, straw sizes, and thawing rates.

    Science.gov (United States)

    Silva, M A; Peixoto, G C X; Castelo, T S; Lima, G L; Silva, A M; Oliveira, M F; Silva, A R

    2013-08-01

    The objective of this study was to verify the effect of different freezing curves, straw sizes, and thawing rates on the cryopreservation of collared peccary semen. Twelve ejaculates were obtained from captive adult males by electroejaculation, and evaluated for sperm motility, kinetic rating, viability, morphology, and functional membrane integrity. The ejaculates were diluted in a coconut water extender (ACP-116c) with egg yolk and glycerol, packaged into 0.25 mL or 0.50 mL plastic straws and cryopreserved in liquid nitrogen following a slow (-10 °C/min) or a fast (-40 °C/min) freezing curve. After one week, samples were thawed at 37 °C/1 min or 70 °C/8s and evaluated as reported for fresh semen, and also for kinematic parameters (computerized analysis). A significant decrease in sperm motility and kinetic rating was observed after glycerol addition at 5 °C and also after thawing for all the treatments (Pstraw size and thawing rate were taken as reference (P>0.05). In general, values for sperm characteristics found after thawing at 37 °C were better preserved than at 70 °C (Pstraws, which were similar for semen packaging (P>0.05). The evaluation of the kinematic parameters of sperm motility confirmed these results at values varying from 20% to 30% motile sperm for the samples tha wed at 37 °C, and values fewer than 12% motile sperm for samples thawed at 70 °C (Pstraws, but the thawing should be conducted at 37 °C/1 min. Copyright © 2013 Elsevier Inc. All rights reserved.

  15. Effect of freeze-thawing on aggregate stability in a calcareous Mediterranean soil

    Science.gov (United States)

    Lozano, Elena; Temporal, Beatriz; Oltra, Ángel; Mataix-Solera, Jorge; Arcenegui, Victoria; García-Orenes, Fuensanta

    2013-04-01

    Soil freezing has been reported as both beneficial and detrimental for soil structure depending on various factors (Dagesse, 2011), but the subsequent thawing process has not been adequately investigated as a factor in determining the net effect of freezing and thawing. In this study changes in soil aggregate stability (AS) were studied under different moisture and speed of thawing conditions in a laboratory experiment. Conditions favoring sublimation and commonly experienced during the winter include bare soil surfaces and synoptic meteorological conditions of clear skies, low humidity, and moderate winds. Aggregate stability measured may therefore reflect the effects of drying of the soil aggregates via the freezing process and the resulting water content distribution following thawing. The soil used is from an agricultural area located in Sierra de Enguera (Valencia, E Spain). Soil samples were collected in February 2012 from the first 2.5 cm depth of A horizon. We also studied the effect of a mulch cover in buffering soil temperature during 2 months under field conditions using thermocouples and data-loggers. Soil samples at two initial water contents (10% and 40%) were subjected to different treatments, including not frozen (control), freeze-thaw (freezing at -4 °C for 3 h and thawing at room temperature for 24 h) and freeze-drying (freezing at -4 for 3h and thawing at 60 °C for 3 h in a forced air oven). We measured the possible soil disruption of soil aggregates quantifying the soil mass in the fractions 2-0.25 mm and

  16. Influence of vertical and lateral heat transfer on permafrost thaw, peatland landscape transition, and groundwater flow

    Science.gov (United States)

    Kurylyk, Barret; Masaki, Masaki; Quinton, William L.; McKenzie, Jeffrey M.; Voss, Clifford I.

    2016-01-01

    Recent climate change has reduced the spatial extent and thickness of permafrost in many discontinuous permafrost regions. Rapid permafrost thaw is producing distinct landscape changes in the Taiga Plains of the Northwest Territories, Canada. As permafrost bodies underlying forested peat plateaus shrink, the landscape slowly transitions into unforested wetlands. The expansion of wetlands has enhanced the hydrologic connectivity of many watersheds via new surface and near-surface flow paths, and increased streamflow has been observed. Furthermore, the decrease in forested peat plateaus results in a net loss of boreal forest and associated ecosystems. This study investigates fundamental processes that contribute to permafrost thaw by comparing observed and simulated thaw development and landscape transition of a peat plateau-wetland complex in the Northwest Territories, Canada from 1970 to 2012. Measured climate data are first used to drive surface energy balance simulations for the wetland and peat plateau. Near-surface soil temperatures simulated in the surface energy balance model are then applied as the upper boundary condition to a three-dimensional model of subsurface water flow and coupled energy transport with freeze-thaw. Simulation results demonstrate that lateral heat transfer, which is not considered in many permafrost models, can influence permafrost thaw rates. Furthermore, the simulations indicate that landscape evolution arising from permafrost thaw acts as a positive feedback mechanism that increases the energy absorbed at the land surface and produces additional permafrost thaw. The modeling results also demonstrate that flow rates in local groundwater flow systems may be enhanced by the degradation of isolated permafrost bodies.

  17. Bioavailability of soil organic matter and microbial community dynamics upon permafrost thaw.

    Science.gov (United States)

    Coolen, Marco J L; van de Giessen, Jeroen; Zhu, Elizabeth Y; Wuchter, Cornelia

    2011-08-01

    Amplified Arctic warming could thaw 25% of the permafrost area by 2100, exposing vast amounts of currently fixed organic carbon to microbially mediated decomposition and release of greenhouse gasses through soil organic matter (SOM) respiration. We performed time-series incubation experiments with Holocene permafrost soils at 4°C for up to 11 days to determine changes in exoenzyme activities (EEAs) (i.e. phosphatase, β-glucosidase, aminopeptidase) as a measure for the bioavailability of SOM in response to permafrost thaw. We also profiled SSU rRNA transcripts to follow the qualitative and quantitative changes in viable prokaryotes and eukaryotes during incubation. EEA, amount of rRNA transcripts and microbial community structures differed substantially between the various soil intervals in response to thaw: after 11 days of incubation, the active layer became slightly depleted in C and P and harboured bacterial phyla indicative of more oligotrophic conditions (Acidobacteria). A fast response in phosphatase and β-glucosidase upon thaw, and a predominance of active copiotrophic Bacteroidetes, showed that the upper permafrost plate serves as storage of easily degradable carbon derived from the overlying thawed active layer during summer. EEA profiles and microbial community dynamics furthermore suggest that the deeper and older permafrost intervals mainly contain recalcitrant SOM, and that extracellular soil-bound exoenzymes play a role in the initial cleavage of biopolymers, which could kick-start microbial growth upon thaw. Basidiomycetous fungi and Candidate Subdivision OP5 bacteria were the first to respond in freshly thawed deeper permafrost intervals, and might play an important role in the decomposition of recalcitrant SOM to release more labile substrates to support the major bacterial phyla (β-Proteobacteria, Actinobacteria, Firmicutes), which predominated thereafter. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

  18. Effect of freeze-thaw cycles on the nutritional quality of some selected Nigerian soups.

    Science.gov (United States)

    Raji, Akeem Olayemi; Akinoso, Rahman; Raji, Monsurat Oyewale

    2016-03-01

    Freezing and thawing are heat transfer processes, involving chemical changes which may greatly affect product quality. Due to sparse literature on freeze-thawed cycles and its effects on soups quality, the effect of freeze-thaw cycles on the nutritional quality of selected Nigerian soups has to be investigated. Soups (Ila, Ewedu, Ogbono, and Kuka) were prepared using standard recipes. The soups were packaged in plastic and aluminum containers, frozen at -20°C, and thawed with microwave oven, hot water (100°C), and at ambient condition for four cycles of 5-day interval. After each cycle, chemical compositions of the samples were determined using AOAC methods. Data were analyzed using ANOVA at P = 0.05. Moisture, protein, fat, crude fiber, ash, and carbohydrate contents of the freeze-thawed soups were 63.6-88.6%, 3.6-8.8%, 1.0-6.1%, 0.8-1.2%, 1.8-4.6%, and 0.9-15.6%, respectively. Mineral contents were iron (5.0-6.8 mg/100 g), calcium (68.1-190.8 mg/100 g), sodium (144.4-231.7 mg/100 g), potassium (200.4-302.1 mg/100 g), and phosphorus (228.0-337.2 mg/100 g). Vitamins were vitamin A (29.5-59.9 mg/100 g), vitamin B (10.1-36.4 mg/100 g), and vitamin E (28.4-90.2 mg/100 g). Microwave-thawed plastic soups had limited nutritional losses when compared with other thawing methods, and should not be extended beyond the third cycle because of increasing reduction in fat and protein, indicating deterioration.

  19. Microbial functional diversity covaries with permafrost thaw-induced environmental heterogeneity in tundra soil.

    Science.gov (United States)

    Yuan, Mengting M; Zhang, Jin; Xue, Kai; Wu, Liyou; Deng, Ye; Deng, Jie; Hale, Lauren; Zhou, Xishu; He, Zhili; Yang, Yunfeng; Van Nostrand, Joy D; Schuur, Edward A G; Konstantinidis, Konstantinos T; Penton, Christopher R; Cole, James R; Tiedje, James M; Luo, Yiqi; Zhou, Jizhong

    2018-01-01

    Permafrost soil in high latitude tundra is one of the largest terrestrial carbon (C) stocks and is highly sensitive to climate warming. Understanding microbial responses to warming-induced environmental changes is critical to evaluating their influences on soil biogeochemical cycles. In this study, a functional gene array (i.e., geochip 4.2) was used to analyze the functional capacities of soil microbial communities collected from a naturally degrading permafrost region in Central Alaska. Varied thaw history was reported to be the main driver of soil and plant differences across a gradient of minimally, moderately, and extensively thawed sites. Compared with the minimally thawed site, the number of detected functional gene probes across the 15-65 cm depth profile at the moderately and extensively thawed sites decreased by 25% and 5%, while the community functional gene β-diversity increased by 34% and 45%, respectively, revealing decreased functional gene richness but increased community heterogeneity along the thaw progression. Particularly, the moderately thawed site contained microbial communities with the highest abundances of many genes involved in prokaryotic C degradation, ammonification, and nitrification processes, but lower abundances of fungal C decomposition and anaerobic-related genes. Significant correlations were observed between functional gene abundance and vascular plant primary productivity, suggesting that plant growth and species composition could be co-evolving traits together with microbial community composition. Altogether, this study reveals the complex responses of microbial functional potentials to thaw-related soil and plant changes and provides information on potential microbially mediated biogeochemical cycles in tundra ecosystems. © 2017 John Wiley & Sons Ltd.

  20. Successful artificial insemination in the Asian elephant (Elephas maximus using chilled and frozen-thawed semen

    Directory of Open Access Journals (Sweden)

    Wongkalasin Warut

    2009-07-01

    Full Text Available Abstract Background Artificial insemination (AI using frozen-thawed semen is well established and routinely used for breeding in various mammalian species. However, there is no report of the birth of elephant calves following AI with frozen-thawed semen. The objective of the present study was to investigate the fertilizing ability of chilled and frozen-thawed semen in the Asian elephant following artificial insemination (AI. Methods Semen samples were collected by from 8 bulls (age range, 12-to 42-years by manual stimulation. Semen with high quality were either cooled to 4°C or frozen in liquid nitrogen (-196°C before being used for AI. Blood samples collected from ten elephant females (age range, 12-to 52-years were assessed for estrus cycle and elephants with normal cycling were used for AI. Artificial insemination series were conducted during 2003 to 2008; 55 and 2 AI trials were conducted using frozen-thawed and chilled semen, respectively. Pregnancy was detected using transrectal ultrasonography and serum progestagen measurement. Results One female (Khod inseminated with chilled semen became pregnant and gave birth in 2007. The gestation length was 663 days and the sex of the elephant calf was male. One female (Sao inseminated with frozen-thawed semen showed signs of pregnancy by increasing progestagen levels and a fetus was observed for 5 months by transrectal ultrasonography. Conclusion This is the first report showing pregnancy following AI with frozen-thawed semen in the Asian elephant. Successful AI in the Asian elephant using either chilled or frozen-thawed semen is a stepping stone towards applying this technology for genetic improvement of the elephant population.

  1. Shifts of tundra bacterial and archaeal communities along a permafrost thaw gradient in Alaska.

    Science.gov (United States)

    Deng, Jie; Gu, Yunfu; Zhang, Jin; Xue, Kai; Qin, Yujia; Yuan, Mengting; Yin, Huaqun; He, Zhili; Wu, Liyou; Schuur, Edward A G; Tiedje, James M; Zhou, Jizhong

    2015-01-01

    Understanding the response of permafrost microbial communities to climate warming is crucial for evaluating ecosystem feedbacks to global change. This study investigated soil bacterial and archaeal communities by Illumina MiSeq sequencing of 16S rRNA gene amplicons across a permafrost thaw gradient at different depths in Alaska with thaw progression for over three decades. Over 4.6 million passing 16S rRNA gene sequences were obtained from a total of 97 samples, corresponding to 61 known classes and 470 genera. Soil depth and the associated soil physical-chemical properties had predominant impacts on the diversity and composition of the microbial communities. Both richness and evenness of the microbial communities decreased with soil depth. Acidobacteria, Verrucomicrobia, Alpha- and Gamma-Proteobacteria dominated the microbial communities in the upper horizon, whereas abundances of Bacteroidetes, Delta-Proteobacteria and Firmicutes increased towards deeper soils. Effects of thaw progression were absent in microbial communities in the near-surface organic soil, probably due to greater temperature variation. Thaw progression decreased the abundances of the majority of the associated taxa in the lower organic soil, but increased the abundances of those in the mineral soil, including groups potentially involved in recalcitrant C degradation (Actinomycetales, Chitinophaga, etc.). The changes in microbial communities may be related to altered soil C sources by thaw progression. Collectively, this study revealed different impacts of thaw in the organic and mineral horizons and suggests the importance of studying both the upper and deeper soils while evaluating microbial responses to permafrost thaw. © 2014 John Wiley & Sons Ltd.

  2. Carbon Dioxide and Methane Fluxes along the Thaw Lake Cycle Chronosequence, Arctic Coastal Plain of Alaska

    Science.gov (United States)

    Sturtevant, C. S.; Oechel, W. C.

    2011-12-01

    Thaw lakes and drained thaw lake basins comprise the majority of the land surface on the Arctic Coastal Plain of Alaska near Barrow. These landscape features are thought to be part of a several thousand year cycle in which lakes form and drain. Upon drainage, the lake basins appear to undergo a succession of vegetation and soil conditions accompanying ice wedge growth and microtopographic development. These ecosystem changes represent potentially significant variation in land-atmosphere carbon fluxes, yet remain understudied in this respect, especially given the large proportion of the landscape they occupy. The chronosequence from active thaw lakes to ancient thaw lake basins (up to 5500 years old) on the Arctic Coastal Plain near Barrow provides an excellent opportunity to study how and why certain ecosystem changes affect carbon storage and release for this region. It also provides the ability to evaluate spatial variation in carbon fluxes, which will help to constrain uncertainty in and the representativeness of regional estimates using long term flux towers. In this study we used portable meteorological towers to measure the land-atmosphere fluxes of CO2 and CH4 along four replicate sets of the thaw lake basin chronosequence (five age classes each) near Barrow, Alaska during the growing season of 2011. The flux towers were equipped with eddy covariance and environmental instrumentation and were augmented with transect measurements of thaw depth and soil moisture. Here we present our preliminary findings on the differences in and controls of CO2 and CH4 flux along the thaw lake cycle chronosequence. We also discuss regional estimates in the context of observed spatial variability.

  3. Characteristics of ultrasonic acoustic emissions from walnut branches during freeze-thaw-induced embolism formation.

    Science.gov (United States)

    Kasuga, Jun; Charrier, Guillaume; Uemura, Matsuo; Améglio, Thierry

    2015-04-01

    Ultrasonic acoustic emission (UAE) methods have been applied for the detection of freeze-thaw-induced embolism formation in water conduits of tree species. Until now, however, the exact source(s) of UAE has not been identified especially in angiosperm species, in which xylem tissues are composed of diverse types of cells. In this study, UAE was recorded from excised branches of walnut (Juglans regia cv. Franquette) during freeze-thaw cycles, and attempts were made to characterize UAEs generated by cavitation events leading to embolism formation according to their properties. During freeze-thaw cycles, a large number of UAEs were generated from the sample segments. However, the cumulative numbers of total UAE during freeze-thawing were not correlated with the percentage loss of hydraulic conductivity after thawing, suggesting that the sources of UAE were not only cavitation leading to embolism formation in vessels. Among the UAEs, cumulative numbers of UAEs with absolute energy >10.0 fJ strongly correlated with the increase in percentage loss of hydraulic conductivity. The high absolute energy of the UAEs might reflect the formation of large bubbles in the large lumen of vessels. Therefore, UAEs generated by cavitation events in vessels during freeze-thawing might be distinguished from other signals according to their magnitudes of absolute energy. On the other hand, the freezing of xylem parenchyma cells was followed by a certain number of UAEs. These results indicate the possibility that UAE methods can be applied to the detection of both freeze-thaw-induced embolism and supercooling breakdown in parenchyma cells in xylem. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  4. Characteristics of ultrasonic acoustic emissions from walnut branches during freeze–thaw-induced embolism formation

    Science.gov (United States)

    Kasuga, Jun; Charrier, Guillaume; Uemura, Matsuo; Améglio, Thierry

    2015-01-01

    Ultrasonic acoustic emission (UAE) methods have been applied for the detection of freeze–thaw-induced embolism formation in water conduits of tree species. Until now, however, the exact source(s) of UAE has not been identified especially in angiosperm species, in which xylem tissues are composed of diverse types of cells. In this study, UAE was recorded from excised branches of walnut (Juglans regia cv. Franquette) during freeze–thaw cycles, and attempts were made to characterize UAEs generated by cavitation events leading to embolism formation according to their properties. During freeze–thaw cycles, a large number of UAEs were generated from the sample segments. However, the cumulative numbers of total UAE during freeze–thawing were not correlated with the percentage loss of hydraulic conductivity after thawing, suggesting that the sources of UAE were not only cavitation leading to embolism formation in vessels. Among the UAEs, cumulative numbers of UAEs with absolute energy >10.0 fJ strongly correlated with the increase in percentage loss of hydraulic conductivity. The high absolute energy of the UAEs might reflect the formation of large bubbles in the large lumen of vessels. Therefore, UAEs generated by cavitation events in vessels during freeze–thawing might be distinguished from other signals according to their magnitudes of absolute energy. On the other hand, the freezing of xylem parenchyma cells was followed by a certain number of UAEs. These results indicate the possibility that UAE methods can be applied to the detection of both freeze–thaw-induced embolism and supercooling breakdown in parenchyma cells in xylem. PMID:25662846

  5. Snowcover Influences Upon Episodic Release of Nitrous Oxide from Agricultural Soils During Spring Thaw

    Science.gov (United States)

    Helgason, W.; Farrell, R.; Ens, J.; Lemke, R.; David, C.

    2015-12-01

    In regions where agricultural soils seasonally freeze, such as the Canadian prairies, up to 60-70% of the annual nitrous oxide (N2O) emission can occur during the soil thaw period. The conditions responsible for this episodic release of N2O are poorly understood. In order to elucidate the influencing factors a replicated plot study was conducted in Outlook, Saskatchewan, Canada (51.5°N) during the 2014-2015 winter period. The study compared soil thermal conditions and soil gas fluxes (nitrous oxide and carbon dioxide) from plots that had the snow periodically removed and those on which snow was allowed to accumulate. Soil gas fluxes were measured using an automated chamber system (Gasmet DX4030 FTIR analyzer and Licor Li-8100 chamber system) and analyzer. Soil conditions were continuously monitored throughout the winter and thaw periods. Owing to the insulating effect of snow, the snow free plots were colder during the mid-winter period, but thawed 3-4 days earlier than the snow covered treatment. Following thaw, the snow-free plots were 2-3 degrees warmer than the snow-covered plots for 5-7 days before reaching a similar thermal regime. Due to the differences in the timing of soil thaw and the pre- and post-thaw thermal conditions, cumulative and peak N2O emissions were much higher from the plots that had been kept snow-free. These results suggest that agricultural practices which influence snow redistribution may have an effect upon spring soil gas fluxes. This study also highlights the importance of incorporating snowmelt and soil thaw physics into process-based greenhouse gas models.

  6. The Canadian Experiment for Freeze/Thaw in 2012 or 2013 CanEx-FT12 or FT13

    Science.gov (United States)

    Belair, Stephane; Bernier, Monique; Colliander, Andreas; Jackson, Thomas; McDonald, Kyle; Walker, Anne

    2011-01-01

    General objectives of the experiment are: Pre-launch Calibration/Validation of SMAP Freeze/Thaw products and retrieval algorithms and rehearsal for Soil Moisture Active-Passive (SMAP) post launch validation. The basis of the radar freeze-thaw measurement is the large shift in dielectric constant and backscatter (dB) between predominantly frozen & thawed conditions. The Dielectric constant of liquid water varies with frequency, whereas that of pure ice is constant

  7. Influence of Freeze-Thaw Damage on the Steel Corrosion and Bond-Slip Behavior in the Reinforced Concrete

    Directory of Open Access Journals (Sweden)

    Fangzhi Zhu

    2016-01-01

    Full Text Available This paper mainly studies the behavior of steel corrosion in various reinforced concrete under freeze-thaw environment. The influence of thickness of concrete cover is also discussed. Additionally, the bond-slip behavior of the reinforced concrete after suffering the freeze-thaw damage and steel corrosion has also be presented. The results show that the freeze-thaw damage aggravates the steel corrosion in concrete, and the results become more obvious in the concrete after suffering serious freeze-thaw damage. Compared with the ordinary concrete, both air entrained concrete and waterproofing concrete possess better resistance to steel corrosion under the same freeze-thaw environment. Moreover, increasing the thicknesses of concrete cover is also an effective method of improving the resistance to steel corrosion. The bond-slip behavior of reinforced concrete with corroded steel decreases with the increase of freeze-thaw damage, especially for the concrete that suffered high freeze-thaw cycles. Moreover, there exists a good correlation between the parameters of bond-slip and freeze-thaw cycles. The steel corrosion and bond-slip behavior of reinforced concrete should be considered serious under freeze-thaw cycles environment, which significantly impact the durability and safety of concrete structure.

  8. Development of the Soil Moisture Active Passive (SMAP) radiometer derived landscape freeze/thaw product

    Science.gov (United States)

    Colliander, A.; Xu, X.; Dunbar, R. S.; Derksen, C.; Kim, Y.; Kimball, J. S.

    2016-12-01

    A baseline SMAP mission objective was to determine the land surface binary freeze/thaw (FT) state for northern (>45°N) regions with 80% spatial classification accuracy at 3 km resolution and 2-day average intervals. These requirements were initially achieved from the SMAP radar until the sensor failed in July 2015. The FT algorithm is now transitioning to using SMAP radiometer inputs. The main compromises of this change are a coarse (36 km) radiometer footprint, enhanced noise and potential FT signal degradation from seasonal vegetation biomass, soil moisture and surface inundation changes. The new daily passive FT product (L3_FT_P) is based on the same seasonal threshold algorithm as the radar derived product (L3_FT_A): instantaneous SMAP measurements are compared to reference signatures acquired during seasonal frozen and thawed states. Instead of radar inputs, the normalized polarization ratio (NPR) is calculated from SMAP radiometer measurements. The L3_FT_P algorithm is applied using NPR inputs, whereby NPR decreases and increases are associated with respective landscape freezing and thawing. A lower NPR under frozen conditions is due to smaller V-pol brightness temperature increases and larger H-pol increases. Using in situ measurements from core validation sites, the temporal behavior of backscatter and NPR measurements were evaluated during the spring 2015 radar and radiometer overlap period. The transition from frozen to thawed states produced a NPR response similar in timing and magnitude to the radar response, resulting in similar freeze to thaw seasonal transition dates. While the post-thaw radar backscatter consistently remained at elevated values relative to the frozen state, the NPR drifted downwards following the main thaw transition (due to de-polarization of the scene), which may introduce false freeze classification errors. Both radar and radiometer results tended to lead observed soil thawing due to strong sensitivity of the microwave

  9. Freezing-thawing action in the deterioration of the stones of Chambord Castle

    Science.gov (United States)

    Alomari, Asaad; Brunetaud, Xavier; Beck, Kevin; Al-Mukhtar, Muzahim

    2013-04-01

    Limestone is very common in architecture (monuments and cultural heritage buildings) and used in the sculptures. The soft and porous limestone soaks up water and show weathering patterns and forms: alveolar weathering, granular disintegration, efflorescences. Freezing-thawing actions can be considered as one of the processes that contribute in the deterioration of stones located in the "cold regions" characterized with air temperatures below freezing point temperature. The amount of water within the pore space of the stones is a crucial factor of the decay. The experimental work presented in this paper is a part of a research program that aims to study the mechanisms that lead to the degradation of stone building materials due to the variation of climatic conditions. The analysis of the meteorological data of the field around the castle of Chambord shows the magnitude of temperature variations and the frequency of freezing-thawing cycles. The critical degrees of saturation at which the stone start to deteriorate after treatment with freezing-thawing cycles were examined in the tests conducted. The study concerns two porous limestone used in the construction and conservation of Chambord castle; highly porous Tuffeau stone having a total porosity of about 48 %, and medium porous Richemont stone with a total porosity of 27 %. Richemont stone has been used as a substitute stone of the degraded Tuffeau stone on the castle. The main physical properties, total porosity, apparent dry density and skeleton density and sound velocity for mechanical properties were measured for the stone samples before and during freezing-thawing cycles. ASTM (D5312-04) procedure was applied in the freezing-thawing tests. Tuffeau and Richmond samples were prepared at nine different degrees of saturations; 0, 20, 40, 70, 80, 85, 90, 95 and 100%, and properties were measured after different freezing-thawing cycles conditions; 2, 4, 8, 12, 16, 20, 30 and 50 cycles. The results of these tests show

  10. Enhanced Transport of Colloid And Metal Cations by Freeze-thaw Cycles

    Science.gov (United States)

    Mohanty, S. K.; Ryan, J. N.; Saiers, J. E.; Laboratory experiment

    2011-12-01

    Understanding the mechanisms of colloid mobilization is essential to predicting the importance of colloid-facilitated transport of contaminants in subsurface environments. This study was conducted to evaluate the effect of freeze-thaw cycles on the mobilization of colloids and colloid-facilitated transport of cesium and strontium in intact soil cores. The soil cores were collected from a watershed in Tennessee, USA, where the soils are weathered from limey shale with fractured saprolite subsoils that have illite as the primary clay mineral. Each freeze-thaw cycle involved freezing the contaminated soil at -15 °C for 36 h followed by thawing at 25 °C for 24 h and infiltration of rainwater for 6 h. An 18-port grid was used to collect water sample from preferential flow paths. The amount of colloids mobilized by the freeze-thaw process was compared with the amount of colloids mobilized from a control soil-core at room temperature. The colloids mobilized during freeze-thaw were characterized using x-ray diffraction analysis. Results of current study indicated an enhanced mobilization of colloids from frozen soil compared to unfrozen soil. Colloids mobilized after five freeze-thaw cycles were two times higher than the amount of colloids mobilized from unfrozen soil. The duration of freezing had no significant impact on the amount of colloids mobilized. Results of XRD analysis indicated an increase in clay mineral and iron-containing minerals and a decrease in quartz fractions in the mobilized colloids compared to the soil from which colloids were mobilized. The soil consisted of 35.7% clay minerals, 43.3% quartz, and 1.5% iron-containing minerals including ferruginous smectite, goethite, and amphibole. In contrast, colloids mobilized from the soil by freeze-thaw cycles had 64.3% clay minerals, 21.7% quartz, and 5.5% of iron-containing minerals. The colloids mobilized in control soil had 73.7% clay minerals, 3.5% quartz, and 4.6% iron-containing minerals. The colloidal

  11. Effects of permafrost thaw on nitrogen availability and plant nitrogen acquisition in Interior Alaska

    Science.gov (United States)

    Finger, R.; Euskirchen, E. S.; Turetsky, M.

    2013-12-01

    The degradation of ice-rich permafrost, which covers a large portion of Interior Alaska, typically leads to thermokarst and increases in soil saturation. As a result, conifer peat plateaus degrade and are often replaced by wet collapse scar bogs. This state change results in profound changes in regional hydrology, biogeochemical cycling, and plant community composition. Preliminary data suggest that permafrost thaw can increase surface soil inorganic nitrogen (IN) concentrations but it is still unknown whether these changes in nutrient availability are short-lived (pulse releases) and whether or not they impact collapse scar vegetation composition or productivity, particularly as collapse scars undergo succession with time-after-thaw. Therefore we are currently examining changes in plant community composition, N availability and plant N acquisition along three thermokarst gradients in Interior Alaska. Each gradient is comprised of a forested permafrost peat plateau, adjacent ecotones experiencing active permafrost degradation (including a collapsing forest canopy and a saturated moat), and a collapse scar bog where permafrost has completely degraded. We predicted that IN concentrations would be highest along the active thaw margin, and lowest in the peat plateau. We also predicted that IN concentrations would be positively related to shifts in vegetation community composition, nutrient use efficiency (NUE) and tissue 15N concentrations. Preliminary results have shown that IN concentrations increase in newer collapse scar features as well as with thaw depth. Our data also show a shift from feather moss and ericaceous shrub-dominate understories in the permafrost plateau to Sphagnum and sedge dominated thaw ecotone and bog communities. Further successional development of the collapse scar bog results in the reintroduction of small evergreen and deciduous shrubs as the peat mat develops. Over time, collapse scar succession and peat accumulation appears to lead to

  12. Characteristics of sugar surfactants in stabilizing proteins during freeze-thawing and freeze-drying.

    Science.gov (United States)

    Imamura, Koreyoshi; Murai, Katsuyuki; Korehisa, Tamayo; Shimizu, Noriyuki; Yamahira, Ryo; Matsuura, Tsutashi; Tada, Hiroko; Imanaka, Hiroyuki; Ishida, Naoyuki; Nakanishi, Kazuhiro

    2014-06-01

    Sugar surfactants with different alkyl chain lengths and sugar head groups were compared for their protein-stabilizing effect during freeze-thawing and freeze-drying. Six enzymes, different in terms of tolerance against inactivation because of freeze-thawing and freeze-drying, were used as model proteins. The enzyme activities that remained after freeze-thawing and freeze-drying in the presence of a sugar surfactant were measured for different types and concentrations of sugar surfactants. Sugar surfactants stabilized all of the tested enzymes both during freeze-thawing and freeze-drying, and a one or two order higher amount of added sugar surfactant was required for achieving protein stabilization during freeze-drying than for the cryoprotection. The comprehensive comparison showed that the C10-C12 esters of sucrose or trehalose were the most effective through the freeze-drying process: the remaining enzyme activities after freeze-thawing and freeze-drying increased at the sugar ester concentrations of 1-10 and 10-100 μM, respectively, and increased to a greater extent than for the other surfactants at higher concentrations. Results also indicate that, when a decent amount of sugar was also added, the protein-stabilizing effect of a small amount of sugar ester through the freeze-drying process could be enhanced. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

  13. Identification of Soil Freezing and Thawing States Using SAR Polarimetry at C-Band

    Directory of Open Access Journals (Sweden)

    Thomas Jagdhuber

    2014-03-01

    Full Text Available The monitoring of soil freezing and thawing states over large areas is very challenging on ground. In order to investigate the potential and the limitations of space-borne SAR polarimetry at C-band for soil state survey, analyses were conducted on an entire winter time series of fully polarimetric RADARSAT-2 data from 2011/2012 to identify freezing as well as thawing states within the soil. The polarimetric data were acquired over the Sodankylä test site in Finland together with in situ measurements of the soil and the snow cover. The analyses indicate clearly that the dynamics of the polarimetric entropy and mean scattering alpha angle are directly correlated to soil freezing and thawing states, even under distinct dry snow cover. First modeling attempts using the Extended Bragg soil scattering model justify the observed trends, which indicate surface-like scattering during frozen soil conditions and multiple/volume scattering for thawed soils. Hence, these first investigations at C-band foster motivation to work towards a robust polarimetric detection of soil freezing and thawing states as well as their transition phase.

  14. Effects of Freezing and Thawing Cycle on Mechanical Properties and Stability of Soft Rock Slope

    Directory of Open Access Journals (Sweden)

    Yanlong Chen

    2017-01-01

    Full Text Available To explore the variation laws of mechanical parameters of soft rock and the formed slope stability, an experiment was carried out with collected soft rock material specimens and freezing and thawing cycle was designed. Meanwhile, a computational simulation analysis of the freezing-thawing slope stability was implemented. Key factors that influence the strength of frozen rock specimens were analyzed. Results showed that moisture content and the number of freezing-thawing cycles influenced mechanical parameters of soft rock significantly. With the increase of moisture content, cohesion of frozen soft rock specimens presents a quadratic function decrease and the internal friction angle shows a negative exponential decrease. The stability coefficient of soft rock material slope in seasonal freeze soil area declines continuously. With the increase of freezing and thawing cycle, both cohesion and internal friction angle of soft rock decrease exponentially. The higher the moisture content, the quicker the reduction. Such stability coefficient presents a negative exponential reduction. After three freezing and thawing cycles, the slope stability coefficient only changes slightly. Findings were finally verified by the filed database.

  15. Structural properties of monoclonal antibody aggregates induced by freeze-thawing and thermal stress.

    Science.gov (United States)

    Hawe, Andrea; Kasper, Julia Christina; Friess, Wolfgang; Jiskoot, Wim

    2009-09-10

    Aggregation of monoclonal antibodies can be induced by freeze-thawing and elevated temperature, typical stress factors during development, production and storage. Our aim was to characterize structural properties of aggregates formed after freeze-thawing and thermal stressing of humanized monoclonal IgG(1) antibody (IgG). Formulations with 1.0mg/ml IgG in 100mM phosphate pH 7.2 were subjected to freeze-thawing and heating and characterized by spectroscopic techniques (UV-absorption, CD, ATR-FTIR and fluorescence), light obscuration, dynamic light scattering, SDS-PAGE, AF4 with UV and MALLS detection, and HP-SEC with UV and online fluorescent dye detection. Thermal stress led to an increased formation of dimers and soluble oligomers (HP-SEC, AF4). Aggregates smaller than 30nm were measured (DLS), next to slightly elevated particle levels in the mum range (light obscuration). Aggregates created by heating were in part covalently linked (SDS-PAGE) and made up of conformationally perturbed monomers (CD, ATR-FTIR, extrinsic dye fluorescence). Aggregation after freeze-thawing was manifested primarily in particle formation in the mum range. These aggregates were noncovalently linked (SDS-PAGE) and composed of native-like monomers, as obvious from CD, ATR-FTIR and extrinsic dye fluorescence spectroscopy. In conclusion, the complementary methods used in this study revealed that heating and freeze-thawing induced aggregates differ significantly in their physico-chemical characteristics.

  16. Leachate Properties and Cadmium Migration Through Freeze-thaw Treated Soil Columns.

    Science.gov (United States)

    Xu, Meng; Zheng, Yue; Chen, Weiwei; Mao, Na; Guo, Ping

    2017-01-01

    Soil column leaching experiments were conducted to study the effects of multiple freeze-thaw cycles on the vertical migration of cadmium (Cd). Three Cd-spiked leaching solutions of different properties were derived from snowmelt, sludge, and straw, designated as B, W and J, respectively. The leaching solutions varied in dissolved organic matter (DOM) concentrations in the order of J > W > B. Changes in leachate properties and Cd concentration were observed. The results showed that pH values of all the leachate solutions through freeze-thaw treated soil columns were higher than those of leachates through unfrozen soils. However, electrical conductivity (EC) values decreased compared with leachates in unfrozen treated soil columns. Although the concentrations of DOM in leachate solutions had no evident differences between the freeze-thaw and unfrozen treated soil columns, the concentrations of DOM in the leachate solutions B, W and J were different. Freeze-thaw cycles resulted in increased concentrations of Cd in the leachate solutions in the order J > W > B, and promoted a deeper migration of Cd in the soil columns. Thus, it was shown that freeze-thaw cycles may increase the risk of groundwater pollution by Cd.

  17. Increasing vaginal progesterone gel supplementation after frozen-thawed embryo transfer significantly increases the delivery rate

    DEFF Research Database (Denmark)

    Alsbjerg, Birgit; Polyzos, Nikolaos P; Elbaek, Helle Olesen

    2013-01-01

    The aim of this study was to evaluate the reproductive outcome in patients receiving frozen-thawed embryo transfer before and after doubling of the vaginal progesterone gel supplementation. The study was a retrospective study performed in The Fertility Clinic, Skive Regional Hospital, Denmark....... A total of 346 infertility patients with oligoamenorrhoea undergoing frozen-thawed embryo transfer after priming with oestradiol and vaginal progesterone gel were included. The vaginal progesterone dose was changed from 90mg (Crinone) once a day to twice a day and the reproductive outcome during the two...... rate (8.7% versus 20.5%, respectively; P=0.002). Doubling of the vaginal progesterone gel supplementation during frozen-thawed embryo transfer cycles decreased the early pregnancy loss rate, resulting in a significantly higher delivery rate. This study evaluated the reproductive outcome of 346 women...

  18. Antioxidant Effect of Xanthan Gum on Ram Sperm after Freezing and Thawing.

    Science.gov (United States)

    Gastal, G DA; Silva, E F; Mion, B; Varela Junior, A S; Rosa, C E; Corcini, C D; Mondadori, R G; Vieira, A D; Bianchi, I; Lucia, T

    Xanthan gum is used as thickener in media to preserve food products, having cryoprotectant and antioxidant properties that may be relevant for sperm cryopreservation. To evaluate the effects of adding xanthan gum to freezing extenders on post-thawing quality and oxidant activity of ram sperm. Ejaculates from seven rams extended TRIS-egg yolk-glycerol were split in three treatments including xanthan gum (0.15%; 0.20%; and 0.25%) and a control with no xanthan gum. After thawing, motility and production of reactive oxygen species (ROS) with 0.20% and 0.25% xanthan gum were lower than for the control (P membrane, acrosome and DNA did not differ (P > 0.05). Xanthan gum at 0.20% and 0.25% may be an efficient antioxidant for frozen-thawed ram sperm, due to the reduction in ROS production.

  19. FREEZING AND THAWING TIME PREDICTION METHODS OF FOODS II: NUMARICAL METHODS

    Directory of Open Access Journals (Sweden)

    Yahya TÜLEK

    1999-03-01

    Full Text Available Freezing is one of the excellent methods for the preservation of foods. If freezing and thawing processes and frozen storage method are carried out correctly, the original characteristics of the foods can remain almost unchanged over an extended periods of time. It is very important to determine the freezing and thawing time period of the foods, as they strongly influence the both quality of food material and process productivity and the economy. For developing a simple and effectively usable mathematical model, less amount of process parameters and physical properties should be enrolled in calculations. But it is a difficult to have all of these in one prediction method. For this reason, various freezing and thawing time prediction methods were proposed in literature and research studies have been going on.

  20. Compressive Strength, Chloride Permeability, and Freeze-Thaw Resistance of MWNT Concretes under Different Chemical Treatments

    Directory of Open Access Journals (Sweden)

    Xingang Wang

    2014-01-01

    Full Text Available This study investigated compressive strength, chloride penetration, and freeze-thaw resistance of multiwalled carbon nanotube (MWNT concrete. More than 100 cylindrical specimens were used to assess test variables during sensitivity observations, including water-cement ratios (0.75, 0.5, and 0.4 and exposure to chemical agents (including gum arabic, propanol, ethanol, sodium polyacrylate, methylcellulose, sodium dodecyl sulfate, and silane. To determine the adequate sonication time for MWNT dispersal in water, the compressive strengths of MWNT concrete cylinders were measured after sonication times ranging from 2 to 24 minutes. The results demonstrated that the addition of MWNT can increase the compressive strength of concrete by up to 108%. However, without chemical treatment, MWNT concretes tend to have poor freeze-thaw resistance. Among the different chemical treatments, MWNT concrete treated with sodium polyacrylate has the best compressive strength, chloride resistance, and freeze-thaw durability.

  1. Compressive strength, chloride permeability, and freeze-thaw resistance of MWNT concretes under different chemical treatments.

    Science.gov (United States)

    Wang, Xingang; Rhee, Inkyu; Wang, Yao; Xi, Yunping

    2014-01-01

    This study investigated compressive strength, chloride penetration, and freeze-thaw resistance of multiwalled carbon nanotube (MWNT) concrete. More than 100 cylindrical specimens were used to assess test variables during sensitivity observations, including water-cement ratios (0.75, 0.5, and 0.4) and exposure to chemical agents (including gum arabic, propanol, ethanol, sodium polyacrylate, methylcellulose, sodium dodecyl sulfate, and silane). To determine the adequate sonication time for MWNT dispersal in water, the compressive strengths of MWNT concrete cylinders were measured after sonication times ranging from 2 to 24 minutes. The results demonstrated that the addition of MWNT can increase the compressive strength of concrete by up to 108%. However, without chemical treatment, MWNT concretes tend to have poor freeze-thaw resistance. Among the different chemical treatments, MWNT concrete treated with sodium polyacrylate has the best compressive strength, chloride resistance, and freeze-thaw durability.

  2. Effect of freezing on electrical properties and quality of thawed chicken breast meat.

    Science.gov (United States)

    Wei, Ran; Wang, Peng; Han, Minyi; Chen, Tianhao; Xu, Xinglian; Zhou, Guanghong

    2017-04-01

    The objective of this research was to study the electrical properties and quality of frozen-thawed chicken breast meat and to investigate the relationship between these parameters at different times of frozen storage. Thawed samples of chicken breast muscles were evaluated after being kept in frozen storage at -18°C for different periods of time (1, 2, 3, 4, 5, 6, 7, and 8 months). The results showed that water-holding capacity (WHC) and protein solubility decreased while thiobarbituric acid-reactive substances content increased with increasing storage time. The impedance module of samples decreased during 8-month frozen storage. Pearson correlation coefficients showed that the impedance change ratio (Q value) was significantly (pprotein solubility, indicating a good relationship between the electrical properties and qualities of frozen-thawed chicken breast meat. Impedance measurement has a potential to assess the quality of frozen chicken meat combining with quality indices.

  3. Capabilities of scatterometer for detection of diurnal thaw and refreeze of snow cover

    Science.gov (United States)

    Bartsch, A.; Naeimi, V.; Wagner, W.

    2009-04-01

    Microwave sensors with short wavelengths such as SeaWinds Quikscat (Ku-band) are sensitive to changes at snow surfaces due to thaw. Especially scatterometer can provide several measurements per day at high latitudes. Diurnal differences are investigated in a range of studies since they indicate exactly when snowmelt is taking place. Large changes in backscatter between morning and evening acquisitions are characteristic for the snowmelt period, when freezing takes place over night and thawing of the surface during the day. A change from volume to surface scattering occurs in case of melting. The actual number of dates of snow thaw is of most interest for glacier mass balance studies but the final disappearance of snow together with the length of spring thaw is required in regions with seasonal snow cover. When significant changes due to freeze/thaw cycling cease, closed snow cover also disappears. The exact day of year of beginning and end of freeze/thaw cycling can be clearly determined using QuikScat with consideration of long-term noise in order to exclude unnatural effects and changes in soil moisture and snow pack characteristics. SeaWinds Quikscat measurements are available since 1999. The first entire snowmelt period on the northern hemisphere is covered in 2000. A further scatteromter which provides the necessary observation intervals at high latitudes is the Metop ASCAT. It acquires data with %80 daily global coverage but at a longer wavelength (C-band) and different incidence angles since 2007. Comparison examples showing the capabilities of the two different sensors for the purpose of snowmelt detection are presented for high latitude regions and mountainous terrain at mid latitudes (Alps).

  4. Electrical and seismic response of saline permafrost soil during freeze - Thaw transition

    Science.gov (United States)

    Wu, Yuxin; Nakagawa, Seiji; Kneafsey, Timothy J.; Dafflon, Baptiste; Hubbard, Susan

    2017-11-01

    We conducted laboratory studies on the geophysical signals from Arctic saline permafrost soils to help understand the physical and mechanical processes during freeze-thaw cycles. Our results revealed low electrical resistivity (freezing process, affected by concurrent changes of temperature, salinity, and ice formation. An anomalous induced polarization response was first observed during the transient period of supercooling and the onset of ice nucleation. Seismic measurements showed a characteristic maximal attenuation at the temperatures immediately below the freezing point, followed by a decrease with decreasing temperature. The calculated elastic moduli showed a non-hysteric response during the freeze - thaw cycle, which was different from the concurrently measured electrical resistivity response where a differential resistivity signal is observed depending on whether the soil is experiencing freezing or thawing. The differential electrical resistivity signal presents challenges for unfrozen water content estimation based on Archie's law. Using an improved formulation of Archie's law with a variable cementation exponent, the unfrozen water content estimation showed a large variation depending on the choice of the resistivity data during either a freezing or thawing cycle. Combining the electrical and seismic results, we suggest that, rather than a large hysteresis in the actual unfrozen water content, the shift of the resistivity response may reflect the changes of the distribution pattern of the unfrozen water (or ice) in the soil matrix during repeated freeze and thaw processes. Collectively, our results provide an improved petrophysical understanding of the physical and mechanical properties of saline permafrost during freeze - thaw transitions, and suggest that large uncertainty may exist when estimating the unfrozen water content using electrical resistivity data.

  5. Potential Arctic tundra vegetation shifts in response to changing temperature, precipitation and permafrost thaw

    Directory of Open Access Journals (Sweden)

    H.-J. van der Kolk

    2016-11-01

    Full Text Available Over the past decades, vegetation and climate have changed significantly in the Arctic. Deciduous shrub cover is often assumed to expand in tundra landscapes, but more frequent abrupt permafrost thaw resulting in formation of thaw ponds could lead to vegetation shifts towards graminoid-dominated wetland. Which factors drive vegetation changes in the tundra ecosystem are still not sufficiently clear. In this study, the dynamic tundra vegetation model, NUCOM-tundra (NUtrient and COMpetition, was used to evaluate the consequences of climate change scenarios of warming and increasing precipitation for future tundra vegetation change. The model includes three plant functional types (moss, graminoids and shrubs, carbon and nitrogen cycling, water and permafrost dynamics and a simple thaw pond module. Climate scenario simulations were performed for 16 combinations of temperature and precipitation increases in five vegetation types representing a gradient from dry shrub-dominated to moist mixed and wet graminoid-dominated sites. Vegetation composition dynamics in currently mixed vegetation sites were dependent on both temperature and precipitation changes, with warming favouring shrub dominance and increased precipitation favouring graminoid abundance. Climate change simulations based on greenhouse gas emission scenarios in which temperature and precipitation increases were combined showed increases in biomass of both graminoids and shrubs, with graminoids increasing in abundance. The simulations suggest that shrub growth can be limited by very wet soil conditions and low nutrient supply, whereas graminoids have the advantage of being able to grow in a wide range of soil moisture conditions and have access to nutrients in deeper soil layers. Abrupt permafrost thaw initiating thaw pond formation led to complete domination of graminoids. However, due to increased drainage, shrubs could profit from such changes in adjacent areas. Both climate and thaw

  6. Effects of freezing/thawing on the mechanical properties of decellularized lungs.

    Science.gov (United States)

    Nonaka, Paula N; Campillo, Noelia; Uriarte, Juan J; Garreta, Elena; Melo, Esther; de Oliveira, Luis V F; Navajas, Daniel; Farré, Ramon

    2014-02-01

    Lung bioengineering based on decellularized organ scaffolds is a potential alternative for transplantation. Freezing/thawing, a usual procedure in organ decellularization and storage could modify the mechanical properties of the lung scaffold and reduce the performance of the bioengineered lung when subjected to the physiological inflation-deflation breathing cycles. The aim of this study was to determine the effects of repeated freezing/thawing on the mechanical properties of decellularized lungs in the physiological pressure-volume regime associated with normal ventilation. Fifteen mice lungs (C57BL/6) were decellularized using a conventional protocol not involving organ freezing and based on sodium dodecyl sulfate detergent. Subsequently, the mechanical properties of the acellular lungs were measured before and after subjecting them to three consecutive cycles of freezing/thawing. The resistance (RL ) and elastance (EL ) of the decellularized lungs were computed by linear regression fitting of the recorded signals (tracheal pressure, flow, and volume) during mechanical ventilation. RL was not significantly modified by freezing-thawing: from 0.88 ± 0.37 to 0.90 ± 0.38 cmH2 O·s·mL(-1) (mean ± SE). EL slightly increased from 64.4 ± 11.1 to 73.0 ± 16.3 cmH2 O·mL(-1) after the three freeze-thaw cycles (p = 0.0013). In conclusion, the freezing/thawing process that is commonly used for both organ decellularization and storage induces only minor changes in the ventilation mechanical properties of the organ scaffold. © 2013 Wiley Periodicals, Inc.

  7. Survey of Permafrost Thaw Influence on Surface Water Dissolved Organic Matter in Sub-Arctic Alaska

    Science.gov (United States)

    Gagne, K.; Walter Anthony, K. M.; Guerard, J.

    2016-12-01

    The chemical and functional group composition of permafrost organic matter largely remains unknown. Characterizing dissolved organic matter (DOM) chemical composition offers insight into the quality and extent of the permafrost carbon pool that may mobilize and transform into smaller components or greenhouse gasses upon thaw. The Goldstream watershed in interior Alaska is underlain by discontinuous permafrost with varying stage of talik (thaw bulb) development, allowing for the comparison of thaw stage on DOM composition. Surface water samples were collected from lakes and streams in regions of the watershed with varying degrees of permafrost thaw in order to investigate seasonal variability and associated trends in DOM composition. Additionally, select permafrost cores were obtained and utilized in leachate experiments to identify the fraction and reactivity of the soil organic carbon pool leached from active layer and permafrost soil upon thaw. Leached organic moieties were compared to the total permafrost organic carbon pool and the DOM of the overlying surface water. Extracted isolates from both permafrost and active layer were characterized by 3D excitation-emission fluorescence, UV-vis spectroscopy, PARAFAC, SPR-W5-WATERGATE 1H- NMR, total organic carbon, ICP-MS, and ion chromatography, coupled with photolysis experiments to determine reactive oxygen species production to characterize potential reactivity. Differences in carbon pool composition were resolved between seasons and with the extent of permafrost thaw. This is a key first step to determine how permafrost degradation influences DOM pool composition on a molecular level, which is essential for assessing permafrost organic matter impact on biogeochemical cycling and other ecological functions as it becomes incorporated into a warming landscape.

  8. Measuring influenza RNA quantity after prolonged storage or multiple freeze/thaw cycles.

    Science.gov (United States)

    Granados, Andrea; Petrich, Astrid; McGeer, Allison; Gubbay, Jonathan B

    2017-09-01

    In this study, we aim to determine what effects prolonged storage and repeated freeze/thaw cycles have on the stability of influenza A(H1N1)pdm09 (influenza A/H1N1)RNA. Cloned influenza A/H1N1 RNA transcripts were serially diluted from 8.0-1.0 log10 copies/μl. RT-qPCR was used to measure RNA loss in transcripts stored at -80°C, -20°C, 4°C and 25°C for up to 84days or transcripts undergoing a total of 10 freeze/thaw cycles. Viral load was measured in clinical specimens stored at-80°C for three years (n=89 influenza A RNA extracts; n=35 primary specimens) and in 10 clinical specimens from the 2015/2016 influenza season that underwent 7 freeze/thaw cycles. RNA stored at -80°C, -20°C, 4°C and 25°C is stable for up to 56, 56, 21, and 7days respectively or up to 9 freeze/thaw cycles when stored at -80°C. There is no difference in viral load in clinical specimens that have been stored for up to three years at -80°C if they are re-extracted. Similarly, clinical specimens undergoing up to 7 freeze/thaw cycles are stable if they are re-extracted between cycles. Influenza specimens can be stored for up to three years at -80°C or undergo up to 7 freeze/thaw cycles without loss of RNA quantity if re-extracted. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Investigation of Freeze and Thaw Cycles of a Gas-Charged Heat Pipe

    Science.gov (United States)

    Ku, Jentung; Ottenstein, Laura; Krimchansky, Alexander

    2012-01-01

    The traditional constant conductance heat pipes (CCHPs) currently used on most spacecraft run the risk of bursting the pipe when the working fluid is frozen and later thawed. One method to avoid pipe bursting is to use a gas-charged heat pipe (GCHP) that can sustain repeated freeze/thaw cycles. The construction of the GCHP is similar to that of the traditional CCHP except that a small amount of non-condensable gas (NCG) is introduced and a small length is added to the CCHP condenser to serve as the NCG reservoir. During the normal operation, the NCG is mostly confined to the reservoir, and the GCHP functions as a passive variable conductance heat pipe (VCHP). When the liquid begins to freeze in the condenser section, the NCG will expand to fill the central core of the heat pipe, and ice will be formed only in the grooves located on the inner surface of the heat pipe in a controlled fashion. The ice will not bridge the diameter of the heat pipe, thus avoiding the risk of pipe bursting during freeze/thaw cycles. A GCHP using ammonia as the working fluid was fabricated and then tested inside a thermal vacuum chamber. The GCHP demonstrated a heat transport capability of more than 200W at 298K as designed. Twenty-seven freeze/thaw cycles were conducted under various conditions where the evaporator temperature ranged from 163K to 253K and the condenser/reservoir temperatures ranged from 123K to 173K. In all tests, the GCHP restarted without any problem with heat loads between 10W and 100W. No performance degradation was noticed after 27 freeze/thaw cycles. The ability of the GCHP to sustain repeated freeze/thaw cycles was thus successfully demonstrated.

  10. Resilience of norovirus GII.4 to freezing and thawing: implications for virus infectivity.

    Science.gov (United States)

    Richards, Gary P; Watson, Michael A; Meade, Gloria K; Hovan, Gregory L; Kingsley, David H

    2012-12-01

    Genogroup II.4 norovirus (NoV) remains the predominant NoV strain in food- and water-borne outbreaks. Capsid integrity as well as viral RNA persistence were determined for GII.4 NoV by real-time RT-PCR after 1-14 freeze/thaw (F/T) cycles (-80 °C/+22 °C) or after -80 °C storage for up to 120 days. In both cases, capsid integrity and viral RNA titers remained stable. RNase was exogenously added after 1-14 F/T cycles, but did not alter the amount of genomic NoV RNA detected, indicating that capsids remained intact. Presumptive NoV infectivity was evaluated in functional studies by a porcine gastric mucin binding assay. Viruses frozen and thawed up to 14× bound similarly to porcine mucin, suggesting no reduction in virus infectivity. Overall, this study shows that a) NoV particles retain their integrity for at least 14 F/T cycles, b) long-term (120 day) frozen storage does not decrease NoV RNA titers, and c) capsid binding to receptor-like glycoprotein moieties remains unaltered after 14 F/T cycles. This work indicates that freezing and thawing of foods or beverages would not be a practical processing intervention to reduce NoV contamination. Likewise, repeated freezing and thawing, as might be encountered during winter months, is not expected to inactivate NoV in the environment. Results do show that laboratory samples destined for molecular biological analyses or for use as positive controls may be repeatedly frozen and thawed without any anticipated reduction in NoV RNA titers. This study documents the cryostability of NoV capsids and RNA to freezing and thawing and to the possible retention of virus infectivity.

  11. Microstructure Changes in Hardened Cement Paste after Freezing – Thawing Cycles

    Directory of Open Access Journals (Sweden)

    Gintautas SKRIPKIŪNAS

    2013-03-01

    Full Text Available This article analyses the results of the freezing – thawing with deicing salt test where changes in the microstructure of the surface layer in contact with aggressive environment of hardened cement paste produced with and without sodium silicate (hereinafter NTS admixture were observed after freeze-thaw cycles in the presence of calcium chloride. After 56 cycles of freezing – thawing with deicing salt test micro-cracks and cavities were observed in the microstructure of the surface layer of hardened cement paste with and without NTS admixture. In the case of hardened cement paste with NTS admixture changes in the microstructure of the surface layer are less prominent: the number and size of cavities and micro-cracks are smaller. The test revealed that compressive stress, which before freezing – thawing with deicing salt test was very similar in hardened cement paste with and without NTS admixture (85.4 MPa and 82.8 MPa respectively, changed after 56 cycles of freezing – thawing with deicing salt test as follows: reduced by 39.5 % in concrete without NTS admixture and increased slightly (2.5 % in hardened cement paste with NTS admixture. Based on the test results the authors arrived at the conclusion that sodium silicate solution can be effectively used to extend the useful life of hardened cement paste exposed to freeze-thaw cycles and affected by CaCl2.DOI: http://dx.doi.org/10.5755/j01.ms.19.1.3835

  12. Startup thaw concept for the SP-100 space reactor power system

    Science.gov (United States)

    Kirpich, A.; Das, A.; Choe, H.; Mcnamara, E.; Switick, D.; Bhandari, P.

    1990-01-01

    A thaw concept for a space reactor power system which employs lithium as a circulant for both the heat-transport and the heat-rejection fluid loops is presented. An exemplary thermal analysis for a 100-kWe (i.e., SP-100) system is performed. It is shown that the design of the thaw system requires a thorough knowledge of the various physical states of the circulant throughout the system, both spatially and temporally, and that the design has to provide adequate margins for the system to avoid a structural or thermally induced damage.

  13. Temporal stereophotogrammetric analysis of retrogressive thaw slumps on Herschel Island, Yukon Territory

    Directory of Open Access Journals (Sweden)

    H. Lantuit

    2005-01-01

    Full Text Available The western Canadian Arctic is identified as an area of potentially significant global warming. Thawing permafrost, sea level rise, changing sea ice conditions and increased wave activity will result in accelerated rates of coastal erosion and thermokarst activity in areas of ice-rich permafrost. The Yukon Coastal Plain is widely recognized as one of the most ice-rich and thaw-sensitive areas in the Canadian Arctic. In particular, Herschel Island displays extensive coastal thermokarst. Retrogressive thaw slumps are a common thermokarst landform along the Herschel Island coast that have been increasing in both frequency and extent have in recent years due to increased thawing of massive ground ice and coastal erosion. The volume of sediment and ground ice eroded by retrogressive slump activity and the potential release of climate change related materials like organic carbon, carbon dioxide and methane are largely unknown. The remote setting of Herschel Island, and the Arctic in general, make direct observation of this type of erosion and the analysis of potential climate feedbacks extremely problematic. Remote sensing provides possibly the best solution to this problem. This study looks at two retrogressive thaw slumps located on the western shore of Herschel Island and using stereophotogrammetric methods attempts to (1 develop the first three-dimensional geomorphic analysis of this type of landform, and (2 provide an estimation of the volume of sediment/ground ice eroded through back wasting thermokarst activity. Digital Elevation Models were extracted for the years 1952, 1970 and 2004 and validated using data collected in the field using Kinematic Differential Global Positioning System. Estimates of sediment volumes eroded from retrogressive thaw slumps were found to vary greatly. In one case the total volume of material lost for the 1970–2004 period was approximately 1560000m3. The estimated volume of sediment alone was 360000m3. The

  14. Flow cytometric assessment of fresh and frozen-thawed Canada goose (Branta canadensis) semen.

    Science.gov (United States)

    Partyka, Agnieszka; Łukaszewicz, Ewa; Niżański, Wojciech

    2011-09-15

    The present study was conducted to investigate spermatozoal membrane integrity, acrosome integrity, mitochondrial activity, and chromatin structure in fresh and frozen-thawed Canada goose (Branta canadensis) semen with the use of the flow cytometry. The experiment was carried out on ten, 2-year-old, Canada goose ganders. The semen was collected twice a week, by a dorso-abdominal massage method, then pooled and subjected to cryopreservation in straws, in a programmable freezing unit with the use of dimethyloformamide (DMF) as a cryoprotectant. Frozen samples were thawed in a water bath at 60 °C. The freezing procedure was performed ten times. For the cytometric analysis the fresh and the frozen-thawed semen was extended with EK extender to a final concentration of 50 million spermatozoa per mL. Sperm membrane integrity was assessed with SYBR-14 and propidium iodide (PI), acrosomal damage was evaluated with the use of PNA-Alexa Fluor®488 conjugate, mitochondrial activity was estimated with Rhodamine 123 (R123), and spermatozoal DNA integrity was measured by the sperm chromatin structure assay (SCSA). The cryopreservation of Canada goose semen significantly decreased the percentage of live cells, from 76.3 to 50.4% (P < 0.01). Moreover, we observed the significant decrease in the percentage of live spermatozoa with intact acrosomes (P < 0.01), but we did not detect significant changes in the percentage of live spermatozoa with ruptured acrosomes. However, after thawing 50% of Canada goose live spermatozoa retained intact acrosomes. Furthermore, the percentage of live spermatozoa with active mitochondria was significantly lower in the frozen-thawed semen than in the fresh semen (P < 0.05). Nevertheless, after thawing the mitochondria remained active in almost 50% of live cells. In the present study, we observed no changes in the percentage of sperm with fragmented DNA after freezing-thawing of Canada goose semen. In conclusion, the present study indicates that even

  15. Effect of Different Straw Volumes and Thawing Rates on Post-Thaw Quality and Fertilization Ability of Cryopreserved Common Carp (Cyprinus carpio Sperm

    Directory of Open Access Journals (Sweden)

    İlker YAVAŞ

    2017-04-01

    Full Text Available Cryopreservation of sperm cells is an essential process applied for long-term conservation of aquatic genetic resources. The goal of this research was to determine effect different of straws volumes and thawing rates on the post-thaw quality and fertilization ability of cryopreserved common carp (Cyprinus carpio sperm. In this study, semen was cryopreserved according to conventional slow freezing protocol. For this aim, the cryosolution contained 75 mM NaCl, 70 mM KCl, 2 mM CaCl2, 1 mM MgSO4 and 20 mM Tris (pH: 8 supplemented with 10% MeOH. Following equilibration at +4°C for 10 min, semen was packed into 0.25, 0.5 and 1.5 mL straws and frozen in liquid nitrogen vapour (for 10 min at -120ºC and finally stored in liquid nitrogen (-196ºC tank. Thawing of cryopreserved semen process was performed at 30ºC for 10, 20 and 30 seconds in a water bath. Fertilization was performed using ratio of 1x105 spermatozoa/egg. The highest fertility (68.4±2.5% was determined with cryopreserved sperm packed in 1.5 mL straws that thawed at 30ºC for 30 s. According to the results of this research, sperm cryopreserved with ionic extender containing 10% methanol and packed in 1.5 mL straws are suitable to achieve high fertilization of common carp eggs.

  16. Non-invasive viability assessment of day-4 frozen-thawed human embryos using near infrared spectroscopy

    NARCIS (Netherlands)

    Vergouw, C.G.; Botros, L.L.; Judge, K.; Henson, M.; Roos, P.; Kostelijk, E.H.; Schats, R.; Twisk, J.W.; Hompes, P.G.A.; Sakkas, D.; Lambalk, C.B.

    2011-01-01

    This study investigated if metabolomic profiling of culture media using near infrared (NIR) spectroscopy was related to live-birth rates after single-embryo transfer of frozen-thawed embryos. Analysis of culture media of frozen-thawed embryos was performed by NIR spectroscopy. A viability score was

  17. Effect of sucrose and pectin addition on physical, chemical, thermal and rheological properties of frozen/thawed pineapple pulps

    Science.gov (United States)

    Conceição, Márcia Cavalcante; Fernandes, Tatiana Nunes; Prado, Mônica Elisabeth Torres; de Resende, Jaime Vilela

    2012-09-01

    Pectin (0-1.0 g/100 mL) and sucrose (0-20 g/100 mL) were added to pineapple pulp to improve their rheological properties, thermal properties and stability after freezing and thawing processes. The properties of the mixes were characterized before and after freezing and thawing. Samples were frozen at -20°C, and the freeze concentration was evaluated every 60 min. The thawing rate was evaluated at 19°C and quantified by photographic editing and image analysis software. The thawing rates and values for the freeze concentration were leveled out at pectin concentrations above 0.5 g/100 mL pectin, which indicated that pectin functions to maintain structural homogeneity during freezing. In the thawed samples, the plastic viscosity values were leveled out from pectin concentrations (0.25-0.75 g/100 mL) as the sucrose concentration increased when compared to unfrozen samples. The differences between the rheological parameters of the unfrozen and frozen/thawed pulps, the higher yield stress values after thawing were attributed to the size of suspended particles in the pulp. Applications can specify formulations of frozen products containing pectin, where these properties can be handled after thawing the product.

  18. Creep characteristics and process analyses of a thaw slump in the permafrost region of the Qinghai-Tibet Plateau, China

    Science.gov (United States)

    Sun, Zhe; Wang, Yibo; Sun, Yan; Niu, Fujun; Li, Guoyu; Gao, Zeyong

    2017-09-01

    A thaw slump in the permafrost region of the Qinghai-Tibet Plateau was monitored to investigate typical characteristics of creep positions and processes in combination with soil property analyses. The results show that the thaw settlement exhibits a contraction effect in the horizontal direction because of uneven thaw settlement. Slope displacement of creep occurs only in the top 50 cm of the soil. The gravimetric water content, soil porosity, and soil temperature are higher near the thaw slump in thaw seasons compared with the undisturbed soil; however, the shear strength is lower. Melting ground ice releases thaw water that converges along the slope and forms an overland flow at the front part of the gentle slope area and a ponding depression at the slope bottom. The analyses of slope stability using the infinite slope model shows that the headwall of the slope is inevitably unstable and slides under saturated conditions, whereas the gentle slope area and slope bottom with slight creep displacement are relatively stable. The small retrogressive thaw slump is in an early development stage. With increasing degree of thaw settlement and rate of erosion, the headwall will become steeper and a thermokarst lake will form at the slope bottom.

  19. Experimentally increased nutrient availability at the permafrost thaw front selectively enhances biomass production of deep-rooting subarctic peatland species

    NARCIS (Netherlands)

    Keuper, Frida; Dorrepaal, Ellen; van Bodegom, Peter M.; van Logtestijn, Richard; Venhuizen, Gemma; van Hal, Jurgen; Aerts, Rien

    2017-01-01

    Climate warming increases nitrogen (N) mineralization in superficial soil layers (the dominant rooting zone) of subarctic peatlands. Thawing and subsequent mineralization of permafrost increases plant-available N around the thaw-front. Because plant production in these peatlands is N-limited, such

  20. Investigation of the impact of nanotechnology on the freeze-thaw durability of concrete containing d-cracking aggregates.

    Science.gov (United States)

    2015-05-01

    Freezing and thawing damage is the most common cause of distress in Kansas pavements. Many : locally available aggregates in Kansas do not meet current standards for use in concrete pavements because : of poor freeze-thaw durability. The use of nanot...

  1. Freeze-Thaw Resistance of Normal and High Strength Concretes Produced with Fly Ash and Silica Fume

    Directory of Open Access Journals (Sweden)

    Cenk Karakurt

    2015-01-01

    Full Text Available This study is based on determination of the freeze-thaw resistance of air-entrained and non-air-entrained normal strength concrete (NC and high strength concrete (HSC produced with fly ash and silica fume according to surface scaling. The procedure allows us to measure the amount of scaling per unit surface area due to a number of well defined freezing and thawing cycles in the presence of deicing salt. The weight loss, surface scaling, moisture uptake, and internal damage were measured after 0 and after every 4th freeze-thaw cycle. The test results showed that the freeze-thaw resistance is influenced directly by the compressive strength property of the concrete. Silica fume significantly reduced the resistance of normal strength concrete against freeze-thaw effect without plasticizing agent. The surface scaling of silica fume concrete without admixture was 22% higher than reference normal concrete.

  2. In vitro blastocyst development of post-thaw vitrified bovine oocytes

    Directory of Open Access Journals (Sweden)

    D. J. Dutta,

    2013-08-01

    Full Text Available Aim: To evaluate the developmental competence of post-thaw vitrified bovine cumulus-oocyte complexes (COCs in vitro.Materials and Methods: A total of 129 COCs were cryopreserved using vitrification solution comprising of 15% ethylene glycol (EG + 15% dimethyl sulfoxide (DMSO + 0.6 M sucrose in medium TCM-199 with 10% FBS. Immediately, within a minute they are plunged into liquid nitrogen using 0.25 ml straws. Thawing was made with a step wise dilution method. Post-thaw normal vitrified and non-vitrified oocytes were subjected to in vitro maturation and in vitro fertilization.Results: Post-thaw survival percentage of vitrified oocytes was 88.37% and maturation performance of vitrified oocytes on the basis of cumulus expansion was 81.58% as compared to non-vitrified control 93.85%. The in vitro fertilization performance of vitrified oocytes was 49.46% as compared to the non-vitrified ones (63.11%. Similarly, blastocyst formation of vitrified oocytes was 21.74% as compared to 32.47% in non-vitrified oocytes.Conclusion: Vitrification of immature bovine oocytes using 7.5% EG + 7.5% DMSO for equilibration and 15% EG +15% DMSO + 0.6 M sucrose as vitrification solution yielded better in vitro fertilization and blastocyst formation rate.

  3. Computer Simulation and Optimization of the Process of Thawing of Grounds Using Microwave Energy

    Science.gov (United States)

    Nekrasov, S. A.; Volkov, V. S.

    2017-01-01

    In this article, consideration is given to a mathematical model and a numerical method to calculate and optimize the process of high-speed thawing of grounds using microwave energy. Relevant examples of calculations and an analysis of results are presented.

  4. The effect of two packaging systems on the post-thaw characteristics of canine sperm.

    Science.gov (United States)

    Strzeżek, R; Polakiewicz, P; Kordan, W

    2015-01-01

    The aim of this study was to compare the effect of different packaging systems on some parameters of cryopreserved canine spermatozoa. The experimental material consisted of the sperm-rich fractions of ejaculates collected from four Beagle dogs. Semen samples for cryopreservation were stored in 0.25 ml plastic straws and two aluminum tubes with a total volume of 5.0 ml. Semen was frozen in static nitrogen vapor for 10 minutes (0.25 ml straws) or 15 and 20 minutes (aluminum tubes). Post-thaw assessments involved the determination of sperm motility parameters using a computer assisted sperm analyzer (CASA), sperm plasma membrane integrity (SPMI), mitochondrial membrane potential (MMP) and acrosome integrity (normal apical ridge, NAR). Regardless of the packaging system applied, no significant differences in total sperm motility (TMOT) or selected kinematic parameters were observed after freezing-thawing. However, spermatozoa frozen in 0.25 mL straws were characterized by improved functionality, in particular mitochondrial function, after thawing. The results indicate that large quantities of canine semen can be frozen in aluminum tubes. Further studies are required, however, to evaluate different freezing and thawing rates of aluminum tubes.

  5. The effects of freezing, storage, and thawing on cell compartment integrity and ultrastructure

    DEFF Research Database (Denmark)

    Prentø, P

    1997-01-01

    The effects of slow freezing and thawing on enzyme compartmentalization and ultrastructure were studied in rat liver slices frozen in dry ice, isopentane/ethanol-dry ice, or liquid nitrogen, and stored at -80 degrees C for 1-14 days. Non-frozen slices served as controls. Frozen liver slices were...

  6. Stability after thawing of RBCs frozen with the high- and low-glycerol method

    NARCIS (Netherlands)

    Lelkens, Charles C. M.; Noorman, Femke; Koning, Jack G.; Truijens-de Lange, Rosa; Stekkinger, Perry S.; Bakker, Joa C.; Lagerberg, Johan W. M.; Brand, Anneke; Verhoeven, Arthur J.

    2003-01-01

    BACKGROUND: RBCs can be frozen with either the high-glycerol method (HGM) or the low-glycerol method (LGM). To date, the use of frozen RBCs is hampered by a 24-hour outdating period after thawing. A closed washing system (ACP 215) may solve this problem. STUDY DESIGN AND METHODS: We compared the

  7. Effect of cooling on sperm motility before and after frozen-thawed ...

    African Journals Online (AJOL)

    The aim of this study was to assess the effect of cooling on sperm motility before and after frozen-thawed stallion semen. Fifteen ejaculates of three stallions were collected with artificial vagina. The progressive motility was determined under microscope immediately after collection, cooling (5°C for 0, 2, 7 or 24 h) before ...

  8. Salt crystallization and freeze-thaw damage of repair mortars and porous limestone; a laboratory perspective

    Science.gov (United States)

    Szemerey-Kiss, Balázs; Török, Ákos

    2017-04-01

    Durability of porous limestone and repair mortars were tested parallel. The specimens were subjected to salt weathering and freeze-thaw to understand the coeval behaviour and adherence of these materials. The tests were evaluated according to European Norms, salt crystallization (EN 12370) and freeze-thaw resistance (EN 12371). Three types of commercial available repair mortars and four types of laboratory mixed mortars were used for the tests. A Miocene porous limestone was also tested 40x40x40mm in size. 18 different mortars were placed next to limestone cubes in the 40x40x160mm stainless steel moulds (4 in one mould). Another 30 samples were prepared as control ones. Adhesion between the limestone and repair mortars reduced due to external stresses (freeze-thaw, salt). The results clearly show that durability of commercially available repair mortars is higher than that of the laboratory mixed mortars. Significant differences between the damage caused by freeze-thaw and salt crystallization cycles were recorded. Commercial available mortars have shown stronger adhesion during the tests. Most of the commercial samples kept the contact with the limestone interface until the end of the cyclic tests (30th cycle). At the same time, laboratory mixed mortars detached earlier (after the 8th cycle). Commercial mortars with 50m% limestone aggregate showed decreased durability, since detachment was observed after the 23rd cycle. The financial support of NKFI Fund (ref. no. K 116532) is appreciated.

  9. Gelatin-Filtered Consomme: A Practical Demonstration of the Freezing and Thawing Processes

    Science.gov (United States)

    Lahne, Jacob B.; Schmidt, Shelly J.

    2010-01-01

    Freezing is a key food processing and preservation technique widely used in the food industry. Application of best freezing and storage practices extends the shelf-life of foods for several months, while retaining much of the original quality of the fresh food. During freezing, as well as its counterpart process, thawing, a number of critical…

  10. Aggregate Freezing-Thawing Performance Using the Iowa Pore Index : final report.

    Science.gov (United States)

    2016-10-01

    In cold climates, the use of non-durable aggregate leads to premature pavement deterioration due to damage caused by freezing-thawing cycles. Differentiating durable and non-durable aggregates is a crucial yet challenging task. The frost durability o...

  11. Basidiomycete cultures on perlite survive successfully repeated freezing and thawing in cryovials without subculturing.

    Science.gov (United States)

    Homolka, Ladislav; Lisá, Ludmila; Nerud, Frantisek

    2007-06-01

    Mycelial basidiomycete cultures on perlite in cryovials survived successfully three successive cycles of freezing, storage in liquid nitrogen (LN) and thawing without noticeable changes. This indicates that using perlite as a carrier for cryopreservation could in most cases overcome difficulties caused by interrupted supply of LN or electric power during the storage. Cultures on perlite can also be reused for successive inoculations.

  12. Measuring thermal conductivity in freezing and thawing soil using the soil temperature response to heating

    NARCIS (Netherlands)

    Overduin, P.; Kane, D.L.; Loon, van W.K.P.

    2006-01-01

    The thermal conductivity of the thin seasonally freezing and thawing soil layer in permafrost landscapes exerts considerable control over the sensitivity of the permafrost to energy and mass exchanges at the surface. At the same time, the thermal conductivity is sensitive to the state of the soil,

  13. Response of CO2 exchange in a tussock tundra ecosystem to permafrost thaw and thermokarst development

    Science.gov (United States)

    Jason Vogel; Edward A.G. Schuur; Christian Trucco; Hanna. Lee

    2009-01-01

    Climate change in high latitudes can lead to permafrost thaw, which in ice-rich soils can result in ground subsidence, or thermokarst. In interior Alaska, we examined seasonal and annual ecosystem CO2 exchange using static and automatic chamber measurements in three areas of a moist acidic tundra ecosystem undergoing varying degrees of permafrost...

  14. The effect of quercetin on fertility of frozen-thawed ram epididymal ...

    African Journals Online (AJOL)

    The aim of the present study was to evaluate the effects of quercetin as an antioxidant supplement on frozen-thawed ram epididymal sperm quality. Quercetin is a type of flavonoid antioxidant that is found in plants, with the ability to scavenge free radicals. Twenty testicles from mature rams were collected from a nearby ...

  15. Colour Changes in Meat of Foals as Affected by Slaughtering Age and Post-thawing Time

    Directory of Open Access Journals (Sweden)

    P. De Palo

    2012-12-01

    Full Text Available The aim of the present work was to investigate how colour changes of foal meat can vary after thawing out in relation to the slaughtering age of the horses and to the post-thawing time. Eighteen Italian Heavy Draught Horse (IHDH foals were used for the trial. They were subdivided in three groups according to their slaughtering age (6, 11 and 18 months. Two different surfaces were investigated for each sample: a fresh cut surface (daily renewed cutting surface: DRCS, and not-renewed cutting surface (NRCS. The redness of both investigated surfaces increased with slaughtering age (p<0.01. Moreover, this parameter decreased during post-thawing time (p<0.01 only on the NRCS, probably due to the myoglobin oxidation processes. Colour is an important visual cue denoting perceived quality by consumers. So, by a chromatic perspective the thawed meat of IHDH foals slaughtered at 6 and 11 months proved to be that which best meets the market requirements.

  16. Analysis of Different Freezing/Thawing Parameterizations using the UTOPIA Model

    Directory of Open Access Journals (Sweden)

    Claudio Cassardo

    2010-08-01

    Full Text Available Soil moisture changes are generally due to external factors (precipitation, evaporation, etc. and internal forces (gravitational force, capillarity, transpiration, etc.. When soil temperatures remain below 0 °C for a long time (hours or even entire consecutive days, part of the liquid water content of the soil can freeze, thus freezing/thawing effects must be taken into account in those conditions. The present work is devoted to the numerical modeling of the water phase change in the soil. The model used in this study for the land surface processes is UTOPIA (University of TOrino land Process Interaction in Atmosphere model, which is the updated version of LSPM (Land Surface Process Model. Scientific literature proposes some formulations to account for freezing/thawing processes. Three different parameterizations have been compared using a synthetic dataset in order to assess which one performs best from a physical point of view. Parameterizing freezing/thawing processes creates numerical instability and water overproduction in the UTOPIA model. These problems have been solved and described in the paper by means of synthetic data created to test the new parameterizations. The results show that UTOPIA is able to capture the freezing/thawing physical processes.

  17. EFFECT OF FREEZE-THAW ON THE HYDRAULIC CONDUCTIVITY OF BARRIER MATERIALS: LABORATORY AND FIELD EVALUATION

    Science.gov (United States)

    Laboratory tests were conducted on barrier materials to determine if their hydraulic conductivity changes as a result of freezing and thawing. esults of the tests were compared to data collected from a field study. ests were conducted on two compacted clays, one sand-bentonite mi...

  18. Repeated freeze-thaw cycle effects on soil compaction in a clay loam in northeastern Montana

    Science.gov (United States)

    In recent years, there has been an increased global concern regarding the impact of soil compaction on crop production and soil quality in modern mechanized agricultural farming systems. Freeze-thaw processes influence the physical properties of soil, primarily soil compaction and structure. A 3-yr...

  19. Efficient encapsulation of plasmid DNA in anionic liposomes by a freeze/thaw extrusion procedure

    NARCIS (Netherlands)

    Schoen, P; Bijl, L; Wilschut, J

    1998-01-01

    In this study we investigated whether intact plasmid DNA can be efficiently encapsulated in anionic liposomes prepared by freeze/thaw and extrusion techniques. There is controversy about this method of DNA encapsulation, especially as to whether DNA remains intact and retains its biological activity

  20. Effect of Fast Freeze-Thaw Cycles on Mechanical Properties of Ordinary-Air-Entrained Concrete

    Directory of Open Access Journals (Sweden)

    Huai-shuai Shang

    2014-01-01

    Full Text Available Freezing-thawing resistance is a very significant characteristic for concrete in severe environment (such as cold region with the lowest temperature below 0°C. In this study, ordinary-air-entrained (O-A-E concrete was produced in a laboratory environment; the compressive strength, cubic compressive strength of C50, C40, C30, C25, and C20 ordinary-air-entrained concrete, tensile strength, and cleavage strength of C30 ordinary-air-entrained concrete were measured after fast freeze-thaw cycles. The effects of fast freeze-thaw cycles on the mechanical properties (compressive strength and cleavage strength of ordinary-air-entrained concrete materials are investigated on the basis of the experimental results. And the concise mathematical formula between mechanical behavior and number of fast freeze-thaw cycles was established. The experiment results can be used as a reference in design, maintenance, and life prediction of ordinary-air-entrained concrete structure (such as dam, offshore platform, etc. in cold regions.

  1. Orally administered Chrysin improves post-thawed sperm quality and fertility of rooster.

    Science.gov (United States)

    Zhandi, M; Ansari, M; Roknabadi, P; Zare Shahneh, A; Sharafi, M

    2017-12-01

    Chrysin is a bioflavonoid compound found in passion flower, chamomile, propolis and honey at high levels. Post-thawed sperm quality and fertility of Chrysin-fed roosters were assessed in this study. Twenty 40-week-old male broiler breeders were randomly divided into four groups and fed basal diet supplemented with different levels of Chrysin including 0 (Ch-0), 25 (Ch-25), 50 (Ch-50) or 75 (Ch-75) mg/day for 12 consecutive weeks. Semen samples were weekly collected from 6th to 9th week of experiment to evaluate some sperm quality parameters including total and progressive motility, plasma membrane integrity and functionality (in fresh and post-thawed samples) and mitochondrial activity (only in post-thawed samples). Also, collected semen samples from 10th, 11th and 12th week of experiment were frozen and then artificially inseminated to test fertility rate. According to the results, an improvement in both fresh and post-thawed sperm quality including total [fresh: 88.00 ± 0.58 and 87.25 ± 0.67 (p cryopreservation-induced impairment of sperm quality and fertility rate. © 2017 Blackwell Verlag GmbH.

  2. Physiological responses of planting frozen and thawed Douglas-fir seedlings

    Science.gov (United States)

    M. Anisul Islam; Kent G. Apostol; Douglass F. Jacobs; R. Kasten Dumroese

    2008-01-01

    We studied the short-term (7-day) physiological responses of planting thawed and frozen root plugs of Douglas-fir (Pseudotsuga menziesii) seedlings in 2 separate experiments under cool-moist and warm-dry growing conditions, respectively. Our results showed that shoot water potential, root hydraulic conductance, net photosynthesis (A), and...

  3. The Effect of Freeze-Thaw Conditions on Arctic Soil Bacterial Communities

    Directory of Open Access Journals (Sweden)

    Virginia K. Walker

    2013-02-01

    Full Text Available Climate change is already altering the landscape at high latitudes. Permafrost is thawing, the growing season is starting earlier, and, as a result, certain regions in the Arctic may be subjected to an increased incidence of freeze-thaw events. The potential release of carbon and nutrients from soil microbial cells that have been lysed by freeze-thaw transitions could have significant impacts on the overall carbon balance of arctic ecosystems, and therefore on atmospheric CO2 concentrations. However, the impact of repeated freezing and thawing with the consequent growth and recrystallization of ice on microbial communities is still not well understood. Soil samples from three distinct sites, representing Canadian geographical low arctic, mid-arctic and high arctic soils were collected from Daring Lake, Alexandra Fjord and Cambridge Bay sampling sites, respectively. Laboratory-based experiments subjected the soils to multiple freeze-thaw cycles for 14 days based on field observations (0 °C to −10 °C for 12 h and −10 °C to 0 °C for 12 h and the impact on the communities was assessed by phospholipid fatty acid (PLFA methyl ester analysis and 16S ribosomal RNA gene sequencing. Both data sets indicated differences in composition and relative abundance between the three sites, as expected. However, there was also a strong variation within the two high latitude sites in the effects of the freeze-thaw treatment on individual PLFA and 16S-based phylotypes. These site-based heterogeneities suggest that the impact of climate change on soil microbial communities may not be predictable a priori; minor differential susceptibilities to freeze-thaw stress could lead to a “butterfly effect” as described by chaos theory, resulting in subsequent substantive differences in microbial assemblages. This perspectives article suggests that this is an unwelcome finding since it will make future predictions for the impact of on-going climate change on soil

  4. The Effect of Thawing Temperature on Sperm Quality of Friesian Holstein Bulls

    Directory of Open Access Journals (Sweden)

    Tri Utami

    2014-11-01

    Full Text Available The percentage of sperm motility and morphology are important criteria in evaluating the quality of sperm before it is used for artificial insemination (AI. This study was conducted to observe post thawing motility and abnormal morphology of spermatozoa Friesian Holstein (FH. The materials were used 10 straws of FH bulls in the form of 0.25 ml. A total of 10 straws then divided into two treatment groups of  thawing  in water at 37°C and water 8°C, respectively. An examination of the motility and morphology of spermatozoa abnormalities performed every two hours for two times. Calculating the percentage of sperm motility was done by calculating the percentage of spermatozoa moving forward in the field of view under a microscope with a magnification of 10x. the percentage of abnormal spermatozoa was  assessed by William's stain. Spermatozoa morphology was observed by using a microscope magnification of 100x. Abnormalities of spermatozoa were calculated from a total of 200 spermatozoa, either normal or abnormal. At the same thawing time, the motility of FH cattle sperms post thawing in water temperature 37°C had a higher preference than that of post thawing in water temperature 8°C, although it was not significantly different (P > 0.05.  Based on morphological aspects, frozen semen used in this study is within the tolerance limit for the total percentage of abnormal sperm morphology between 12% to 23% and normal morphology between 70% to 88%.

  5. The impacts of recent permafrost thaw on land-atmosphere greenhouse gas exchange

    Science.gov (United States)

    Hayes, Daniel J.; Kicklighter, David W.; McGuire, A. David; Chen, Min; Zhuang, Qianlai; Yuan, Fengming; Melillo, Jerry M.; Wullschleger, Stan D.

    2014-01-01

    Permafrost thaw and the subsequent mobilization of carbon (C) stored in previously frozen soil organic matter (SOM) have the potential to be a strong positive feedback to climate. As the northern permafrost region experiences as much as a doubling of the rate of warming as the rest of the Earth, the vast amount of C in permafrost soils is vulnerable to thaw, decomposition and release as atmospheric greenhouse gases. Diagnostic and predictive estimates of high-latitude terrestrial C fluxes vary widely among different models depending on how dynamics in permafrost, and the seasonally thawed 'active layer' above it, are represented. Here, we employ a process-based model simulation experiment to assess the net effect of active layer dynamics on this 'permafrost carbon feedback' in recent decades, from 1970 to 2006, over the circumpolar domain of continuous and discontinuous permafrost. Over this time period, the model estimates a mean increase of 6.8 cm in active layer thickness across the domain, which exposes a total of 11.6 Pg C of thawed SOM to decomposition. According to our simulation experiment, mobilization of this previously frozen C results in an estimated cumulative net source of 3.7 Pg C to the atmosphere since 1970 directly tied to active layer dynamics. Enhanced decomposition from the newly exposed SOM accounts for the release of both CO2 (4.0 Pg C) and CH4 (0.03 Pg C), but is partially compensated by CO2 uptake (0.3 Pg C) associated with enhanced net primary production of vegetation. This estimated net C transfer to the atmosphere from permafrost thaw represents a significant factor in the overall ecosystem carbon budget of the Pan-Arctic, and a non-trivial additional contribution on top of the combined fossil fuel emissions from the eight Arctic nations over this time period.

  6. Impact of Freezing and Thawing on Soil Oxygen Dynamics and Nutrient Fluxes

    Science.gov (United States)

    Milojevic, T.; Rezanezhad, F.; Van Cappellen, P.; Smeaton, C. M.; Parsons, C. T.

    2015-12-01

    Freeze-thaw cycles (FTCs) influence the physical properties, microbial activity, biogeochemistry, nutrient and carbon cycling in soils, and regulate subsurface oxygen (O2) availability, affecting greenhouse gas exchanges between soils and the atmosphere. The ability to monitor changes in O2 levels, which are indicative of aerobic and anaerobic conditions, is key to understanding how changes in the frequency and amplitude of freeze-thaw cycles affect a soil's geochemical conditions and microbial activity. In this study, a highly instrumented soil column experiment was designed to accurately simulate freeze-thaw dynamics under controlled conditions. This design allowed us to reproduce realistic, time- and depth-dependent temperature gradients in the soil column. Continuous O2 levels throughout the soil column were monitored using high-resolution, luminescence-based, Multi Fiber Optode (MuFO) microsensors. Image-processing techniques were used to convert light intensity of high-resolution digital images of the sensor-emitted light into O2 concentrations. Water samples from various depths in the column were collected to monitor pore water composition changes. Headspace gas measurements were used to derive the effluxes of CO2 and CH4 during the experiment. The results indicate that the pulse of oxygen introduced by thawing caused partial and temporal oxidation of previously reduced sulfur and nitrogen species, leading to concomitant changes in pore water SO42- and NO3- concentrations. Pulsed CO2 emission to the headspace was observed at the onset of thawing, indicating that a physical ice barrier had formed during frozen conditions and prevented gas exchange between the soil and atmosphere. CO2 emission was due to a combination of the physical release of gases dissolved in pore water and entrapped below the frozen zone and changing microbial respiration in response to electron acceptor variability (O2, NO3-, SO42-).

  7. Impact of Freeze/Thaw Process on Drug Substance Storage of Therapeutics.

    Science.gov (United States)

    Rayfield, William J; Kandula, Sunitha; Khan, Heera; Tugcu, Nihal

    2017-08-01

    The storage of drug substance at subzero temperatures mitigates potential risks associated with liquid storage, such as degradation and shipping stress, making it the best solution for long-term storage. However, slower (generally uncontrolled) rates of freezing and thawing of drug substance in conventional large storage containers (>2L) can lead to greater cryoconcentration (exclusion of solute molecules) resulting in zones of higher protein and excipient concentrations and changes to the desired formulation pH and excipient concentration. These conditions can negatively impact product quality, thus changing the target product profile. Freeze/thaw studies can provide valuable knowledge on the molecule even when performed from an early formulation image. This study attempts to provide guidance and strategy for planning of drug substance freeze and thaw studies in early development using a scale-down model, evaluating the impact of the (1) freeze/thaw rate, (2) mode of freezing, (3) drug substance container, (4) drug substance concentration, and (5) formulation on the drug substance product quality. Data presented in this study showed no impact on drug substance product quality after undergoing the typical one freeze/thaw cycle process for the variables evaluated. These findings suggest that a qualified scale-down model is not required for early phases of process development and that existing small-scale models can be used for drug substance storage development studies. Based on our experience, a workflow is suggested with minimal experimental design to reduce the material requirement by >70% at early stages of product development to reduce constraints. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  8. Diurnal Freeze-Thaw Cycles Modify Winter Soil Respiration in a Desert Shrub-Land Ecosystem

    Directory of Open Access Journals (Sweden)

    Peng Liu

    2016-07-01

    Full Text Available Winter soil respiration (Rs is becoming a significant component of annual carbon budgets with more warming in winter than summer. However, little is known about the controlling mechanisms of winter Rs in dryland. We made continuous measurements of Rs in four microsites (non-crust (BS, lichen (LC, moss (MC, and a mixture of moss and lichen (ML in a desert shrub-land ecosystem northern China, to investigate the causes of Rs dynamics in winter. The mean winter Rs ranged from 0.10 to 0.17 µmol CO2 m−2·s−1 across microsites, with the highest value in BS. Winter Q10 (known as the increase in respiration rate per 10 °C increase in temperature values (2.8–19 were much higher than those from the growing season (1.5. Rs and Q10 were greatly enhanced in freeze-thaw cycles compared to frozen days. Diurnal patterns of Rs between freeze-thaw and frozen days differed. Although the freeze-thaw period was relatively short, its cumulative Rs contributed significantly to winter Rs. The presence of biocrust might induce lower temperature, thus having fewer freeze-thaw cycles relative to bare soil, leading to the lower Rs for microsites with biocrusts. In conclusion, winter Rs in drylands was sensitive to soil temperature (Ts and Ts-induced freeze-thaw cycles. The temperature impact on Rs varied among soil cover types. Winter Rs in drylands may become more important as the climate is continuously getting warmer.

  9. Experimentally increased nutrient availability at the permafrost thaw front selectively enhances biomass production of deep-rooting subarctic peatland species.

    Science.gov (United States)

    Keuper, Frida; Dorrepaal, Ellen; van Bodegom, Peter M; van Logtestijn, Richard; Venhuizen, Gemma; van Hal, Jurgen; Aerts, Rien

    2017-10-01

    Climate warming increases nitrogen (N) mineralization in superficial soil layers (the dominant rooting zone) of subarctic peatlands. Thawing and subsequent mineralization of permafrost increases plant-available N around the thaw-front. Because plant production in these peatlands is N-limited, such changes may substantially affect net primary production and species composition. We aimed to identify the potential impact of increased N-availability due to permafrost thawing on subarctic peatland plant production and species performance, relative to the impact of increased N-availability in superficial organic layers. Therefore, we investigated whether plant roots are present at the thaw-front (45 cm depth) and whether N-uptake ((15) N-tracer) at the thaw-front occurs during maximum thaw-depth, coinciding with the end of the growing season. Moreover, we performed a unique 3-year belowground fertilization experiment with fully factorial combinations of deep- (thaw-front) and shallow-fertilization (10 cm depth) and controls. We found that certain species are present with roots at the thaw-front (Rubus chamaemorus) and have the capacity (R. chamaemorus, Eriophorum vaginatum) for N-uptake from the thaw-front between autumn and spring when aboveground tissue is largely senescent. In response to 3-year shallow-belowground fertilization (S) both shallow- (Empetrum hermaphroditum) and deep-rooting species increased aboveground biomass and N-content, but only deep-rooting species responded positively to enhanced nutrient supply at the thaw-front (D). Moreover, the effects of shallow-fertilization and thaw-front fertilization on aboveground biomass production of the deep-rooting species were similar in magnitude (S: 71%; D: 111% increase compared to control) and additive (S + D: 181% increase). Our results show that plant-available N released from thawing permafrost can form a thus far overlooked additional N-source for deep-rooting subarctic plant species and increase their

  10. Influence of Rapid Freeze-Thaw Cycling on the Mechanical Properties of Sustainable Strain-Hardening Cement Composite (2SHCC

    Directory of Open Access Journals (Sweden)

    Seok-Joon Jang

    2014-02-01

    Full Text Available This paper provides experimental results to investigate the mechanical properties of sustainable strain-hardening cement composite (2SHCC for infrastructures after freeze-thaw actions. To improve the sustainability of SHCC materials in this study, high energy-consumptive components—silica sand, cement, and polyvinyl alcohol (PVA fibers—in the conventional SHCC materials are partially replaced with recycled materials such as recycled sand, fly ash, and polyethylene terephthalate (PET fibers, respectively. To investigate the mechanical properties of green SHCC that contains recycled materials, the cement, PVA fiber and silica sand were replaced with 10% fly ash, 25% PET fiber, and 10% recycled aggregate based on preliminary experimental results for the development of 2SHCC material, respectively. The dynamic modulus of elasticity and weight for 2SHCC material were measured at every 30 cycles of freeze-thaw. The effects of freeze-thaw cycles on the mechanical properties of sustainable SHCC are evaluated by conducting compressive tests, four-point flexural tests, direct tensile tests and prism splitting tests after 90, 180, and 300 cycles of rapid freeze-thaw. Freeze-thaw testing was conducted according to ASTM C 666 Procedure A. Test results show that after 300 cycles of freezing and thawing actions, the dynamic modulus of elasticity and mass loss of damaged 2SHCC were similar to those of virgin 2SHCC, while the freeze-thaw cycles influence mechanical properties of the 2SHCC material except for compressive behavior.

  11. High survival of mouse embryos after rapid freezing and thawing inside plastic straws with 1-2 propanediol as cryoprotectant.

    Science.gov (United States)

    Renard, J P; Babinet, C

    1984-06-01

    A method for obtaining a high survival rate of frozen-thawed mouse embryos is presented. Eight-cell mouse embryos were frozen inside small plastic straws in the presence of 1-2 propanediol and stored at -196 C. After thawing, the embryos were diluted for only 5 min in a 1.0 M sucrose solution to remove the 1-2 propanediol from the cells. At high rate of thawing (is equivalent to 2500 C/min) more than 88% of the embryos survived in vitro to the blastocyst stage provided that the dilution of propanediol was performed rapidly during thawing. At a lower rate of thawing (is equivalent to 300 C/min), survival tended to be higher (94.7%) when dilution was done 5 min after thawing. When the frozen-thawed embryos were transferred to the oviducts of day 1 pseudopregnant recipients either directly after the dilution of 1-2 propanediol or after 24 or 48 hr of culture, a high proportion of them (65.9%) develop normally to viable fetuses.

  12. Dispersion Stability of O/W Emulsions with Different Oil Contents Under Various Freezing and Thawing Conditions.

    Science.gov (United States)

    Katsuki, Kazutaka; Miyagawa, Yayoi; Nakagawa, Kyuya; Adachi, Shuji

    2017-07-01

    Freezing and thawing of oil-in-water (O/W) emulsion-type foods bring about oil-water separation and deterioration; hence, the effects of freezing and thawing conditions on the destabilization of O/W emulsions were examined. The freezing rate and thawing temperature hardly affected the stability of the O/W emulsion. O/W emulsions having different oil fractions were stored at temperatures ranging from -30 to -20 °C and then thawed. The stability after thawing depended on the storage temperature, irrespective of the oil fraction of the emulsion. A good correlation was found between the time at which the stability began to decrease and the time taken for the oil to crystalize. These results indicated that the dominant cause for the destabilization of the O/W emulsion during freezing and thawing is the crystallization of the oil phase and that the effects of the freezing and thawing rates on the stability are insignificant. © 2017 Institute of Food Technologists®.

  13. Is there a relationship between the chromatin status and DNA fragmentation of boar spermatozoa following freezing-thawing?

    Science.gov (United States)

    Fraser, L; Strzezek, J

    2007-07-15

    In this study a radioisotope method, which is based on the quantitative measurements of tritiated-labeled actinomycin D ((3)H-AMD) incorporation into the sperm nuclei ((3)H-AMD incorporation assay), was used to assess the chromatin status of frozen-thawed boar spermatozoa. This study also tested the hypothesis that frozen-thawed spermatozoa with altered chromatin were susceptible to DNA fragmentation measured with the neutral comet assay (NCA). Boar semen was diluted in lactose-hen egg yolk-glycerol extender (L-HEY) or lactose ostrich egg yolk lipoprotein fractions-glycerol extender (L-LPFo), packaged into aluminum tubes or plastic straws and frozen in a controlled programmable freezer. In Experiment 1, the chromatin status and DNA fragmentation were measured in fresh and frozen-thawed spermatozoa from the same ejaculates. There was a significant increase in sperm chromatin destabilization and DNA fragmentation in frozen-thawed semen as compared with fresh semen. The proportions of spermatozoa labeled with (3)H-AMD were concurrent with elevated levels of sperm DNA fragmentation in K-3 extender, without cryoprotective substances, compared with L-HEY or L-LPFo extender. Regression analysis revealed that the results of the (3)H-AMD incorporation assay and NCA for frozen-thawed spermatozoa were correlated. Boars differed significantly in terms of post-thaw sperm DNA damage. In Experiment 2, the susceptibility of sperm chromatin to decondensation was assessed using a low concentration of heparin. Treatment of frozen-thawed spermatozoa with heparin revealed enhanced (3)H-AMD binding, suggesting nuclear chromatin decondensation. The deterioration in post-thaw sperm viability, such as motility, mitochondrial function and plasma membrane integrity, was concurrent with increased chromatin instability and DNA fragmentation. This is the first report to show that freezing-thawing procedure facilitated destabilization in the chromatin structure of boar spermatozoa, resulting in

  14. Comparative Metagenomic Analysis Of Microbial Communities From Active Layer And Permafrost After Short-Term Thaw

    Science.gov (United States)

    Vishnivetskaya, T. A.; Chauhan, A.; Saarunya, G.; Murphy, J.; Williams, D.; Layton, A. C.; Pfiffner, S. M.; Stackhouse, B. T.; Sanders, R.; Lau, C. M.; myneni, S.; Phelps, T. J.; Fountain, A. G.; Onstott, T. C.

    2012-12-01

    .Permafrost areas occupy 20-25% of the Earth and extend of 1 km depths. The total number of prokaryotes and their biomass in cold regions are estimated to be 1 x 1030 cells and 140 x1015 g of C, respectively. Thus these environments serve as a reservoir of microbial and biogeochemical activity, which is likely to increase upon thawing. We are currently performing long-term thawing experiments at 4o C on 18, geochemically well-characterized, 1 meter long, intact cores consisting of active-layer (0-70 cm depth) and permafrost, collected from a 7 meter diameter ice-wedge polygon located at the McGill Arctic Research Station on Axel Heiberg Island, Nunavut, Canada. The organic carbon content of these cores averages ~1% at depth but increases to 5.4% in the top 10 cm. The cores were subdivided into four treatment groups: saturated cores (thawed while receiving artificial rain), drained cores (being thawed under natural hydrological conditions), dark cores (thawed under natural hydrological conditions with no light input) and control cores (maintain permafrost table at 70 cm depth). Over the course of 10 weeks the cores were progressively thawed from -4oC to 4oC from the top down to simulate spring thaw conditions in the Arctic. The temperatures at 5 cm, 35 cm, 65 cm, and below the permafrost table in the core were recorded continuously. Pore water and gas samples from 4 depths in each core were collected every two weeks and analyzed for pH, anions, cations, H2, CH4, CO, O2, N2, CO2 and δ13C of CO2. Headspace gas samples were collected weekly and analyzed for the same gases as the pore gases. Sediment sub-samples from the 4 depths were collected and total community genomic DNA (gDNA) was isolated using FastDNA SPIN kit followed by Qiagen column purification. The average yield of gDNA was ~3.5 μg/g of soil for the upper 5 cm active layers and decreased to ~1.5 μg/g of soil in the permafrost. The bacterial 16S copy numbers estimated by real-time quantitative PCR

  15. Consumer Attitudes Toward Storing and Thawing Chicken and Effects of the Common Thawing Practices on Some Quality Characteristics of Frozen Chicken

    OpenAIRE

    Hakan Benli

    2015-01-01

    In this study, a survey was conducted to both evaluate the consumers’ general attitudes for purchasing and storing the raw chicken and determine the thawing practices used for defrosting frozen chicken at home. About 75% of the consumers indicated purchasing chicken meat at least once a week or more. Furthermore, the majority (82.16%) of those who stored at least a portion of the raw chicken stated freezing the raw chicken meat at home. Freezing the chicken meat was considered to have no effe...

  16. Influence of Thawing Methods and Storage Temperatures on Bacterial Diversity, Growth Kinetics, and Biogenic Amine Development in Atlantic Mackerel

    DEFF Research Database (Denmark)

    Onyang, S.; Palmadottir, H.; Tomason, T.

    2016-01-01

    Limited knowledge is currently available on the influence of fish thawing and subsequent storage conditions on bacterial growth kinetics, succession, and diversity alongside the production of biogenic amines. This study aimed to address these factors during the thawing and subsequent storage of m...... amine producing bacteria, with the exception of the genus Proteus, which was 8.6% in fast-thawed mackerel during storage at ambient temperature. This suggests that the decarboxylation potential is dependent on both microbial load and microbial community structure....

  17. Adjusting cryodiluent composition for improved post-thaw quality of rabbit spermatozoa.

    Directory of Open Access Journals (Sweden)

    Sally E Hall

    Full Text Available Improved fertility following artificial insemination with frozen-thawed spermatozoa would offer rabbit producers faster genetic improvement. Previous work investigating cryoprotectants for rabbit spermatozoa have reported inconsistent results. Semen was collected from three rabbit bucks by artificial vagina and frozen using a standard procedure with varied cryodiluent components. Post-thaw analysis encompassed motility, sperm kinematic parameters and acrosome and membrane integrity. Spermatozoa were evaluated at 0, 2 and 4 h after thawing. Experiment 1 compared diluents with 3.5% dimethyl sulfoxide (DMSO, 1.5% acetamide, 1.75% DMSO + 0.75% acetamide or 3.5% DMSO + 1.5% acetamide. The treatment that resulted in the highest post-thaw motility (P<0.001 and acrosome integrity (P<0.001 was DMSO alone. Experiment 2 compared 3.5, 7 and 10% DMSO in the cryodiluent. The best post-thaw sperm motility (P<0.001 and linearity (P = .002 was in 3.5% DMSO, while 10% DMSO afforded higher acrosome/membrane integrity at this last time point (P<0.05. Experiment 3 varied the cryodiluent to contain either 9 or 17% egg yolk or 9 or 17% low density lipoproteins extracted from whole egg yolk. The treatment with the best post-thaw result was 17% egg yolk (motility, P = 0.01; acrosome/membrane integrity, P<0.001. Experiment 4 compared different carbohydrates in the cryodiluent; 50 mM glucose (TCG, 25 mM glucose with 25 mM sucrose (TCGS low, or 50 mM glucose with 50 mM sucrose (TCGS high. When data were pooled across time points, TCG had significantly higher motility than TCGS high (P = 0.021, but was not different from TCGS low. However, TCG had fewer spermatozoa with intact acrosomes and membranes than both TCGS low and TCGS high (P = .002. Put together, these results indicate that the best cryodiluent for rabbit spermatozoa frozen under the conditions used in this paper is with 7% DMSO and 17% egg yolk in a base medium containing 25 mM glucose and 25 mM sucrose.

  18. Freeze-thaw Caenorhabditis elegans freeze-thaw stress response is regulated by the insulin/IGF-1 receptor daf-2.

    Science.gov (United States)

    Hu, Jian-Ping; Xu, Xiao-Ying; Huang, Li-Ying; Wang, Li-shun; Fang, Ning-Yuan

    2015-12-03

    Adaption to cold temperatures, especially those below freezing, is essential for animal survival in cold environments. Freezing is also used for many medical, scientific, and industrial purposes. Natural freezing survival in animals has been extensively studied. However, the underlying mechanisms remain unclear. Previous studies demonstrated that animals survive in extremely cold weather by avoiding freezing or controlling the rate of ice-crystal formation in their bodies, which indicates that freezing survival is a passive thermodynamic process. Here, we showed that genetic programming actively promotes freezing survival in Caenorhabditis elegans. We found that daf-2, an insulin/IGF-1 receptor homologue, and loss-of-function enhanced survival during freeze-thaw stress, which required the transcription factor daf-16/FOXO and age-independent target genes. In particular, the freeze-thaw resistance of daf-2(rf) is highly allele-specific and has no correlation with lifespan, dauer formation, or hypoxia stress resistance. Our results reveal a new function for daf-2 signaling, and, most importantly, demonstrate that genetic programming contributes to freezing survival.

  19. Durability of cracked fibre reinforced concrete exposed to freeze-thaw and deicing salt

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan De Place

    1998-01-01

    -thaw and deicing salt. The concrete has a water-powder ratio of 0.38 including both fly ash and silica fume. Both steel fibres (ZP, 0.4 vol%) and polypropylene fibres (PP, 1 vol%) are used as well as main reinforcement. The freeze-thaw test emphasizes the need for a critical evaluation of the mix design and mixing...... methods when designing FRC-structures. The scaling is increased by a factor 5 to 10 when adding fibres to the concrete while the air content is below 4% by volume. The variation of the scaling increases when adding fibres. Capillary water uptake in uncracked specimens of FRC was 20-30% higher at 1°C than...... at 20°C for both ZP- and PP-fibres, while the temperature had no effect on the water uptake in plain concrete.(This abstract is a short version of the published abstract)...

  20. Thaw Depth Determines Dissolved Organic Carbon Concentration and Biodegradability on the Northern Qinghai-Tibetan Plateau

    Science.gov (United States)

    Mu, C. C.; Abbott, B. W.; Wu, X. D.; Zhao, Q.; Wang, H. J.; Su, H.; Wang, S. F.; Gao, T. G.; Guo, H.; Peng, X. Q.; Zhang, T. J.

    2017-09-01

    The response of dissolved organic carbon (DOC) flux to permafrost degradation is one of the major sources of uncertainty in predicting the permafrost carbon feedback. We investigated DOC export and properties over two complete flow seasons in a catchment on the northern Qinghai-Tibetan Plateau. DOC concentration and biodegradability decreased systematically as thaw depth increased through the season, attributable to changing carbon sources and degree of microbial processing. Increasing DOC aromaticity and δ13C-DOC indicated shifts toward more recalcitrant carbon sources and greater residence time in soils prior to reaching the stream network. These strong and consistent seasonal trends suggest that gradual active layer deepening may decrease DOC export and biodegradability from permafrost catchments. Because these patterns are opposite observations from areas experiencing abrupt permafrost collapse (thermokarst), the overall impact of permafrost degradation on DOC flux and biodegradability may depend on the proportion of the landscape experiencing gradual thaw versus thermokarst.

  1. Dimensional and ice content changes of hardened concrete at different freezing and thawing temperatures

    DEFF Research Database (Denmark)

    Johannesson, Björn

    2010-01-01

    and the corresponding measured length changes. The development of cracks in the material structure was indicated by an ultra-sonic technique by measuring on the samples before and after the freeze-thaw tests. Further the air void structure was investigated using a microscopic technique in which air'bubble' size...... distributions and the so-called spacing factor, indicating the mean distance between air bubbles, were measured. By analyzing the experimental result, it is concluded that damages occur in the temperature range of about -10 degrees C to -55 degrees C, when the air content is lower than about 4% of the total...... temperatures can be calculated. The length change caused by temperature and ice content changes during test is measured by a separate experiment using the same types of freeze-thaw cycles as in the calorimetric tests. In this way it was possible to compare the amount of formed ice at different temperatures...

  2. Electron acceptor-based regulation of microbial greenhouse gas production from thawing permafrost

    DEFF Research Database (Denmark)

    Bak, Ebbe Norskov; Jones, Eleanor; Yde, Jacob Clement

    of sulfate and iron and the microbial community structure regulate the production of CO2 and CH4 in thawing permafrost, and to elucidate how the rate of the organic carbon degradation changes with depth in permafrost-affected soils. This study improves our understanding of climate feedback mechanisms......Permafrost contains about 35% of the global soil organic carbon (0-3 m depth). As a consequence of global warming, the active layer thickness is steadily increasing and its organic carbon is becoming available for degradation, causing a concomitant release of CO2 and CH4. The climate forcing...... feedbacks of permafrost thaw are determined by the rate of organic carbon degradation and to which degree it is released as CO2 or CH4. Methane is produced under anoxic conditions, but the factors that regulate its production are poorly constrained. In this study, we investigate how CH4 production...

  3. Ultrastructure of spores of Rhizopus nigricans after repeated freezing and thawing shocks.

    Science.gov (United States)

    Necas, O; Gabriel, M

    1980-01-01

    Disintegration of nuclear envelopes is the only ultrastructural change detectable by freeze-etching in dormant spores of the mould Rhizopus nigricans, both dry and swollen, subjected to repeated freezing and thawing. The increase of the number of freeze-inactivated spores corresponds well with the increase of the number of damaged nuclei. This fact led us to formulate a hypothesis that the structure of the nucleus is the primary target of the freezing or thawing damage. As other biomembranes are not damaged it may be assumed that the disintegration of the nuclear membrane is probably secondary. No changes in ultrastructure of metabolically activated spores could be detected, in spite of the fact that the spores lost their germinative ability. Thus, the mechanism of the freeze injury may be different in dormant and growing spores.

  4. The Effect of Freeze - thaw Cycles on Slope Anchorage and Preventive Measures of Research

    Science.gov (United States)

    Bi, Quanchao; Wang, Xuelei; Zhang, Mingxiu; Rao, Qiang; Fu, Zhixin; Su, Jianyao

    2017-10-01

    Freeze-thaw cycles have great harm to slope anchorage structure, and the theoretical system has not been formed because there are too many constraints and interrelations. This paper analyzes the failure principle and appearance of the slope under the freeze-thaw cycles and puts forward the prevention and control measures. On the whole, at this stage there is no way to raise the anchoring technology as a system to do the whole study. It is urgent to establish a complete concept and overall evaluation mechanism of rock and soil anchoring system, because it can give full play to the function of the favorable elements in the anchoring system and weaken the harm of the unfavorable elements so that the system can achieve the best working condition.

  5. Effects of freeze-thaw cycles on microarthropods and nutrient availability in a sub-arctic soil

    DEFF Research Database (Denmark)

    Sjursen, Heidi; Michelsen, Anders; Holmstrup, Martin

    2005-01-01

    content were examined. There was no conclusive evidence that recurring freeze-thaw events had a negative effect on the investigated soil faunal groups, and the treatment even seemed to stimulate the abundance of Acaridida. Respiration of soil subjected to 16 freeze-thaw cycles was low when kept at -2 °C......It is predicted that Arctic regions may experience an increase in mean temperature in the future. This will affect the frequency of severe climatic events such as summer droughts and freeze-thaw cycles. In order to understand the impact of recurring freezing and thawing on soil organisms...... and their environment, intact plant-soil samples from the sub-Arctic were subjected to a series of such events. Springtail and mite species composition and abundance were monitored at intervals throughout the experiment. Furthermore, nutrient content and mobilisation in the soil and soil microbial biomass and nutrient...

  6. Effects of Technological Parameters and Fishing Ground on Quality Attributes of Thawed, Chilled Cod Fillets Stored in Modified Atmosphere Packaging

    DEFF Research Database (Denmark)

    Bøknæs, Niels; Østerberg, Carsten; Sørensen, Rie

    2001-01-01

    frozen storage is more appropriate for manufacturing of thawed chilled MAP cod fillets. During chill storage of thawed MAP Barents Sea fillets previously kept at -30degreesC for 15 weeks, significant growth of Photobacterium phosphoreum and production of trimethylamine were observed. Oil the contrary, P....... phosphoreum growth and trimethylamine production in thawed and chill-stored MAP Baltic Sea cod fillets were strongly inhibited after as little as 4 weeks of frozen storage at -30degreesC. Contents of trimethylamine oxide and NaCl were substantially higher in fillets of Barents Sea cod compared to fillets...... of Baltic Sea cod. Therefore, addition of trimethylamine oxide and NaCl to Baltic Sea cod fillets was evaluated and shown to protect P, phosphoreum against fro::en storage inactivation and this explained the observed differences in growth of the spoilage bacteria and trimethylamine production between thawed...

  7. Pre-ABoVE: Vegetation, NDVI, Snow and Thaw Depths, in North Slope, Alaska and NWT, CA

    Data.gov (United States)

    National Aeronautics and Space Administration — This dataset includes vegetation cover maps, Normalized Difference Vegetation Index (NDVI) maps, snow depth and thaw depth data that were obtained as part of a...

  8. Changes in Catchment-Scale Recession Flow Properties in Response to Permafrost Thawing in the Yukon River Basin

    National Research Council Canada - National Science Library

    Lyon, Steve W; Destouni, Georgia

    2010-01-01

    ...), covering large portions of Alaska, USA and parts of Canada. The changes in the recession flow properties detected in the YRB agree well with observations of permafrost thawing across central Alaska...

  9. Modification of ASTM C666 for testing resistance of concrete to freezing and thawing in sodium chloride solution.

    Science.gov (United States)

    1978-01-01

    Since 1961 the Research Council has used equipment manufactured by Conrad, Inc. for exposing concrete specimens to rapid cycles of freezing and thawing. In addition, the Materials Division of the Virginia Department of Highways and Transportation sen...

  10. Freezing and thawing of processed meat in an industrial freezing tunnel

    OpenAIRE

    Glaucio Antonio Marini; Eduarda Molardi Bainy; Marcelo Kaminski Lenzi; Marcos Lúcio Corazza

    2014-01-01

    Freezing is a commonly used preservation method in the meat industry. The understanding of the product behavior during the freezing process can assist in a better process management and quality control. This work reports the study of freezing and thawing of three types of processed meat in order to determine process parameters in an industrial forced‑air freezing tunnel at ‑30oC. Chicken sausages (frankfurter type), mortadela (bologna type) and mechanically deboned chicken meat (MDCM) were st...

  11. Effect of conventional and controlled freezing method on the post thaw characteristics of boar spermatozoa.

    Science.gov (United States)

    Baishya, S K; Biswas, R K; Kadirvel, G; Deka, B C; Kumar, Suresh; Sinha, S; Dutta, D J; Saikia, G K

    2014-10-01

    The objective of the present study was to evaluate the effectiveness of conventional, and controlled freezing method adopting three freezing rates 20°C, 40°C and 60°C/min for cryopreservation of boar semen. Sixty sperm-rich fractions of ejaculates from six boars were utilized for freezing of semen with different freezing methods in lactose-egg yolk glycerol extender using 0.5 ml straws. Semen samples were evaluated for sperm motility, live sperm, acrosome integrity, plasma membrane integrity (PMI) by carboxyfluorescein diacetate plus propidium iodide (PI) staining, mitochondrial membrane potential (MMP) by combined JC-1 plus PI staining and lipid peroxidation (LPO) by BODIPY (581/591)-C11 probe after equilibration and after freezing. The results revealed that the post thaw sperm motility, live sperm, live intact acrosome and plasma membrane integrity were significantly (pfreezing methods (20°C, 40°C and 60°C/min) as compared to that in conventional method. In addition, the controlled freezing methods yielded higher (p>0.05) mean values of live sperm with high MMP as compared to conventional freezing. However, the post thaw sperm LPO did not influence by difference in freezing methods. No significant difference on the post thaw sperm qualities was recorded among the three controlled freezing rates. All the sperm parameters assessed declined significantly (pfreezing as compared to that after equilibration irrespective of freezing method employed. In conclusion, cryopreservation of boar semen with controlled freezing methods conferred better post thaw sperm quality as compared to conventional method, and the freezing rates of either 20, 40 or 60°C/min could provide better freezability of boar semen. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Comparative stability of canine and feline hemostatic proteins in freeze-thaw-cycled fresh frozen plasma.

    Science.gov (United States)

    Yaxley, Page E; Beal, Matthew W; Jutkowitz, L Ari; Hauptman, Joe G; Brooks, Marjory B; Hale, Anne S; Parr, Alice

    2010-10-01

    To evaluate the stability of canine and feline hemostatic proteins in freeze-thaw-cycled (FTC) fresh frozen plasma (FFP). Prospective study. Veterinary Teaching Hospital. Nine blood donor dogs and 10 blood donor cats. Whole blood was collected and separated into packed RBC and plasma units according to standard methods. Each unit of plasma was divided into 2 equal aliquots and frozen (-41 °C). One aliquot from each donor (FTC) was then thawed and then refrozen (-41 °C) until time of analysis. The second aliquot (nonfreeze-thaw-cycled; NFTC) remained frozen until time of analysis. The hemostatic proteins assessed included coagulation factors, anticoagulant factors (antithrombin and Protein C), and adhesive proteins (fibrinogen and von Willebrand Factor). The coagulant activities of factors II, VII, VIII, IX, X, XI, and XII were measured in modified one-stage activated partial thromboplastin time or prothrombin time assays. Antithrombin and Protein C activities were measured in chromogenic substrate assays. Clottable fibrinogen was measured via the Clauss method, and von Willebrand Factor concentration (vWF:Ag) was measured in an ELISA. A paired t-test was utilized to identify differences in factor activity or concentration between FTC FFP and NFTC FFP. No clinically or statistically significant differences (all P>0.05) were identified between FTC FFP and NFTC FFP. Refreezing FFP within 1 hour of initial thawing appeared to have no deleterious effects on the hemostatic protein activity or content of that unit. Transfusion of FTC FFP is expected to provide the recipient with comparable replacement of hemostatic proteins as FFP that has remained frozen. © Veterinary Emergency and Critical Care Society 2010.

  13. Effect of alpha-lipoic acid on boar spermatozoa quality during freezing-thawing

    Science.gov (United States)

    Alpha-lipoic acid (ALA) is known as a natural antioxidant. The aim of the present study was to evaluate the cryoprotective effect of ALA on the motility of boar sperm and the antioxidant effect of ALA on boar sperm during freezing-thawing. Different concentrations (2.0, 4.0, 6.0, 8.0, and 10.0, mg/m...

  14. Nutrient Controls on Methane Emissions in a Permafrost Thaw Subarctic Peatland

    Science.gov (United States)

    Kashi, N. N.; Perryman, C. R.; Malhotra, A.; Marek, E. A.; Giesler, R.; Varner, R. K.

    2015-12-01

    Permafrost peatlands in northern latitudes are large reservoirs of sequestered carbon that are vulnerable to climate change. While peatlands account for a small fraction of total global land surfaces, their potential to release sequestered carbon in response to higher temperatures is of concern. Of particular relevance is the conversion of these carbon stores into methane (CH4), a strong greenhouse gas with a global warming potential 20 times greater than that of CO2 over a 100-year time frame. Here, we explore how key nutrients impact the consumption of CH4 at the Stordalen Mire in Abisko, Sweden, a discontinuous permafrost peatland with expanding thaw over the last century. Peatland CH4 emissions are highly spatially variable due to multiple emission pathways and strong dependence on several environmental factors. Among controls on CH4 emissions, such as temperature and water table depth, primary production of wetland vegetation is also a strong factor in the variability of CH4 emissions. Plant community shifts among permafrost thaw stages subsequently change nutrient cycling and availability, which in turn impacts primary production. Early stages of permafrost thaw are mosaicked with a variety of vascular plants and mosses. We analyzed potential enzymatic activities of chitinase, glucosidase, and phosphatase as proxies for organic nitrogen, carbon, and phosphorus cycling, respectively, in tandem with potential CH4 oxidation rates. In addition, stoichiometric ratios of carbon, nitrogen, and phosphorus concentrations are used to illustrate nutrient limitation controls on CH4 oxidation rates. While CH4 emissions are low throughout initial thaw stages, plant communities and the methanotrophic microbes they harbor.

  15. Comparison of neonatal outcomes following progesterone use during ovarian stimulation with frozen-thawed embryo transfer

    OpenAIRE

    Zhu, Xiuxian; Ye, Hongjuan; Fu, Yonglun

    2017-01-01

    Progesterone soft capsules (brand name: Utrogestan) were demonstrated to be an effective oral alternative to prevent premature LH surges both in normal-ovulatory and polycystic ovarian syndrome (PCOS) patients. However, its safety in terms of neonatal outcomes is unclear. To evaluate whether Utrogestan use increase the risk of adverse neonatal outcomes compared with short protocol in patients undergoing IVF/ICSI treatments in combination with frozen-thawed embryo transfer (FET), we performed ...

  16. NifH- Harboring Bacterial Community Composition Across an Alaskan Permafrost Thaw Gradient

    Directory of Open Access Journals (Sweden)

    Christopher Ryan Penton

    2016-11-01

    Full Text Available Since nitrogen (N is often limiting in permafrost soils, we investigated the N2-fixing genetic potential and the inferred taxa harboring those genes by sequencing nifH gene fragments in samples taken along a permafrost thaw gradient in an Alaskan boreal soil. Samples from minimally, moderately and extensively thawed sites were taken to a depth of 79 cm to encompass zones above and below the depth of the water table. NifH reads were translated with frameshift correction and 112,476 sequences were clustered at 5% amino acid dissimilarity resulting in 1,631 OTUs. Sample depth in relation to water table depth was correlated to differences in the NifH sequence classes. NifH sequences most closely related to group I nifH-harboring Alpha- and Beta Proteobacteria were in higher abundance above water table depth while those related to group III nifH-harboring Delta and Gamma Proteobacteria were more abundant below. The most dominant below water table depth NifH sequences, comprising 1/3 of the total, were distantly related to Verrucomicrobia-Opitutaceae. Overall, these results suggest that permafrost thaw alters the class-level composition of N2-fixing communities in the thawed soil layers and that this distinction corresponds to the depth of the water table. These nifH data were also compared to nifH sequences obtained from a study at an Alaskan taiga site, and to those of other geographically distant, non-permafrost sites. The two Alaska sites were differentiated largely by changes in relative abundances of the same OTUs, whereas the non-Alaska sites were differentiated by the lack of many Alaskan OTUs, and the presence of unique halophilic, sulfate- and iron-reducing taxa in the Alaska sites.

  17. Monitoring rock freezing and thawing by novel geoelectrical and acoustic techniques

    OpenAIRE

    Murton, Julian B.; Kuras, Oliver; Krautblatter, Michael; Cane, Tim; Tschofen, Dominique; Uhlemann, Sebastian; Schober, Sandra; Watson, Phil

    2016-01-01

    Automated monitoring of freeze-thaw cycles and fracture propagation in mountain rockwalls is 23 needed to provide early warning about rockfall hazards. Conventional geoelectrical methods 24 such as electrical resistivity tomography (ERT) are limited by large and variable ohmic contact 25 resistances, requiring galvanic coupling with metal electrodes inserted into holes drilled into 26 rock, and which can be loosened by rock weathering. We report a novel experimental 27 methodology that combin...

  18. Sensitivity of airborne geophysical data to sublacustrine and near-surface permafrost thaw

    Science.gov (United States)

    Minsley, Burke J.; Wellman, Tristan; Walvoord, Michelle Ann; Revil, Andre

    2014-01-01

    A coupled hydrogeophysical forward and inverse modeling approach is developed to illustrate the ability of frequency-domain airborne electromagnetic (AEM) data to characterize subsurface physical properties associated with sublacustrine permafrost thaw during lake-talik formation. Numerical modeling scenarios are evaluated that consider non-isothermal hydrologic responses to variable forcing from different lake depths and for different hydrologic gradients. A novel physical property relationship connects the dynamic distribution of electrical resistivity to ice saturation and temperature outputs from the SUTRA groundwater simulator with freeze–thaw physics. The influence of lithology on electrical resistivity is controlled by a surface conduction term in the physical property relationship. Resistivity models, which reflect changes in subsurface conditions, are used as inputs to simulate AEM data in order to explore the sensitivity of geophysical observations to permafrost thaw. Simulations of sublacustrine talik formation over a 1000-year period are modeled after conditions found in the Yukon Flats, Alaska. Synthetic AEM data are analyzed with a Bayesian Markov chain Monte Carlo algorithm that quantifies geophysical parameter uncertainty and resolution. Major lithological and permafrost features are well resolved by AEM data in the examples considered. The subtle geometry of partial ice saturation beneath lakes during talik formation cannot be resolved using AEM data, but the gross characteristics of sub-lake resistivity models reflect bulk changes in ice content and can identify the presence of a talik. A final synthetic example compares AEM and ground-based electromagnetic responses for their ability to resolve shallow permafrost and thaw features in the upper 1–2 m below ground outside the lake margin.

  19. The transcriptional response of microbial communities in thawing Alaskan permafrost soils

    OpenAIRE

    Coolen, M.J.L.; Orsi, William D.

    2015-01-01

    Thawing of permafrost soils is expected to stimulate microbial decomposition and respiration of sequestered carbon. This could, in turn, increase atmospheric concentrations of greenhouse gases, such as carbon dioxide and methane, and create a positive feedback to climate warming. Recent metagenomic studies suggest that permafrost has a large metabolic potential for carbon processing, including pathways for fermentation and methanogenesis. Here, we performed a pilot study using ultrahigh throu...

  20. The transcriptional response of microbial communities in thawing Alaskan permafrost soils

    OpenAIRE

    Coolen, Marco J. L.; Orsi, William D.

    2015-01-01

    Thawing of permafrost soils is expected to stimulate microbial decomposition and respiration of sequestered carbon. This could, in turn, increase atmospheric concentrations of greenhouse gasses, such as carbon dioxide and methane, and create a positive feedback to climate warming. Recent metagenomic studies suggest that permafrost has a large metabolic potential for carbon processing, including pathways for fermentation and methanogenesis. Here, we performed a pilot study using ultrahigh thro...

  1. Viability of Frozen-Thawed Epididymal Sperm of Garut Ram Cryopreserved with Modified Tris Extender

    Directory of Open Access Journals (Sweden)

    MUHAMMAD RIZAL

    2005-06-01

    Full Text Available Sperm collected from cauda epididymis is a source of male gametes. The purposes of this study was to evaluate an quality of frozen-thawed sperm of garut ram which was collected from cauda epididymis and cryopreserved with modified Tris extender, i.e: Tris extender (control, KT, Tris extender + 60 mM lactose (LS, and Tris extender + 60 mM lactose + 0.05% glutathione (GL. Quality of collected sperm including concentration, motility, live sperm, abnormality, cytoplasmic droplet, intact acrosomal cap (IAC, and intact plasma membrane (IPM were evaluated. Results showed that mean of sperm concentration, percentages of motility, live sperm, abnormality, cytoplasmic droplet, IAC, and IPM of fresh epididymal sperm were 13,993.33 million/ml, 70.83, 82.83, 10.83, 8.5, 85.83, and 81.33%, respectively. Sperm quality after equilibration for LS and GL were significantly (P<0.05 higher than KT. Mean percentages of post thawing sperm motility, live sperm, IAC, and IPM for GL (45, 54.5, 47.83, and 48.83% were significantly (P<0.05 higher than LS (40, 49.17, 43.83, and 44.5%, and KT (35, 42.5, 39.17, and 41.5%. Mean percentages of post thawing sperm motility, live sperm, IAC, and IPM for LS were significantly (P<0.05 higher than those of KT. Hence, frozen-thawed epididymal sperm of garut ram after slaughter and cryopreserved with Tris extender + 60 mM lactose (LS and Tris extender + 60 mM lactose + 0.05% glutathione (GL possibly can be used for artificial insemination (AI or in vitro embryo production program.

  2. Influence of platelet lysate on the recovery and metabolic performance of cryopreserved human hepatocytes upon thawing.

    Science.gov (United States)

    Tolosa, Laia; Bonora-Centelles, Ana; Donato, M Teresa; Mirabet, Vicente; Pareja, Eugenia; Negro, Alejandro; López, Silvia; Castell, José V; Gómez-Lechón, M José

    2011-06-27

    Storage of human hepatocytes is essential for their use in research and liver cell transplantation. However, cryopreservation and thawing (C/T) procedures have detrimental effects on the viability and functionality compared with fresh cells. The aim of this study was to upgrade the standard C/T methodology to obtain better quality hepatocytes for cell transplantation to improve the overall clinical outcome. Human hepatocytes isolated from donor livers were cryopreserved in University of Wisconsin solution with 10% dimethyl sulfoxide (standard medium), which was supplemented with 10% or 20% of platelet lysate. Thawing media supplemented with up to 30 mM glucose was also investigated. The effects on cell viability, adhesion proteins (e-cadherin, β-catenin, and β1-integrin) expression, attachment efficiency, apoptotic indicators, Akt signaling, ATP levels, and cytochrome P450 activities have been evaluated. The results indicate that the hepatocytes cryopreserved in a medium supplemented with platelet lysate show better recovery than those preserved in the standard medium: higher expression of adhesion molecules, higher attachment efficiency and cell survival; decreased number of apoptotic nuclei and caspase-3 activation; maintenance of ATP levels; and drug biotransformation capability close to those in fresh hepatocytes. Supplementation of thawing media with glucose led to a significant decrease in caspase-3 activation and to increased adhesion molecules preservation and Akt signal transduction after C/T. Minor nonsignificant changes in cell viability and attachment efficiency were observed. These promising results could lead to a new cryopreservation procedure to improve human hepatocyte cryopreservation outcome.

  3. THE INFLUENCE OF SLOW THAWING ON EVOLUTION OF SOME BIOCHEMICAL COMPOUNDS IN FROZEN FISHES

    Directory of Open Access Journals (Sweden)

    Marcel AVRAMIUC

    2017-06-01

    Full Text Available The aim of this work was to study the evolution of pH, amino nitrogen and nitrogen from aminoacids in four fish species, during 48 hours of slow thawing, in order to assess the fish spoilage speed in these keeping conditions. The biological material was represented by frozen fishes (carp, catfish, mackerel and hake which were subjected to slow thawing at room temperature (+20..+22°C, by analysing, at certain time intervals, pH, amino nitrogen - AN (mg %, and nitrogen from aminoacids - NAA (g %. The pH was determined with a digital pH-meter type Hanna, and the nitrogen from aminoacids according to Sörensen method. The amino nitrogen was determined by the difference between the nitrogen content of volatile bases and the nitrogen content of the ammonia and primary amines. As compared to frozen samples, both pH and the amino nitrogen values of all fish samples showed constant and significant increases up to the end of the analyzed period, while the nitrogen from aminoacids only in the first 30 hours of thawing. The amino nitrogen and the nitrogen from amino acids values have indicated the highest spoilage speed in catfish and hake, and the least speed in mackerel.

  4. Improvement of cloning efficiency in minipigs using post-thawed donor cells treated with roscovitine.

    Science.gov (United States)

    Hwang, Seongsoo; Oh, Keon Bong; Kwon, Dae-Jin; Ock, Sun-A; Lee, Jeong-Woong; Im, Gi-Sun; Lee, Sung-Soo; Lee, Kichoon; Park, Jin-Ki

    2013-11-01

    Massachusetts General Hospital miniature pigs (MGH minipigs) have been established for organ transplantation studies across the homozygous major histocompatibility complex, but cloning efficiency of MGH minipigs is extremely low. This study was designed to increase the productivity of MGH minipigs by nuclear transfer of post-thaw donor cells after 1 h co-incubation with roscovitine. The MGH minipig cells were genetically modified with GT KO (alpha1,3-galactosyltransferase knock-out) and hCD46 KI (human CD46 knock-in) and used as donor cells. The GT KO/hCD46 KI donor cells were cultured for either 3 days (control group) or 1 h after thawing with 15 μM roscovitine (experimental group) prior to the nuclear transfer. The relative percentage of the transgenic donor cells that entered into G0/G1 was 93.7 % (±2.54). This was different from the donor cells cultured for 1 h with the roscovitine-treated group (84.6 % ±4.6) (P cloning efficiency ranged from 0.74 to 2.54 %. In conclusion, gene-modified donor cells can be used for cloning of MGH minipigs if the cells are post-thawed and treated with roscovitine for 1 h prior to nuclear transfer.

  5. Oil recovery from refinery oily sludge via ultrasound and freeze/thaw.

    Science.gov (United States)

    Zhang, Ju; Li, Jianbing; Thring, Ronald W; Hu, Xuan; Song, Xinyuan

    2012-02-15

    The effective disposal of oily sludge generated from the petroleum industry has received increasing concerns, and oil recovery from such waste was considered as one feasible option. In this study, three different approaches for oil recovery were investigated, including ultrasonic treatment alone, freeze/thaw alone and combined ultrasonic and freeze/thaw treatment. The results revealed that the combined process could achieve satisfactory performance by considering the oil recovery rate and the total petroleum hydrocarbon (TPH) concentrations in the recovered oil and wastewater. The individual impacts of five different factors on the combined process were further examined, including ultrasonic power, ultrasonic treatment duration, sludge/water ratio in the slurry, as well as bio-surfactant (rhamnolipids) and salt (NaCl) concentrations. An oil recovery rate of up to 80.0% was observed with an ultrasonic power of 66 W and an ultrasonic treatment duration of 10 min when the sludge/water ratio was 1:2 without the addition of bio-surfactant and salt. The examination of individual factors revealed that the addition of low concentration of rhamnolipids (oil recovery from the combined treatment process. The experimental results also indicated that ultrasound and freeze/thaw could promote the efficiency of each other, and the main mechanism of oil recovery enhancement using ultrasound was through enhanced desorption of petroleum hydrocarbons (PHCs) from solid particles. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. EFFECT OF DIFFERENT MODES OF THAWING ON CRYOPRESERVED SPERM MOTILITY GRASS CARP (CTENOPHARYNGODON IDELLA

    Directory of Open Access Journals (Sweden)

    D. Syrovatka

    2013-03-01

    Full Text Available Implementation of deep freeze genital products (cryopreservation in fish practice the need of continuation of optimizing process of defrosting parameters. The important defines element is the proper matching of the temperature water bath and exposing inside. This research was carried out for the purpose of investigation investigate the effect of different thawing procedures for motility and fertilizing capacity of frozen/thawed grass carp (Ctenopharyngodon idella sperm. The studies were conducted during the spawning company in 2012 at the experimental farm "Nyvka" and Institute Fisheries NAAS. The optimal mode of defrostation was conducted among nine variants of the experiment. The conditions of each experiments are determined combination of three temperature water baths: 30, 35 and 40°C and the corresponding exposures of the holding inside it with frozen sperm microtubules of grass carp: 10, 20 and 30 seconds.The best result for parameters such as total time of motion and percentage of live sperm during thawing and activated sperm were obtained at 35°C and 30 seconds of exposure. Number of live spermatozoa’s reached 77,4±0,57% and time of their movement 75±2,0 seconds. Eggs after ovulation were fertilized by received sperm for the purpose of checking of semen fertilizing capacity. Artificial fertilization was 85,6±2,8% that to confirm fertility received sperm.

  7. Basic study on promotion of thawing frozen soil by shock loading

    Directory of Open Access Journals (Sweden)

    Toshiaki WATANABE

    2008-06-01

    Full Text Available The aim of study is to confirm a new technique that can crush the frozen soil and/or ice block using underwater shock wave generated by the underwater explosion of explosive. This technique can lead to the earlier sowing, which can have the larger harvest because the duration of sunshine increases. Especially, in Hokkaido prefecture, Japan, if the sowing is carried out in April, we can expect to have 150% of harvest in the ordinary season. In the case of small processing area such as road repairing, frozen soil is thawed by using the heat of gas burner and/or the electric heater. It is not a suitable plan to apply these heating methods to agriculture, from the point of view enormous amount of processing area. Thawing technique for frozen soil is effective against the cold regions, for example, Russia, Norway, and Sweden, etc. At first, we carried out experiments using a detonating fuse and ice block. The propagation process of shock wave into the ice block was observed by means of a high-speed camera. In order to check about that influence we tried to give an actual frozen soil a shock wave. We could get a result that existence of water layer serves an important role in promotion of thawing by the shock loading to the frozen soil.

  8. Dissolved organic carbon loss from Yedoma permafrost amplified by ice wedge thaw

    Science.gov (United States)

    Vonk, J. E.; Mann, P. J.; Dowdy, K. L.; Davydova, A.; Davydov, S. P.; Zimov, N.; Spencer, R. G. M.; Bulygina, E. B.; Eglinton, T. I.; Holmes, R. M.

    2013-09-01

    Pleistocene Yedoma permafrost contains nearly a third of all organic matter (OM) stored in circum-arctic permafrost and is characterized by the presence of massive ice wedges. Due to its rapid formation by sediment accumulation and subsequent frozen storage, Yedoma OM is relatively well preserved and highly biologically available (biolabile) upon thaw. A better understanding of the processes regulating Yedoma degradation is important to improve estimates of the response and magnitude of permafrost carbon feedbacks to climate warming. In this study, we examine the composition of ice wedges and the influence of ice wedge thaw on the biolability of Yedoma OM. Incubation assays were used to assess OM biolability, fluorescence spectroscopy to characterize the OM composition, and potential enzyme activity rates to examine the controls and regulation of OM degradation. We show that increasing amounts of ice wedge melt water in Yedoma-leached incubations enhanced the loss of dissolved OM over time. This may be attributed to the presence of low-molecular weight compounds and low initial phenolic content in the OM of ice wedges, providing a readily available substrate that promotes the degradation of Yedoma OC. The physical vulnerability of ice wedges upon thaw (causing irreversible collapse), combined with the composition of ice wedge-engrained OM (co-metabolizing old OM), underlines the particularly strong potential of Yedoma to generate a positive feedback to climate warming relative to other forms of non-ice wedge permafrost.

  9. Collaborative Research. Quantifying Climate Feedbacks of the Terrestrial Biosphere under Thawing Permafrost Conditions in the Arctic

    Energy Technology Data Exchange (ETDEWEB)

    Zhuang, Qianlai [Purdue Univ., West Lafayette, IN (United States); Schlosser, Courtney [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Melillo, Jerry [Marine Biological Lab. (MBL), Woods Hole, MA (United States); Walter, Katey [Univ. of Alaska, Fairbanks, AK (United States)

    2015-09-15

    Our overall goal is to quantify the potential for threshold changes in natural emission rates of trace gases, particularly methane and carbon dioxide, from pan-arctic terrestrial systems under the spectrum of anthropogenically-forced climate warming, and the conditions under which these emissions provide a strong feedback mechanism to global climate warming. This goal is motivated under the premise that polar amplification of global climate warming will induce widespread thaw and degradation of the permafrost, and would thus cause substantial changes to the landscape of wetlands and lakes, especially thermokarst (thaw) lakes, across the Arctic. Through a suite of numerical experiments that encapsulate the fundamental processes governing methane emissions and carbon exchanges – as well as their coupling to the global climate system - we intend to test the following hypothesis in the proposed research: There exists a climate warming threshold beyond which permafrost degradation becomes widespread and stimulates large increases in methane emissions (via thermokarst lakes and poorly-drained wetland areas upon thawing permafrost along with microbial metabolic responses to higher temperatures) and increases in carbon dioxide emissions from well-drained areas. Besides changes in biogeochemistry, this threshold will also influence global energy dynamics through effects on surface albedo, evapotranspiration and water vapor. These changes would outweigh any increased uptake of carbon (e.g. from peatlands and higher plant photosynthesis) and would result in a strong, positive feedback to global climate warming.

  10. An unusual MR signal reduction artefact in an incompletely thawed cadaver spine specimen

    Energy Technology Data Exchange (ETDEWEB)

    Kurmis, Andrew P. [Bone and Joint Research Laboratory, Division of Tissue Pathology, Institute of Medical and Veterinary Science and Hanson Institute, South Australia (Australia); School of Medicine, Flinders University, South Australia (Australia)], E-mail: andrew.kurmis@flinders.edu.au; Slavotinek, John P. [Department of Medical Imaging, Flinders Medical Centre, South Australia (Australia); Barber, Christine; Smith, Lachlan [Bone and Joint Research Laboratory, Division of Tissue Pathology, Institute of Medical and Veterinary Science and Hanson Institute, South Australia (Australia); Fazzalari, Nicola L. [Bone and Joint Research Laboratory, Division of Tissue Pathology, Institute of Medical and Veterinary Science and Hanson Institute, South Australia (Australia); Department of Pathology, University of Adelaide, South Australia (Australia)

    2009-02-15

    Objective: Within the contemporary constraints associated with in vivo use for research purposes, preservation of macroscopic human tissue specimens is of critical importance. Simple sub-zero freezing remains the method-of-choice for medium-term storage of such material. Despite widespread use, few papers have described the effects of this preservation method on resultant images, or the impact of inadequate tissue thawing. Materials and methods: A series of post-mortem-harvested human lumbar spine specimens were undergoing conventional MR imaging as part of a larger project exploring non-invasive hydration status assessment of the intervertebral disc. Results: A complex central signal reduction artefact was noted during scanning of one specimen, resembling an isotherm distribution. Subtle inadequacies in core specimen thawing lead to an initially confusing pattern of central signal dampening. Conclusions: These findings demonstrate the impact of sub-optimal specimen preparation on image signal characteristics and highlight the importance of appropriate thawing methods of frozen tissue specimens prior to imaging.

  11. Long-term anoxia and release of ancient, labile carbon upon thaw of Pleistocene permafrost

    Science.gov (United States)

    Ewing, Stephanie A.; O'Donnell, Jonathan A.; Aiken, George R.; Butler, Kenna; Butman, David; Windham-Myers, Lisamarie; Kanevskiy, Mikhail

    2015-01-01

    The fate of permafrost carbon upon thaw will drive feedbacks to climate warming. Here we consider the character and context of dissolved organic carbon (DOC) in yedoma permafrost cores from up to 20 m depth in central Alaska. We observed high DOC concentrations (4 to 129 mM) and consistent low molecular weight organic acid concentrations in three cores. We estimate a DOC production rate of 12 µmol DOC m−2 yr−1 based on model ages of up to ~200 kyr derived from uranium isotopes. Acetate C accounted for 24 ± 1% of DOC in all samples. This proportion suggests long-term anaerobiosis and is likely to influence thaw outcomes due to biolability of acetate upon release in many environments. The combination of uranium isotopes, ammonium concentrations, and calcium concentrations explained 86% of the variation in thaw water DOC concentrations, suggesting that DOC production may be related to both reducing conditions and mineral dissolution over time.

  12. BOREAS RSS-17 1994 ERS-1 Level-3 Freeze/Thaw Backscatter Change Images

    Science.gov (United States)

    Rignot, Eric; Nickeson, Jaime (Editor); Hall, Forrest G. (Editor); Way, JoBea; McDonald, Kyle C.; Smith, David E. (Technical Monitor)

    2000-01-01

    The Boreal Ecosystem-Atmosphere Study (BOREAS) Remote Sensing Science (RSS)-17 team acquired and analyzed imaging radar data from the European Space Agency's (ESA's) European Remote Sensing Satellite (ERS)-1 over a complete annual cycle at the BOREAS sites in Canada in 1994 to detect shifts in radar backscatter related to varying environmental conditions. Two independent transitions corresponding to soil thaw and possible canopy thaw were revealed by the data. The results demonstrated that radar provides an ability to observe thaw transitions at the beginning of the growing season, which in turn helps constrain the length of the growing season. The data set presented here includes change maps derived from radar backscatter images that were mosaicked together to cover the southern BOREAS sites. The image values used for calculating the changes are given relative to the reference mosaic image. The data are stored in binary image format files. The imaging radar data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files are available on a CD-ROM (see document number 20010000884).

  13. Effect of freezing on electrical properties and quality of thawed chicken breast meat

    Directory of Open Access Journals (Sweden)

    Ran Wei

    2017-04-01

    Full Text Available Objective The objective of this research was to study the electrical properties and quality of frozen-thawed chicken breast meat and to investigate the relationship between these parameters at different times of frozen storage. Methods Thawed samples of chicken breast muscles were evaluated after being kept in frozen storage at −18°C for different periods of time (1, 2, 3, 4, 5, 6, 7, and 8 months. Results The results showed that water-holding capacity (WHC and protein solubility decreased while thiobarbituric acid-reactive substances content increased with increasing storage time. The impedance module of samples decreased during 8-month frozen storage. Pearson correlation coefficients showed that the impedance change ratio (Q value was significantly (p<0.05 related to pH, color, WHC, lipid oxidation and protein solubility, indicating a good relationship between the electrical properties and qualities of frozen-thawed chicken breast meat. Conclusion Impedance measurement has a potential to assess the quality of frozen chicken meat combining with quality indices.

  14. Limited contribution of permafrost carbon to methane release from thawing peatlands

    Science.gov (United States)

    Cooper, Mark D. A.; Estop-Aragonés, Cristian; Fisher, James P.; Thierry, Aaron; Garnett, Mark H.; Charman, Dan J.; Murton, Julian B.; Phoenix, Gareth K.; Treharne, Rachael; Kokelj, Steve V.; Wolfe, Stephen A.; Lewkowicz, Antoni G.; Williams, Mathew; Hartley, Iain P.

    2017-07-01

    Models predict that thaw of permafrost soils at northern high latitudes will release tens of billions of tonnes of carbon (C) to the atmosphere by 2100 (refs ,,). The effect on the Earth’s climate depends strongly on the proportion of this C that is released as the more powerful greenhouse gas methane (CH4), rather than carbon dioxide (CO2) (refs ,); even if CH4 emissions represent just 2% of the C release, they would contribute approximately one-quarter of the climate forcing. In northern peatlands, thaw of ice-rich permafrost causes surface subsidence (thermokarst) and water-logging, exposing substantial stores (tens of kilograms of C per square meter, ref. ) of previously frozen organic matter to anaerobic conditions, and generating ideal conditions for permafrost-derived CH4 release. Here we show that, contrary to expectations, although substantial CH4 fluxes (>20 g CH4 m-2 yr-1) were recorded from thawing peatlands in northern Canada, only a small amount was derived from previously frozen C (emissions from northern peatlands.

  15. Consumer food handling recommendations: is thawing of turkey a food safety issue?

    Science.gov (United States)

    Lacroix, Bonnie Jeannette; Li, Kelly Wing Man; Powell, Douglas Alan

    2003-01-01

    While it is important that dietitians and other health or food professionals provide consistent messages to the public about food safety, it is equally important that the information be evidence-based. Conflicting recommendations are evident when reviewing consumer publications from food safety advisory groups and the scientific literature. In addition, caveats are attached to the various food-handling methods. Pathogens, spoilage microorganisms, and contamination of the work area are the major concerns in thawing turkey. While several methods, including thawing on the counter at ambient temperatures, can be employed for thawing turkey, cooking to an adequate internal temperature, validated with a meat thermometer, is the more critical step. The findings indicate that providing clients or consumers with clear, consistent, evidence-based messages is difficult for food and health professionals. Further research is required to corroborate best practices in a kitchen setting. This paper is of interest to professionals who counsel clients at high risk for foodborne illness, or who counsel consumers about safe preparation of foods such as turkey.

  16. Thermal Destabilization of Collagen Matrix Hierarchical Structure by Freeze/Thaw

    Science.gov (United States)

    Ozcelikkale, Altug; Han, Bumsoo

    2016-01-01

    This study aims to characterize and understand the effects of freezing on collagen structures and functionality. Specifically, thermodynamic destabilization of collagen at molecular- and fibril-levels by combination of low temperatures and freezing were experimentally characterized using modulated differential scanning calorimetry. In order to delineate the effects of sub-zero temperature and water-ice phase change, we hypothesized that the extent of destabilization can be determined based on post-thaw heat induced thermal denaturation of collagen. It is found that thermal denaturation temperature of collagen in hydrogel decreases by 1.4–1.6°C after freeze/thaw while no such decrease is observed in the case of molecular solution. The destabilization is predominantly due to ice formation. Exposure to low temperatures in the absence of ice has only minimal effect. Calorimetry measurements combined with morphological examination of collagen matrices by scanning electron microscopy suggest that freezing results in destabilization of collagen fibrils due to expansion of intrafibrillar space by ice formation. This fibril-level damage can be alleviated by use of cryoprotectant DMSO at concentrations as low as 0.5 M. A theoretical model explaining the change in collagen post-thaw thermal stability by freezing-induced fibril expansion is also proposed. PMID:26765741

  17. Effect of Freezing Rate and Microwave Thawing on Texture and Microstructural Properties of Potato (Solanum tuberosum).

    Science.gov (United States)

    Phinney, David M; Frelka, John C; Wickramasinghe, Anita; Heldman, Dennis R

    2017-04-01

    Food freezing is a preservation process that works by lowering temperature while simultaneously decreasing water activity. It is accepted that although freezing preserves foods, it generally has a negative effect on textural quality. This research investigated the texture response of potatoes (Solanum tuberosum) as a function of time to freeze (defined as the time for the center temperature to reach -20 °C) and thawing process. Potatoes slices (6 mm) were blanched then frozen in an ethanol/carbon dioxide bath, a pilot scale high velocity air freezer (HVAF) and a still air freezer to achieve various times to freeze. Slices were stabilized at -20 °C and thawed by 2 methods; room temperature air and microwave. Afterwards, samples were allowed to come to room temperature prior to texture profile analysis (TPA). Results indicate a maximum texture loss of the potato was reached at a time to freeze of approximately 8 min (corresponding to the HVAF). The texture difference between room temperature and microwave thawing methods was not shown to be significant (P = 0.05). SEM images showed the cellular structure of the potato in a HVAF to be similar to that of the still air freezer, validating that the matrix was maximally damaged in both conditions. This work created a continuous quality loss model for the potato as a function of time to freeze and showed no textural benefit to high velocity over still air freezing. © 2017 Institute of Food Technologists®.

  18. Estimation of thawing cryolithic area with numerical modeling in 3D geometry while exploiting underground small nuclear power plant

    Directory of Open Access Journals (Sweden)

    Melnikov N. N.

    2016-03-01

    Full Text Available The paper presents results on 3D numerical calculation of a thermal task related to assessing a thawing area when placing modules with reactor and steam-turbine facility of a small nuclear power plant in thickness of permafrost rocks. The paper discusses influence of the coefficient of thermal conductivity for large-scaled underground excavations lining and cryolithic area porosity on thawing depth and front movement velocity under different spatial directions

  19. Using Distributed Fiber Optic Sensing to Monitor Large Scale Permafrost Transitions: Preliminary Results from a Controlled Thaw Experiment

    Science.gov (United States)

    Ajo Franklin, J. B.; Wagner, A. M.; Lindsey, N.; Dou, S.; Bjella, K.; Daley, T. M.; Freifeld, B. M.; Ulrich, C.; Gelvin, A.; Morales, A.; James, S. R.; Saari, S.; Ekblaw, I.; Wood, T.; Robertson, M.; Martin, E. R.

    2016-12-01

    In a warming world, permafrost landscapes are being rapidly transformed by thaw, yielding surface subsidence and groundwater flow alteration. The same transformations pose a threat to arctic infrastructure and can induce catastrophic failure of the roads, runways, and pipelines on which human habitation depends. Scalable solutions to monitoring permafrost thaw dynamics are required to both quantitatively understand biogeochemical feedbacks as well as to protect built infrastructure from damage. Unfortunately, permafrost alteration happens over the time scale of climate change, years to decades, a decided challenge for testing new sensing technologies in a limited context. One solution is to engineer systems capable of rapidly thawing large permafrost units to allow short duration experiments targeting next-generation sensing approaches. We present preliminary results from a large-scale controlled permafrost thaw experiment designed to evaluate the utility of different geophysical approaches for tracking the cause, precursors, and early phases of thaw subsidence. We focus on the use of distributed fiber optic sensing for this challenge and deployed distributed temperature (DTS), strain (DSS), and acoustic (DAS) sensing systems in a 2D array to detect thaw signatures. A 10 x 15 x 1 m section of subsurface permafrost was heated using an array of 120 downhole heaters (60 w) at an experimental site near Fairbanks, AK. Ambient noise analysis of DAS datasets collected at the plot, coupled to shear wave inversion, was utilized to evaluate changes in shear wave velocity associated with heating and thaw. These measurements were confirmed by seismic surveys collected using a semi-permanent orbital seismic source activated on a daily basis. Fiber optic measurements were complemented by subsurface thermistor and thermocouple arrays, timelapse total station surveys, LIDAR, secondary seismic measurements (geophone and broadband recordings), timelapse ERT, borehole NMR, soil

  20. Chemical Structure of the Lipid A component of Pseudomonas sp. strain PAMC 28618 from Thawing Permafrost in Relation to Pathogenicity

    OpenAIRE

    Han-Gyu Park; Ganesan Sathiyanarayanan; Cheol-Hwan Hwang; Da-Hee Ann; Jung-Ho Kim; Geul Bang; Kyoung-Soon Jang; Hee Wook Ryu; Yoo Kyung Lee; Yung-Hun Yang; Yun-Gon Kim

    2017-01-01

    Climate change causes permafrost thawing, and we are confronted with the unpredictable risk of newly discovered permafrost microbes that have disease-causing capabilities. Here, we first characterized the detailed chemical structure of the lipid A moiety from a Pseudomonas species that was isolated from thawing arctic permafrost using MALDI-based mass spectrometric approaches (i.e., MALDI-TOF MS and MALDI-QIT-TOF MSn). The MALDI multi-stage mass spectrometry (MS) analysis of lipid A extracted...

  1. Response of Soil Biogeochemistry to Freeze-thaw Cycles: Impacts on Greenhouse Gas Emission and Nutrient Fluxes

    Science.gov (United States)

    Rezanezhad, F.; Parsons, C. T.; Smeaton, C. M.; Van Cappellen, P.

    2014-12-01

    Freeze-thaw is an abiotic stress applied to soils and is a natural process at medium to high latitudes. Freezing and thawing processes influence not only the physical properties of soil, but also the metabolic activity of soil microorganisms. Fungi and bacteria play a crucial role in soil organic matter degradation and the production of greenhouse gases (GHG) such as CO2, CH4 and N2O. Production and consumption of these atmospheric trace gases are the result of biological processes such as photosynthesis, aerobic respiration (CO2), methanogenesis, methanotrophy (CH4), nitrification and denitrification (N2O). To enhance our understanding of the effects of freeze-thaw cycles on soil biogeochemical transformations and fluxes, a highly instrumented soil column experiment was designed to realistically simulate freeze-thaw dynamics under controlled conditions. Pore waters collected periodically from different depths of the column and solid-phase analyses on core material obtained at the initial and end of the experiment highlighted striking geochemical cycling. CO2, CH4 and N2O production at different depths within the column were quantified from dissolved gas concentrations in pore water. Subsequent emissions from the soil surface were determined by direct measurement in the head space. Pulsed CO2 emission to the headspace was observed at the onset of thawing, however, the magnitude of the pulse decreased with each subsequent freeze-thaw cycle indicating depletion of a "freeze-thaw accessible" carbon pool. Pulsed CO2 emission was due to a combination of physical release of gases dissolved in porewater and entrapped below the frozen zone and changing microbial respiration in response to electron acceptor variability (O2, NO3-, SO42-). In this presentation, we focus on soil-specific physical, chemical, microbial factors (e.g. redox conditions, respiration, fermentation) and the mechanisms that drive GHG emission and nutrient cycling in soils under freeze-thaw cycles.

  2. Oolitic limestone and marine sandstone gravel aggregate \\ud Early life concrete and aggregate freeze/thaw test for durability

    OpenAIRE

    Richardson, Alan; Hemapanpairo, Kawin; Sae-Tae, Thotsaphorn; Puthipad, Nipat; Northumbria University, UK; Thammasat University, Rangsit, Thailand

    2011-01-01

    Oolitic limestone is one type of limestone which formed during the Jurassic period and can be found in large deposits in many areas of England. It can be used as coarse aggregate for concrete construction, however due to its porosity, it requires additional cement to maintain compressive strength, when compared to marine gravel (sandstone) concrete. Since freeze/thaw durability is one of the most common problems in temperate countries, this paper investigates the freeze/thaw resistance of Ool...

  3. Short communication: Effect of freezer storage time and thawing method on the recovery of Mycoplasma bovis from bovine colostrum.

    Science.gov (United States)

    Gille, L; Boyen, F; Van Driessche, L; Valgaeren, B; Haesebrouck, F; Deprez, P; Pardon, B

    2017-10-25

    Mycoplasma bovis is an important cause of mastitis in dairy cattle, and pneumonia, arthritis, and otitis in calves. Milk and colostrum are considered important sources of infection for calves. Knowledge on the effect of on-farm freezing (-18°C) and thawing methods on the recovery of M. bovis from colostrum samples is missing. In this study, 2 separate experiments were performed. The first experiment consisted of a longitudinal study examining the survival [as measured by log(10) reduction] of 2 M. bovis strains in frozen colostrum over 14 wk. The second experiment examined the effect of different thawing temperatures (45 and 20°C), thawing frequencies (once or twice), and initial colostrum titer (10(4) or 10(6) cfu/mL) on M. bovis survival. A single freeze-thaw cycle led to an approximate 1 log reduction of M. bovis titer, independent of the thawing temperature. Freezing for 14 wk did not significantly further reduce the titer of bacteria compared with freezing for 2 wk. A second freeze-thaw cycle further reduced the M. bovis count by approximately 0.5 log compared with a single freeze-thaw cycle. Thawing temperature and initial bacterial concentration did not significantly affect M. bovis reduction. In conclusion, storage of colostrum samples in the freezer at -18°C during epidemiological studies, herd monitoring, or test and cull programs will probably have little influence on qualitative bacteriological test results for M. bovis. The epidemiological or clinical relevance of an approximate 1 log reduction of M. bovis in colostrum is currently unclear. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  4. Effects of permafrost thaw on CO2 and CH4 exchange in a western Alaska peatland chronosequence

    Science.gov (United States)

    Carmel E. Johnston,; Stephanie A. Ewing,; Harden, Jennifer W.; Ruth K. Varner,; Wickland, Kimberly P.; Koch, Joshua C.; Fuller, Christopher C.; Manies, Kristen L.; M. Torre Jorgenson,

    2014-01-01

    Permafrost soils store over half of global soil carbon (C), and northern frozen peatlands store about 10% of global permafrost C. With thaw, inundation of high latitude lowland peatlands typically increases the surface-atmosphere flux of methane (CH4), a potent greenhouse gas. To examine the effects of lowland permafrost thaw over millennial timescales, we measured carbon dioxide (CO2) and CH4 exchange along sites that constitute a ~1000 yr thaw chronosequence of thermokarst collapse bogs and adjacent fen locations at Innoko Flats Wildlife Refuge in western Alaska. Peak CH4exchange in July (123 ± 71 mg CH4–C m−2 d−1) was observed in features that have been thawed for 30 to 70 (permafrost thaw are enhanced over decadal time scales, but limited over millennia. Over larger spatial scales, adjacent fen systems may contribute sustained CH4 emission, CO2 uptake, and DOC export. We argue that over timescales of decades to centuries, thaw features in high-latitude lowland peatlands, particularly those developed on poorly drained mineral substrates, are a key locus of elevated CH4 emission to the atmosphere that must be considered for a complete understanding of high latitude CH4 dynamics.

  5. Colloid single-layer centrifugation improves post-thaw donkey (Equus asinus) sperm quality and is related to ejaculate freezability.

    Science.gov (United States)

    Ortiz, I; Dorado, J; Acha, D; Gálvez, M J; Urbano, M; Hidalgo, M

    2015-01-01

    The aim of this study was to determine whether colloid single-layer centrifugation (SLC) improves post-thaw donkey sperm quality and if this potential enhancement is related to ejaculate freezability. Semen from Andalusian donkeys was frozen following a standard protocol. SLC was performed on frozen-thawed semen and post-thaw sperm parameters were compared with uncentrifuged samples. Sperm quality was estimated by integrating in a single value sperm motility (assessed by computer-assisted sperm analysis), morphology and viability (evaluated under brightfield or fluorescence microscopy). Sperm freezability was calculated as the relationship between sperm quality obtained before freezing and after thawing. Ejaculates were classified into low, medium and high freezability groups using the 25th and 75th percentiles as thresholds. All sperm parameters were significantly (P<0.01) higher in SLC-selected samples in comparison to uncentrifuged frozen-thawed semen and several kinematic parameters were even higher than those obtained in fresh semen. The increment of sperm parameters after SLC selection was correlated with ejaculate freezability, obtaining the highest values after SLC in semen samples with low freezability. We concluded that, based on the sperm-quality parameters evaluated, SLC can be a suitable procedure to improve post-thaw sperm quality of cryopreserved donkey semen, in particular for those ejaculates with low freezability.

  6. Freeze-Thaw Stress: Effects of Temperature on Hydraulic Conductivity and Ultrasonic Activity in Ten Woody Angiosperms1

    Science.gov (United States)

    Charrier, Guillaume; Charra-Vaskou, Katline; Kasuga, Jun; Cochard, Hervé; Mayr, Stefan; Améglio, Thierry

    2014-01-01

    Freeze-thaw events can affect plant hydraulics by inducing embolism. This study analyzed the effect of temperature during the freezing process on hydraulic conductivity and ultrasonic emissions (UE). Stems of 10 angiosperms were dehydrated to a water potential at 12% percentage loss of hydraulic conductivity (PLC) and exposed to freeze-thaw cycles. The minimal temperature of the frost cycle correlated positively with induced PLC, whereby species with wider conduits (hydraulic diameter) showed higher freeze-thaw-induced PLC. Ultrasonic activity started with the onset of freezing and increased with decreasing subzero temperatures, whereas no UE were recorded during thawing. The temperature at which 50% of UE were reached varied between −9.1°C and −31.0°C across species. These findings indicate that temperatures during freezing are of relevance for bubble formation and air seeding. We suggest that species-specific cavitation thresholds are reached during freezing due to the temperature-dependent decrease of water potential in the ice, while bubble expansion and the resulting PLC occur during thawing. UE analysis can be used to monitor the cavitation process and estimate freeze-thaw-induced PLC. PMID:24344170

  7. Sperm characteristics and in vitro fertilization ability of thawed spermatozoa from Black Manchega ram: electroejaculation and postmortem collection.

    Science.gov (United States)

    García-Alvarez, O; Maroto-Morales, A; Martínez-Pastor, F; Garde, J J; Ramón, M; Fernández-Santos, M R; Esteso, M C; Pérez-Guzmán, M D; Soler, A J

    2009-07-15

    The aim of this study was to assess two models of sperm collection on the quality and fertility of thawed spermatozoa from Black Manchega rams, a threatened breed. Sperm samples were collected by electroejaculation and postmortem from each male. Samples were diluted with Biladyl and frozen. Motility (subjective and objective by means of computer-assisted semen analysis), membrane integrity, and acrosomal status (microscopy) were assessed on fresh and thawed semen; plasmalemma integrity, mitochondrial membrane potential, DNA integrity, and acrosomal status were evaluated by flow cytometry on thawed semen. Thawed spermatozoa were used in a heterologous in vitro fertilization test. After thawing, the proportion of live spermatozoa with intact membrane (YO-PRO-1-/PI-) was higher for postmortem samples (Pelectroejaculated samples (P=0.026 and P=0.003). Both electroejaculated and postmortem samples fertilized oocytes. Nevertheless, electroejaculated samples yielded a higher percentage of hybrid embryos (P=0.041). In conclusion, although postmortem spermatozoa had better sperm quality after thawing, electroejaculated spermatozoa showed higher ratios for sperm quality when only the live population was considered. Electroejaculated and postmortem samples might be used for germplasm banking of this threatened breed, but the fertility of postmortem spermatozoa might be lower.

  8. Effects of repetitive freeze–thawing cycles on T2 and T2* of the Achilles tendon

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Eric Y., E-mail: ericchangmd@gmail.com [Department of Radiology, VA San Diego Healthcare System, 3350 La Jolla Village Drive, San Diego, CA 92161 (United States); Department of Radiology, University of California, 200 West Arbor St., San Diego, CA 92103 (United States); Bae, Won C., E-mail: wbae@ucsd.edu [Department of Radiology, University of California, 200 West Arbor St., San Diego, CA 92103 (United States); Statum, Sheronda, E-mail: sherondastatum@msn.com [Department of Radiology, University of California, 200 West Arbor St., San Diego, CA 92103 (United States); Du, Jiang, E-mail: jiangdu@ucsd.edu [Department of Radiology, University of California, 200 West Arbor St., San Diego, CA 92103 (United States); Chung, Christine B., E-mail: cbchung@ucsd.edu [Department of Radiology, University of California, 200 West Arbor St., San Diego, CA 92103 (United States); Department of Radiology, VA San Diego Healthcare System, 3350 La Jolla Village Drive, San Diego, CA 92161 (United States)

    2014-02-15

    Introduction: In this study we sought to evaluate the effects of multiple freezing and thawing cycles on two MR parameters to study Achilles tendon, T2 and T2*. Materials and methods: Four fresh Achilles tendons were imaged on a 3T clinical scanner and again after 1, 2, 4, and 5 freeze–thaw cycles with spin-echo (SE) and ultrashort echo time (UTE) sequences. Regions of interest were manually drawn over the entire Achilles tendon and mono-exponential curves were used to determine T2 and T2* relaxation times. Results: There was no statistically significant difference in mean T2 or T2* values between the fresh specimens and after subsequent cycles of freeze–thaw treatment (p > 0.1). Linear regression between SE T2 values at baseline and after successive freeze–thaw cycles demonstrated moderate agreement (r = 0.60) whereas UTE T2* values at baseline and after successive-freeze thaw cycles demonstrated strong agreement (r = 0.92). Conclusion: These findings suggest that changes between specimens seen in vitro are due to factors other than frozen storage. Furthermore, our results suggest that there is stronger agreement between baseline (fresh) and successive freeze–thaw T2* values of tendon obtained with the UTE technique in comparison to T2 values obtained with a conventional clinical CPMG technique.

  9. Evaluation of Spaceborne L-band Radiometer Measurements for Terrestrial Freeze/Thaw Retrievals in Canada

    Science.gov (United States)

    Roy, A.; Royer, A.; Derksen, C.; Brucker, L.; Langlois, A.; Mailon, A.; Kerr, Y.

    2015-01-01

    The landscape freeze/thaw (FT) state has an important impact on the surface energy balance, carbon fluxes, and hydrologic processes; the timing of spring melt is linked to active layer dynamics in permafrost areas. L-band (1.4 GHz) microwave emission could allow the monitoring of surface state dynamics due to its sensitivity to the pronounced permittivity difference between frozen and thawed soil. The aim of this paper is to evaluate the performance of both Aquarius and Soil Moisture and Ocean Salinity (SMOS) L-band passive microwave measurements using a polarization ratio-based algorithm for landscape FT monitoring. Weekly L-band satellite observations are compared with a large set of reference data at 48 sites across Canada spanning three environments: tundra, boreal forest, and prairies. The reference data include in situ measurements of soil temperature (Tsoil) and air temperature (Tair), and Moderate Resolution Imaging Spectroradiometer (MODIS) land surface temperature (LST) and snow cover area (SCA) products. Results show generally good agreement between Lband FT detection and the surface state estimated from four reference datasets. The best apparent accuracies for all seasons are obtained using Tair as the reference. Aquarius radiometer 2 (incidence angle of 39.6) data gives the best accuracies (90.8), while for SMOS the best results (87.8 of accuracy) are obtained at higher incidence angles (55- 60). The FT algorithm identifies both freeze onset and end with a delay of about one week in tundra and two weeks in forest and prairies, when compared to Tair. The analysis shows a stronger FT signal at tundra sites due to the typically clean transitions between consistently frozen and thawed conditions (and vice versa) and the absence of surface vegetation. Results in the prairies were poorer because of the influence of vegetation growth in summer (which decreases the polarization ratio) and the high frequency of ephemeral thaw events during winter. Freeze onset

  10. Fifty years of coastal erosion and retrogressive thaw slump activity on Herschel Island, southern Beaufort Sea, Yukon Territory, Canada

    Science.gov (United States)

    Lantuit, H.; Pollard, W. H.

    2008-03-01

    Patterns of coastal erosion in the Arctic differ dramatically from those coasts in more temperate environments. Thick sea ice and shore-fast ice limit wave-based erosional processes to a brief open water season, however despite this, permafrost coasts containing massive ice, ice wedges and ice-bonded sediments tend to experience high rates of erosion. These high rates of erosion reflect the combined thermal-mechanical processes of thawing permafrost, melting ground ice, and wave action. Climate change in the Arctic is expected to result in increased rates of coastal erosion due to warming permafrost, increasing active layer depths and thermokarst, rising sea levels, reduction in sea ice extent and duration, and increasing storm impacts. With the most ice-rich permafrost in the Canadian Arctic, the southern Beaufort Sea coast between the Tuktoyaktuk Peninsula and the Alaskan border is subject to high rates of erosion and retrogressive thaw slump activity. Under many climate change scenarios this area is also predicted to experience the greatest warming in the Canadian Arctic. This paper presents results of a remote sensing study on the long-term patterns of coastal erosion and retrogressive thaw slump activity for Herschel Island in the northern Yukon Territory. Using orthorectified airphotos from 1952 and 1970 and an Ikonos image from 2000 corrected with control points collected by kinematic differential global positioning system and processed using softcopy photogrammetric tools, mean coastal retreat rates of 0.61 m/yr and 0.45 m/yr were calculated for the periods 1952-1970 and 1970-2000, respectively. The highest coastal retreat rates are on north-west facing shorelines which correspond to the main direction of storm-related wave attack. During the period 1970-2000 coastal retreat rates for south to south-east facing shorelines displayed a distinct increase even though these are the most sheltered orientations. However, south to south-east facing shorelines

  11. Sperm preparation after freezing improves motile sperm count, motility, and viability in frozen-thawed sperm compared with sperm preparation before freezing-thawing process.

    Science.gov (United States)

    Palomar Rios, A; Gascón, A; Martínez, J V; Balasch, S; Molina Botella, I

    2017-10-09

    The aim of this study is to evaluate which cryopreservation protocol, freezing before or after swim-up, optimizes cryopreservation outcomes in terms of motile sperm count, motility, morphology, and viability, and also to establish whether sperm viability could be assessed based on sperm motility. Fifty-three fresh and 53 swim-up prepared samples were considered for the first experiment. In parallel, total motility evaluation by CASA system (computer-assisted sperm analyzer) and hypoosmotic swelling test (HOS-test) was performed in each sample to compare the viability results of both methods. In the second experiment, 21 normozoospermic semen samples and 20 semen samples from male factor patients were included. After fresh ejaculate evaluation, the semen sample of each patient was divided into two aliquots, one of them was frozen before swim-up and the other was frozen after swim-up. Motility, sperm count, morphology, and viability were evaluated after thawing. A linear regression model allows prediction of HOS-test viability results based on total motility: HOS = 1.38 + 0.97 · TM (R (2) = 99.10, residual mean squares = 9.51). Freezing before sperm selection leads to higher total and progressive motility, total motile sperm count, and viability rates than when sperm selection is performed before freezing (P < 0.005 in all cases). In fact, sperm selection prior to freezing reaches critical values when subfertile patients are considered. To conclude, total motility evaluation can predict HOS-test viability results, resulting in a more objective and less time-consuming method to assess viability. In addition, sperm freezing prior to swim-up selection must be considered in order to achieve better outcomes after thawing, especially in patients presenting poor sperm baseline.

  12. Snowmelt and Surface Freeze/Thaw Timings over Alaska derived from Passive Microwave Observations using a Wavelet Classifier

    Science.gov (United States)

    Steiner, N.; McDonald, K. C.; Dinardo, S. J.; Miller, C. E.

    2015-12-01

    Arctic permafrost soils contain a vast amount of organic carbon that will be released into the atmosphere as carbon dioxide or methane when thawed. Surface to air greenhouse gas fluxes are largely dependent on such surface controls as the frozen/thawed state of the snow and soil. Satellite remote sensing is an important means to create continuous mapping of surface properties. Advances in the ability to determine soil and snow freeze/thaw timings from microwave frequency observations improves upon our ability to predict the response of carbon gas emission to warming through synthesis with in-situ observation, such as the 2012-2015 Carbon in Arctic Reservoir Vulnerability Experiment (CARVE). Surface freeze/thaw or snowmelt timings are often derived using a constant or spatially/temporally variable threshold applied to time-series observations. Alternately, time-series singularity classifiers aim to detect discontinuous changes, or "edges", in time-series data similar to those that occur from the large contrast in dielectric constant during the freezing or thaw of soil or snow. We use multi-scale analysis of continuous wavelet transform spectral gradient brightness temperatures from various channel combinations of passive microwave radiometers, Advanced Microwave Scanning Radiometer (AMSR-E, AMSR2) and Special Sensor Microwave Imager (SSM/I F17) gridded at a 10 km posting with resolution proportional to the observational footprint. Channel combinations presented here aim to illustrate and differentiate timings of "edges" from transitions in surface water related to various landscape components (e.g. snow-melt, soil-thaw). To support an understanding of the physical basis of observed "edges" we compare satellite measurements with simple radiative transfer microwave-emission modeling of the snow, soil and vegetation using in-situ observations from the SNOw TELemetry (SNOTEL) automated weather stations. Results of freeze/thaw and snow-melt timings and trends are

  13. Effect of repeated freeze-thaw cycles on geographically different populations of the freeze-tolerant worm Enchytraeus albidus (Oligochaeta).

    Science.gov (United States)

    Fisker, Karina Vincents; Holmstrup, Martin; Malte, Hans; Overgaard, Johannes

    2014-11-01

    Freeze-tolerant organisms survive internal ice formation; however, the adaptations to repeated freeze-thaw cycles are often not well investigated. Here we report how three geographically different populations of Enchytraeus albidus (Germany, Iceland and Svalbard) respond to three temperature treatments - constant thawed (0°C), constant freezing (-5°C) and fluctuating temperature (0 to -5°C) - over a period of 42 days. Survival varied between treatments and populations such that enchytraeids from arctic locations had a higher survival following prolonged freeze periods compared with temperate populations. However, enchytraeids from temperate locations had the same survival rate as arctic populations when exposed to repeated freeze-thaw events. Across all populations, metabolic rate decreased markedly in frozen animals (-5°C) compared with thawed controls (0°C). This decrease is likely due to the lower temperature of frozen animals, but also to the transition to the frozen state per se. Animals exposed to repeated freeze-thaw events had an intermediate metabolic rate and freeze-thaw events were not associated with pronounced excess energetic costs. Overwintering under either condition was not associated with a decrease in lipid content; however, during exposure to constant freezing and repeated freeze-thaw events there was a noticeable decrease in carbohydrate stores over time. Thus, animals exposed to constant freezing showed a decrease in glycogen stores, while both glucose and glycogen content decreased over time when the organisms were exposed to repeated freezing. The results therefore suggest that carbohydrate resources are important as a fuel for E. albidus during freezing whereas lipid resources are of marginal importance. © 2014. Published by The Company of Biologists Ltd.

  14. Comparative cryopreservation of avian spermatozoa: effects of freezing and thawing rates on turkey and sandhill crane sperm cryosurvival.

    Science.gov (United States)

    Blanco, Juan M; Long, Julie A; Gee, George; Wildt, David E; Donoghue, Ann M

    2012-03-01

    A comparative approach was used to evaluate semen cooling rates, thawing rates and freezing volume on the cryosurvival of avian sperm. Turkey (Meleagris gallopavo) and sandhill crane (Grus canadensis) sperm were cryopreserved with dimethylacetamide (DMA) concentrations ranging from 6% to 26%. Experiments evaluated the efficacy of (1) rapid, moderate and slow cooling rates, (2) rapid and slow thawing rates, and (3) final volume of semen frozen (0.2 mL compared to 0.5 mL). For crane sperm only, additional experiments were conducted to evaluate the effect of sucrose on cryosurvival. The functionality of frozen/thawed crane sperm was evaluated by fertility trials. For all studies, sperm viability was assessed using the nigrosin-eosin stain. Higher percentages of crane and turkey sperm maintained intact membranes when frozen with moderate or slow cooling rates compared to rapid cooling rates (P0.05). Crane sperm viability was only affected by thawing rate for the 24% DMA treatment, where moderate thawing was better than slow thawing (P0.05). The percentage of membrane-intact crane sperm at lower DMA concentrations was improved by addition of 0.1M sucrose (Pcrane semen was 57.5%, and 71.4% of the fertile eggs hatched. The viability of crane sperm was always greater than turkey sperm, regardless of cooling rate, thawing rate or volume of semen frozen. These data verify avian-specific differences in sperm cryosurvival, further emphasize the need for species specific studies to optimize cryopreservation protocols. Copyright © 2012. Published by Elsevier B.V.

  15. The fate of 13C15N labelled glycine in permafrost and surface soil at simulated thaw in mesocosms from high arctic and subarctic ecosystems

    DEFF Research Database (Denmark)

    Ravn, Nynne Marie Rand; Elberling, Bo; Michelsen, Anders

    2017-01-01

    glycine addition. Results: Near-surface soil microbes were more efficient in the uptake of intact glycine immediately upon thaw than plants. After one month plants had gained more 15N whereas microbes seemed to lose 15N originating from glycine. We observed a time lag in glycine degradation upon...... compound in thawing permafrost and surface soil. Methods: Double labeled glycine (13C15N) was added to soil columns with vegetation and to permafrost. During thaw conditions ecosystem respiration 13C was measured and 13C and 15N distribution in the ecosystem pools was quantified one day and one month after...... permafrost thaw, in contrast to surface soil thaw. Conclusions: Our results suggest that both arctic plants and microorganisms acquire amino acids released upon spring and permafrost thaw. Despite indications of more efficient utilization of added substrate in the High Arctic than the Subarctic, we conclude...

  16. Effect of wildfire and fireline construction on the annual depth of thaw in a black spruce permafrost forest in interior Alaska: a 36-year record of recovery

    Science.gov (United States)

    Leslie A. Viereck; Nancy R. Werdin-Pfisterer; Phyllis C. Adams; Kenji Yoshikawa

    2008-01-01

    Maximum thaw depths were measured annually in an unburned stand, a heavily burned stand, and a fireline in and adjacent to the 1971 Wickersham fire. Maximum thaw in the unburned black spruce stand ranged from 36 to 52 cm. In the burned stand, thaw increased each year to a maximum depth of 302 cm in 1995. In 1996, the entire layer of seasonal frost remained, creating a...

  17. Nuclear magnetic resonance analysis of freeze-thaw damage in natural pumice concrete

    Directory of Open Access Journals (Sweden)

    Wang, Xiaoxiao

    2016-06-01

    Full Text Available This paper presents an analysis of the damage propagation features of the pore structure of natural pumice lightweight aggregate concrete (LWC under freeze-thaw cyclic action. After freeze-thaw cycling, we conducted nuclear magnetic resonance (NMR tests on the concrete and acquired the porosity, distribution of transverse relaxation time T2, and magnetic resonance imaging (MRI results. The results showed the following. The T2 distribution of the LWC prior to freeze-thaw cycling presented four peaks representative of a preponderance of small pores. After 50, 100, 150, and 200 freeze-thaw cycles, the total area of the T2 spectrum and the porosity increased significantly. The MRI presented the changing spatial distribution of pores within the LWC during freeze-thaw cycling. Ultrasonic testing technology was applied simultaneously to analyze the NMR results, which verified that the new NMR technology demonstrated high accuracy and practicability for research regarding freeze-thaw concrete damage.En este trabajo se analiza la propagación de los daños que se producen en la estructura porosa de hormigón aligerado a base de piedra pómez natural sometido a la acción cíclica de hielo-deshielo. Después de realizarse los ensayos de hielo-deshielo, el hormigón se analizó mediante resonancia magnética nuclear (RMN, determinándose la porosidad y la distribución del tiempo de relajación transversal, T2, y registrándose las imágenes captadas por resonancia magnética. De acuerdo con los resultados obtenidos, antes de los ciclos de hielo-deshielo la distribución de T2 del hormigón aligerado presentaba cuatro picos, indicativos de un predominio de poros pequeños. Después de que se sometiera a 50, 100, 150, y 200 ciclos, se observó un aumento importante tanto de la porosidad como de la superficie total del espectro de T2. Las imágenes captadas por resonancia magnética evidenciaron la modificación de la distribución espacial de los poros del

  18. Combined Effect of Trolox and EDTA on Frozen-Thawed Sperm Quality

    Directory of Open Access Journals (Sweden)

    Sara Keshtgar

    2016-05-01

    Full Text Available The freezing and thawing process not only is associated with serious damage to sperm such as damage to the plasma membrane and the acrosomal membrane but also changes the membrane permeability to some ions including calcium. Also, the generation of oxygen free radicals is increased during the freezing-thawing process. The purpose of this study was to evaluate of the effects of Trolox as an antioxidant and edetic acid (EDTA as a calcium chelator on frozen-thawed (FT sperm and compare these effects with those on fresh sperm. This study was done on these men of 25 healthy men, who referred to Shiraz Infertility Centerbetween2012 and2013. Normal samples were transferred to the ReproductivePhysiology Laboratory, Department of Physiology,Shiraz University of Medical Sciences, Shiraz. The samples were divided into two groups randomly: fresh and FT sperm groups. Each group was divided into five subgroups: control group, the solvent group (0.1%dimethyl sulfoxide [DMSO], Trolox group (200μM, EDTA group (1.1mM, and Trolox+EDTA group. The percentages of motility, viability, and acrosome-reacted sperm were tested. The percentages of motility and viability in the FT sperm were lower than those in the fresh sperm. The progressive motility of the FT sperm was improved nonsignificantly with Trolox+EDTA. However, the effect of Trolox+EDTA on the progressive motility of the FT sperm was much more than that on the fresh sperm. The fewest acrosome-reacted sperm were observed in the EDTA-containingFT sperm. Antioxidant supplementation or omission of extracellular calcium may partly improve motility and also reduce acrosomal damage in FT sperm.

  19. Combined Effect of Trolox and EDTA on Frozen-Thawed Sperm Quality.

    Science.gov (United States)

    Keshtgar, Sara; Iravanpour, Farideh; Gharesi-Fard, Behrooz; Kazerooni, Marjaneh

    2016-05-01

    The freezing and thawing process not only is associated with serious damage to sperm such as damage to the plasma membrane and the acrosomal membrane but also changes the membrane permeability to some ions including calcium. Also, the generation of oxygen free radicals is increased during the freezing-thawing process. The purpose of this study was to evaluate of the effects of Trolox as an antioxidant and edetic acid (EDTA) as a calcium chelator on frozen-thawed (FT) sperm and compare these effects with those on fresh sperm. This study was done on these men of 25 healthy men, who referred to Shiraz Infertility Centerbetween2012 and2013. Normal samples were transferred to the ReproductivePhysiology Laboratory, Department of Physiology, Shiraz University of Medical Sciences, Shiraz. The samples were divided into two groups randomly: fresh and FT sperm groups. Each group was divided into five subgroups: control group, the solvent group (0.1%dimethyl sulfoxide [DMSO]), Trolox group (200μM), EDTA group (1.1mM), and Trolox+EDTA group. The percentages of motility, viability, and acrosome-reacted sperm were tested. The percentages of motility and viability in the FT sperm were lower than those in the fresh sperm. The progressive motility of the FT sperm was improved nonsignificantly with Trolox+EDTA. However, the effect of Trolox+EDTA on the progressive motility of the FT sperm was much more than that on the fresh sperm. The fewest acrosome-reacted sperm were observed in the EDTA-containingFT sperm. Antioxidant supplementation or omission of extracellular calcium may partly improve motility and also reduce acrosomal damage in FT sperm.

  20. Electron acceptor-based regulation of microbial greenhouse gas production from thawing permafrost

    Science.gov (United States)

    Bak, Ebbe; Jones, Eleanor; Yde, Jacob; Hodson, Andy; Mallon, Gunnar; Fisnter, Kai

    2017-04-01

    Permafrost contains about 35% of the global soil organic carbon (0-3 m depth). As a consequence of global warming, the active layer thickness is steadily increasing and its organic carbon is becoming available for degradation, causing a concomitant release of CO2 and CH4. The climate forcing feedbacks of permafrost thaw are determined by the rate of organic carbon degradation and to which degree it is released as CO2 or CH4. Methane is produced under anoxic conditions, but the factors that regulate its production are poorly constrained. In this study, we investigate how CH4 production is influenced by the presence of competing anaerobic processes with focus on the role of iron and sulfate reduction. We have collected permafrost cores to 2.2 meters depth from three different lowland sites in Adventdalen on Svalbard. From these cores, we have prepared anoxic batch incubation for each 25 cm depth interval and followed the production of CO2 and CH4 as well as the iron and sulfate reduction. This approach allows us to monitor the rate of the CO2 and CH4 production as well as to investigate the correlation between CH4 production and competing anaerobic respiration processes in the active layer as well in the permafrost. These investigations are accompanied by characterization of the carbon, iron and sulfate content in the soil and will be followed by characterization of the microbial community structure. The aim of this study is to get a better understanding of how the availability of sulfate and iron and the microbial community structure regulate the production of CO2 and CH4 in thawing permafrost, and to elucidate how the rate of the organic carbon degradation changes with depth in permafrost-affected soils. This study improves our understanding of climate feedback mechanisms operating during permafrost thaw.

  1. Polyvinyl alcohol/chitosan/montmorillonite nanocomposites preparation by freeze/thaw cycles and characterization

    Directory of Open Access Journals (Sweden)

    Părpăriţă Elena

    2014-12-01

    Full Text Available Polyvinyl alcohol (PVA and chitosan (CS based hydrogels are often chosen to obtain hydrogels as being considered non-toxic for human body. The present study aims the preparation and physical chemical characterisation of hydrogels based PVA and CS by using an environmental friendly method i.e. freeze/thaw. In this method the only parameters affecting the hydrogels’ properties is the PVA concentration in solution, time and number of cycles of freezing / thawing. Repeated freezing and thawing cycles resulted in production of a highly elastic polyvinyl alcohol hydrogel with higher degree of crystallization. Adding chitosan in polyvinyl alcohol hydrogel is giving to the newly formed material, biocompatibility and antibacterial properties due to the free amino groups of chitosan. Higher mechanical and thermal characteristics of PVA/CS based hydrogels were obtained by addition of a small amount of inorganic nanoparticles (montmorillonite clay, C30B into the matrix (i.e. 1%. Scanning electron microscopy (SEM, Fourier transform infrared spectroscopy (FT-IR, near-infrared chemical imaging spectroscopy (NI-CI, X-ray diffraction (XRD, thermogravimetric analysis (TG, swelling and rheological measurements were used to characterize the polyvinyl alcohol/chitosan/montmorillonite properties. The swelling degree increased with decreasing chitosan content in hydrogels and the variation is opposite in nanocomposites, decreasing after introducing the nanoclay. The swelling behaviour was influenced by the presence of the nanoparticles. The plasticizer effect of the nanoparticles was reflected by obtaining a more compact hydrogel network with higher mechanical and thermal properties. The proposed materials can be a promising alternative in biomedical applications

  2. L-Band Emission of Soil Freeze-Thaw State in a Tibetan Meadow Ecosystem

    Science.gov (United States)

    Zheng, Donghai; Wang, Xin; van der Velde, Rogier; Su, Zhongbo; Zeng, Yijian; Wen, Jun; Wang, Zuoliang; Schwank, Mike; Ferrazzoli, Paolo

    2017-04-01

    Soil freeze-thaw transition monitoring is essential for quantifying climate change and hydrologic dynamics over cold regions, for instance, the Tibetan Plateau. We investigate the L-band (1.4 GHz) microwave emission characteristics of soil freeze-thaw cycle via analysis of tower-based brightness temperature (TB) measurements using the ELBARA III radiometer in combination with simulations performed by a model of soil emission considering vertical variations of permittivity and soil temperature. Vegetation effects are modelled using the Tor Vergata discrete model. As part of Soil Moisture and Ocean Salinity (SMOS) and Soil Moisture Active Passive (SMAP) calibration and validation activities, the ELBARA III radiometer is installed on a 4.8 m high tower located in a seasonally frozen Tibetan meadow ecosystem to measure diurnal cycles of L-band TB. The daily measurements include elevation scanning sequences toward the ground and zenith (sky) measurements. The angular range considered for the elevation scans is performed every 30 min between 40°-70° (relative to nadir) in steps of 5°. The sky measurement is performed at 23:55 every day with an observation angle of 155°. Supporting micro-meteorological (e.g. solar radiation, air temperature and humidity) as well as soil moisture and temperature profile measurements are also conducted near the radiometer. Analyses of the measurements reveal that the impact on TB caused by diurnal changes of ground permittivity is generally stronger than the effect of changing ground temperature. Moreover, the simulations performed with the integrated Tor Vergata model and Noah land surface model indicate that the TB signatures of diurnal soil freeze-thaw cycle is most sensitive to the liquid water content of the soil surface layer, and the measurements taken at 5 cm depth are less representative for the L-band emission.

  3. Freeze-thaw treatment effects on the dynamic mechanical properties of articular cartilage

    Directory of Open Access Journals (Sweden)

    Muldrew Ken

    2010-10-01

    Full Text Available Abstract Background As a relatively non-regenerative tissue, articular cartilage has been targeted for cryopreservation as a method of mitigating a lack of donor tissue availability for transplant surgeries. In addition, subzero storage of articular cartilage has long been used in biomedical studies using various storage temperatures. The current investigation studies the potential for freeze-thaw to affect the mechanical properties of articular cartilage through direct comparison of various subzero storage temperatures. Methods Both subzero storage temperature as well as freezing rate were compared using control samples (4°C and samples stored at either -20°C or -80°C as well as samples first snap frozen in liquid nitrogen (-196°C prior to storage at -80°C. All samples were thawed at 37.5°C to testing temperature (22°C. Complex stiffness and hysteresis characterized load resistance and damping properties using a non-destructive, low force magnitude, dynamic indentation protocol spanning a broad loading rate range to identify the dynamic viscoelastic properties of cartilage. Results Stiffness levels remained unchanged with exposure to the various subzero temperatures. Hysteresis increased in samples snap frozen at -196°C and stored at -80°C, though remained unchanged with exposure to the other storage temperatures. Conclusions Mechanical changes shown are likely due to ice lens creation, where frost heave effects may have caused collagen damage. That storage to -20°C and -80°C did not alter the mechanical properties of articular cartilage shows that when combined with a rapid thawing protocol to 37.5°C, the tissue may successfully be stored at subzero temperatures.

  4. Numerical Simulation of the Freeze-Thaw Behavior of Mortar Containing Deicing Salt Solution.

    Science.gov (United States)

    Esmaeeli, Hadi S; Farnam, Yaghoob; Bentz, Dale P; Zavattieri, Pablo D; Weiss, Jason

    2017-02-01

    This paper presents a one-dimensional finite difference model that is developed to describe the freeze-thaw behavior of an air-entrained mortar containing deicing salt solution. A phenomenological model is used to predict the temperature and the heat flow for mortar specimens during cooling and heating. Phase transformations associated with the freezing/melting of water/ice or transition of the eutectic solution from liquid to solid are included in this phenomenological model. The lever rule is used to calculate the quantity of solution that undergoes the phase transformation, thereby simulating the energy released/absorbed during phase transformation. Undercooling and pore size effects are considered in the numerical model. To investigate the effect of pore size distribution, this distribution is considered using the Gibbs-Thomson equation in a saturated mortar specimen. For an air-entrained mortar, the impact of considering pore size (and curvature) on freezing was relatively insignificant; however the impact of pore size is much more significant during melting. The fluid inside pores smaller than 5 nm (i.e., gel pores) has a relatively small contribution in the macroscopic freeze-thaw behavior of mortar specimens within the temperature range used in this study (i.e., +24 °C to -35 °C), and can therefore be neglected for the macroscopic freeze-thaw simulations. A heat sink term is utilized to simulate the heat dissipation during phase transformations. Data from experiments performed using a low-temperature longitudinal guarded comparative calorimeter (LGCC) on mortar specimens fully saturated with various concentration NaCl solutions or partially saturated with water is compared to the numerical results and a promising agreement is generally obtained.

  5. An estimated cost of lost climate regulation services caused by thawing of the Arctic cryosphere.

    Science.gov (United States)

    Euskirchen, Eugénie S; Goodstein, Eban S; Huntington, Henry P

    2013-12-01

    Recent and expected changes in Arctic sea ice cover, snow cover, and methane emissions from permafrost thaw are likely to result in large positive feedbacks to climate warming. There is little recognition of the significant loss in economic value that the disappearance of Arctic sea ice, snow, and permafrost will impose on humans. Here, we examine how sea ice and snow cover, as well as methane emissions due to changes in permafrost, may potentially change in the future, to year 2100, and how these changes may feed back to influence the climate. Between 2010 and 2100, the annual costs from the extra warming due to a decline in albedo related to losses of sea ice and snow, plus each year's methane emissions, cumulate to a present value cost to society ranging from US$7.5 trillion to US$91.3 trillion. The estimated range reflects uncertainty associated with (1) the extent of warming-driven positive climate feedbacks from the thawing cryosphere and (2) the expected economic damages per metric ton of CO2 equivalents that will be imposed by added warming, which depend, especially, on the choice of discount rate. The economic uncertainty is much larger than the uncertainty in possible future feedback effects. Nonetheless, the frozen Arctic provides immense services to all nations by cooling the earth's temperature: the cryosphere is an air conditioner for the planet. As the Arctic thaws, this critical, climate-stabilizing ecosystem service is being lost. This paper provides a first attempt to monetize the cost of some of those lost services.

  6. Effects of glycerol concentration on the motility of equine spermatozoa after thawing

    Directory of Open Access Journals (Sweden)

    Miroslava Mráčková

    2017-01-01

    Full Text Available The aim of this study was to evaluate the effect of different glycerol concentrations on stallion sperm motility after thawing. For statistical analysis 228 ejaculates were used. The semen was filtrated to remove gel fraction; macroscopic and microscopic evaluation was done. After evaluation the ejaculates were centrifuged, the supernatant was removed and the spermatozoa were re-suspended in French diluent with different concentrations of glycerol (2.0; 2.5; 4.0 and 6.0%. The choice of concentration of glycerol for a particular ejaculate was completely random. The spermatozoa were packed into 0.5 ml straws and placed for 2 h in a fridge (4 °C. Then the straws were placed in liquid nitrogen vapor (-80 to -100 °C and after 10 min plunged into liquid nitrogen and stored at -196 °C for at least 48 h. The selected straws were individually thawed in a 38 °C water bath for 30 s prior to post-freezing analysis. Two progressive motilities using phase contrast microscopy (magnification × 400 were recorded: motility II immediately after thawing and motility III after 2 h incubation in a 38 °C water bath. The Spearmen/Kendall rang correlation test was selected to prove whether there is a correlation between the selected indices (glycerol concentration and motility II and motility III. Nonparametric multiple group analysis (Steel-Dwass test was applied for finding the differences between groups. The Spearman/Kendall rang correlation proved a relationship between motility II and glycerol concentration. It can be stated that in this study the best glycerol concentration for freezing equine spermatozoa is with a concentration of 4.0% glycerol.

  7. Regional atmospheric cooling and wetting effect of permafrost thaw-induced boreal forest loss.

    Science.gov (United States)

    Helbig, Manuel; Wischnewski, Karoline; Kljun, Natascha; Chasmer, Laura E; Quinton, William L; Detto, Matteo; Sonnentag, Oliver

    2016-12-01

    In the sporadic permafrost zone of North America, thaw-induced boreal forest loss is leading to permafrost-free wetland expansion. These land cover changes alter landscape-scale surface properties with potentially large, however, still unknown impacts on regional climates. In this study, we combine nested eddy covariance flux tower measurements with satellite remote sensing to characterize the impacts of boreal forest loss on albedo, eco-physiological and aerodynamic surface properties, and turbulent energy fluxes of a lowland boreal forest region in the Northwest Territories, Canada. Planetary boundary layer modelling is used to estimate the potential forest loss impact on regional air temperature and atmospheric moisture. We show that thaw-induced conversion of forests to wetlands increases albedo: and bulk surface conductance for water vapour and decreases aerodynamic surface temperature. At the same time, heat transfer efficiency is reduced. These shifts in land surface properties increase latent at the expense of sensible heat fluxes, thus, drastically reducing Bowen ratios. Due to the lower albedo of forests and their masking effect of highly reflective snow, available energy is lower in wetlands, especially in late winter. Modelling results demonstrate that a conversion of a present-day boreal forest-wetland to a hypothetical homogeneous wetland landscape could induce a near-surface cooling effect on regional air temperatures of up to 3-4 °C in late winter and 1-2 °C in summer. An atmospheric wetting effect in summer is indicated by a maximum increase in water vapour mixing ratios of 2 mmol mol-1 . At the same time, maximum boundary layer heights are reduced by about a third of the original height. In fall, simulated air temperature and atmospheric moisture between the two scenarios do not differ. Therefore, permafrost thaw-induced boreal forest loss may modify regional precipitation patterns and slow down regional warming trends. © 2016 John Wiley

  8. Histology as a valid and reliable tool to differentiate fresh from frozen-thawed fish.

    Science.gov (United States)

    Bozzetta, E; Pezzolato, M; Cencetti, E; Varello, K; Abramo, F; Mutinelli, F; Ingravalle, F; Teneggi, E

    2012-08-01

    Selling fish products as fresh when they have actually been frozen and thawed is a common fraudulent practice in seafood retailing. Unlike fish products frozen to protect them against degenerative changes during transportation and to extend the product's storage life, fish intended for raw consumption in European countries must be previously frozen at -20° C for at least 24 h to kill parasites. The aim of this study was to use histological analysis to distinguish between fresh and frozen-thawed fish and to evaluate this method for use as a routine screening technique in compliance with the requirements of European Commission Regulation No. 882/2004 on official food and feed controls. Method performance (i.e., accuracy and precision) was evaluated on tissue samples from three common Mediterranean fish species; the evaluation was subsequently extended to include samples from 35 fish species in a second experiment to test for method robustness. Method accuracy was tested by comparing histological results against a "gold standard" obtained from the analysis of frozen and unfrozen fish samples prepared for the study. Method precision was evaluated according to interrater agreement (i.e., three laboratories with expertise in histopathology in the first experiment and three expert analysts in the second experiment) by estimating Cohen's kappa (and corresponding 95 % confidence intervals) for each pair of laboratories and experts and the combined Cohen's kappa for all three experts and laboratories. The observed interrater agreement among the three laboratories and the three experts indicated high levels of method accuracy and precision (high sensitivity and specificity) and method reproducibility. Our results suggest that histology is a rapid, simple, and highly accurate method for distinguishing between fresh and frozen-thawed fish, regardless of the fish species analyzed.

  9. Effects of Enhanced Thaw Depth on the Composition of Arctic Soil Organic Matter Leachate

    Science.gov (United States)

    Hutchings, J.; Zhang, X.; Bianchi, T. S.; Schuur, E.; Arellano, A. R.; Liu, Y.

    2016-12-01

    Pan-Arctic permafrost is increasingly susceptible to thaw due to the disproportionally high rate of temperature change in high latitudes. These soils contain a globally significant quantity of organic carbon that, when thawed, interacts with the modern carbon cycle. Current research has focused on atmospheric carbon fluxes and transport by rivers and streams to continental shelves, but has overlooked the lateral flux of carbon within watershed soils, which is the primary link between terrestrial and riverine ecosystems. Understanding the effects of water movement through permafrost soils on dissolved organic carbon is critical to better modelling of lateral carbon fluxes and interpreting the resulting observed riverine carbon fluxes with applications to investigations of the past, present, and future of the pan-Arctic. We conducted a laboratory leaching experiment using active layer soils from the Eight Mile Lake region of interior Alaska. Cores were sampled into surface and deep sections. Surface sections were subjected to a three-stage leaching process using artificial rain, with cores stored frozen overnight between stages (which crudely simulated freeze-thaw mechanisms). Surface leachates were sampled for analysis and the remainder percolated through deep soils using the same three-staged approach. Measurements of surface and deep leachates were selected to characterize transport-related changes to dissolved organic matter and included dissolved organic carbon, fluorescent dissolved organic matter via excitation emission matrices, and molecular composition via Fourier transform ion cyclotron resonance mass spectrometry. Primary findings from the experiment include a net retention of 2.4 to 27% of dissolved organic carbon from surface leachates in deep soils, a net release of fluorescent dissolved organic matter from deep soils that was 43 to 106% greater than surface leachates, increased hydrophobicity during stage three of leaching, and the preferential

  10. Concrete Durability in Harsh Environmental Conditions Exposed to Freeze Thaw Cycles

    Science.gov (United States)

    Hamze, Youssef

    Under line Pathology of Materials; one of the environmental causes of damage effects on concrete is freeze thaw cycles, which deteriorate the concrete exposed to water in cold weather. An example of old concrete is a dam project that was built in Canada, in the early 1909-1913. This project was reconstructed in 1932, 1934 and 1972, and required renovation due to the ice abrasion with the freeze/thaw cycles. Before completing any renovation, it is required to analyze the structural stability and the concrete failures of this dam. An investigation was conducted to determine the quality of the concrete in the Piers and in the Bridge Deck Slab. It was also required to determine the basic materials' properties that constitute this project. This will improve the analysis of its stability [10]. Core samples were examined and used as test samples, for the Alkali-Silica reactivity test samples, as well as the compressive strength test, the Chloride Ion test, and the freeze thaw testing which was performed on two sets of 12 concrete core samples that were taken from different locations in the project. These locations are the representations of the age of the concrete. Thus, the age difference between the samples' two sets is four decades. Testing was performed on prisms cut from cores. ASTM C-666 procedure (A) was applied using an automatic test system [6]. It was suggested that a plan for renovation of this project should be performed after the analysis is undertaken to assess the conditions estimating the remaining life of the concrete in this project [15].

  11. Monitoring rock freezing and thawing by novel geoelectrical and acoustic techniques

    Science.gov (United States)

    Murton, Julian B.; Kuras, Oliver; Krautblatter, Michael; Cane, Tim; Tschofen, Dominique; Uhlemann, Sebastian; Schober, Sandra; Watson, Phil

    2016-12-01

    Automated monitoring of freeze-thaw cycles and fracture propagation in mountain rockwalls is needed to provide early warning about rockfall hazards. Conventional geoelectrical methods such as electrical resistivity tomography (ERT) are limited by large and variable ohmic contact resistances, requiring galvanic coupling with metal electrodes inserted into holes drilled into rock, and which can be loosened by rock weathering. We report a novel experimental methodology that combined capacitive resistivity imaging (CRI), ERT, and microseismic event recording to monitor freeze-thaw of six blocks of hard and soft limestones under conditions simulating an active layer above permafrost and seasonally frozen rock in a nonpermafrost environment. Our results demonstrate that the CRI method is highly sensitive to freeze-thaw processes; it yields property information equivalent to that obtained with conventional ERT and offers a viable route for nongalvanic long-term geoelectrical monitoring, extending the benefits of the methodology to soft/hard rock environments. Contact impedances achieved with CRI are less affected by seasonal temperature changes, the aggregate state of the pore water (liquid or frozen), and the presence of low-porosity rock with high matrix resistivities than those achieved with ERT. Microseismic monitoring has the advantage over acoustic emissions that events were recorded in relevant field distances of meters to decameters from cracking events. For the first time we recorded about 1000 microcracking events and clustered them in four groups according to frequency and waveform. Compared to previous studies, mainly on ice-cracking in glaciers, the groups are attributed to single- or multiple-stage cracking events such as crack coalescence.

  12. Response of tundra plants to environmental variation during seven years of experimentally-induced permafrost thaw

    Science.gov (United States)

    Salmon, V. G.; Schuur, E.

    2016-12-01

    Seven years of warming at the Carbon in Permafrost Experimental Heating Research Project (CiPEHR) has induced dramatic environmental changes at this tussock tundra site. By 2015, soil-warmed plots thawed 35 cm more than controls and had significantly higher surface soil moisture during the growing season. Air warming using open top chambers significantly increased growing season air temperatures by 0.35°C. We examined 7 years of species-level leaf chemistry and total aboveground biomass in order to characterize the response of tundra plant species to varying environmental conditions. For this analysis, we used a multivariate framework that spanned treatments, combining principle component analysis of environmental covariates with linear mixed effect models. Overall, warm deep soils were associated with increased total aboveground biomass as well as increased inputs of litter N to surface soils. Both of these patterns were primarily driven by the tussock-forming sedge Eriophorum vaginatum. This species exhibited increased aboveground biomass and reduced nutrient resorption efficiency with permafrost thaw. Warm air temperatures at CiPEHR also increased total aboveground biomass but did not increase vascular foliar N pools or deciduous litter N pools, indicating little effect on plant-available N. Warm air temperatures may have exacerbated competition between vascular plant species, however. Leaf %N of E. vaginatum increased while Carex bigeloweii, Rubus chamaemorus, and Vaccinium uliginosum all exhibited decreased leaf %N. Warm and dry surface soil conditions were associated with decreased total aboveground biomass, vascular foliar N pools, and deciduous litter N pools. This negative relationship suggests that moisture limitation of decomposition can reduce plant-available N at this site. We found support for the theory that permafrost thaw alleviates N limitation of tundra plants but we emphasize the important roles that soil moisture, air temperature, and species

  13. 14-Day thawed plasma retains clot enhancing properties and inhibits tPA-induced fibrinolysis.

    Science.gov (United States)

    Huebner, Benjamin R; Moore, Ernest E; Moore, Hunter B; Shepherd-Singh, Raymond; Sauaia, Angela; Stettler, Gregory R; Nunns, Geoffrey R; Silliman, Christopher C

    2017-11-01

    Plasma-first resuscitation attenuates trauma-induced coagulopathy (TIC); however, the logistics of plasma-first resuscitation require thawed plasma (TP) be readily available due to the obligatory thawing time of fresh frozen plasma (FFP). The current standard is storage of TP for up to 5 days at 4°C, based on factor levels at outdate, for use in patients at risk for TIC, but there remains a 2.2% outdated wastage rate. However, the multitude of plasma proteins in attenuating TIC remains unknown. We hypothesize that TP retains the ability to enhance clotting and reduce tPA-induced fibrinolysis at 14-day storage. FFP was thawed and stored at 4°C at the following intervals: 14, 10, 7, 5, 3, and 1-day prior to the experiment. Healthy volunteers underwent blood draws followed by 50% dilution with TP stored at previously mentioned intervals as well as FFP, normal saline (NS), albumin, and whole blood (WB) control. Samples underwent tPA-modified (75 ng/mL) thrombelastography (TEG) with analysis of R-time, angle, maximum amplitude (MA), and LY30. TEG properties did not change significantly over the thawed storage. 14-day TP retained the ability to inhibit tPA-induced hyperfibrinolysis (median LY30% 9.6%) similar to FFP (5.6%), WB (14.6%), and superior to albumin (59.3%) and NS (58.1%). 14-day TP also retained faster clot formation (median angle, 66.2°) and superior clot strength (MA, 61.5 mm) to albumin (34.8°, 21.6 mm) and NS (41.6°, 32.2 mm). TP plasma stored for 14 days retains clot-enhancing ability and resistance to clot degradation similar to FFP. A clinical trial is needed to validate these in vitro results. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Permafrost thawing in organic Arctic soils accelerated by ground heat production

    DEFF Research Database (Denmark)

    Hollesen, Jørgen; Matthiesen, Henning; Møller, Anders Bjørn

    2015-01-01

    recognized as a potential positive-feedback mechanism that would enhance permafrost thawing and the release of carbon3, 4. This internal heat production is poorly understood, however, and the strength of this effect remains unclear3. Here, we have quantified the variability of heat production in contrasting...... organic permafrost soils across Greenland and tested the hypothesis that these soils produce enough heat to reach a tipping point after which internal heat production can accelerate the decomposition processes. Results show that the impact of climate changes on natural organic soils can be accelerated...

  15. Ovarian hyperstimulation syndrome and prophylactic human embryo cryopreservation: analysis of reproductive outcome following thawed embryo transfer

    Directory of Open Access Journals (Sweden)

    Sills Eric

    2008-11-01

    Full Text Available Abstract Objective To review utilisation of elective embryo cryopreservation in the expectant management of patients at risk for developing ovarian hyperstimulation syndrome (OHSS, and report on reproductive outcome following transfer of thawed embryos. Materials and methods Medical records were reviewed for patients undergoing IVF from 2000–2008 to identify cases at risk for OHSS where cryopreservation was electively performed on all embryos at the 2 pn stage. Patient age, total number of oocytes retrieved, number of 2 pn embryos cryopreserved, interval between retrieval and thaw/transfer, number (and developmental stage of embryos transferred (ET, and delivery rate after IVF were recorded for all patients. Results From a total of 2892 IVF cycles undertaken during the study period, 51 IVF cases (1.8% were noted where follicle number exceeded 20 and pelvic fluid collection was present. Elective embryo freeze was performed as OHSS prophylaxis in each instance. Mean (± SD age of these patients was 32 ± 3.8 yrs. Average number of oocytes retrieved in this group was 23 ± 8.7, which after fertilisation yielded an average of 14 ± 5.7 embryos cryopreserved per patient. Thaw and ET was performed an average of 115 ± 65 d (range 30–377 d after oocyte retrieval with a mean of 2 ± 0.6 embryos transferred. Grow-out to blastocyst stage was achieved in 88.2% of cases. Delivery/livebirth rate was 33.3% per initiated cycle and 43.6% per transfer. Non-transferred blastocysts remained in cryostorage for 24 of 51 patients (46.1% after ET, with an average of 3 ± 3 blastocysts refrozen per patient. Conclusion OHSS prophylaxis was used in 1.8% of IVF cycles at this institution; no serious OHSS complications were encountered during the study period. Management based on elective 2 pn embryo cryopreservation with subsequent thaw and grow-out to blastocyst stage for transfer did not appear to compromise embryo viability or overall reproductive outcome. For

  16. RELATIONSHIP BETWEEN MOTILITY AND VIABILITY PARAMETERS OF FROZEN-THAWED BULL SPERMATOZOA

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    Eliška Špaleková

    2013-02-01

    Full Text Available The aim of this study was to determine relationship between parameters of spermatozoa motility (total motility - TM and progressive movement - PM and viability of bull frozen-thawed spermatozoa (dead spermatozoa ratio, apoptotic spermatozoa ratio and plasma membrane integrity. Motility parameters were evaluated using computer-assisted semen analysis (CASA. Parameters of spermatozoa viability were analysed using fluorescent dyes PNA-FITC (plasma membrane, Yo-Pro-1 and propidium iodide (PI. All bulls (n=6 were divided into two groups. First group (n=3 A – better bulls with total motility after thawing over 40% and the second group (n=3 B – with total motility lower than 40%. It was observed significantly (P<0.001 higher TM and PM in group A. No significant differences in velocity parameters and ALH between the group A and B were detected. Occurrence of spermatozoa with disrupted membranes, dead/necrotic spermatozoa and apoptotic spermatozoa was significantly lower in the group A. Bulls in the group A showed significantly higher cleavage rate of embryos. These motility and viability characteristics are associated with a higher embryo cleavage rate in in vitro fertilizatioThe aim of this study was to determine relationship between parameters of spermatozoa motility (total motility - TM and progressive movement - PM and viability of bull frozen-thawed spermatozoa (dead spermatozoa ratio, apoptotic spermatozoa ratio and plasma membrane integrity. Motility parameters were evaluated using computer-assisted semen analysis (CASA. Parameters of spermatozoa viability were analysed using fluorescent dyes PNA-FITC (plasma membrane, Yo-Pro-1 and propidium iodide (PI. All bulls (n=6 were divided into two groups. First group (n=3 A – better bulls with total motility after thawing over 40% and the second group (n=3 B – with total motility lower than 40%. It was observed significantly (P<0.001 higher TM and PM in group A. No significant differences in

  17. Permafrost thaw and destabilization of Alpine rock walls in the hot summer of 2003

    Science.gov (United States)

    Gruber, Stephan; Hoelzle, Martin; Haeberli, Wilfried

    2004-07-01

    Exceptional rockfall occurred throughout the Alps during the unusually hot summer of 2003. It is likely related to the fast thermal reaction of the subsurface of steep rock slopes and a corresponding destabilization of ice-filled discontinuities. This suggests that rockfall may be a direct and unexpectedly fast impact of climate change. Based upon our measurements in Alpine rock faces, we present model simulations illustrating the distribution and degradation of permafrost where the summer of 2003 has resulted in extreme thaw. We argue that hotter summers predicted by climate models for the coming decades will result in reduced stability of many alpine rock walls.

  18. Effects of Domestic Storage and Thawing Practices on Salmonella in Poultry-Based Meat Preparations.

    Science.gov (United States)

    Roccato, Anna; Uyttendaele, Mieke; Cibin, Veronica; Barrucci, Federica; Cappa, Veronica; Zavagnin, Paola; Longo, Alessandra; Catellani, Paolo; Ricci, Antonia

    2015-12-01

    Among consumer food handling practices, time-temperature abuse has been reported as one of the most common contributory factors in salmonellosis outbreaks where the evidence is strong. The present study performed storage tests of burgers, sausages, and kebabs and investigated (i) the effect of refrigerator temperatures (4°C versus 8 or 12°C, which were the temperatures recorded in 33 and 3%, respectively, of domestic refrigerators in Italy), with or without prior temperature abuse (25°C for 2 h, simulating transport of meats from shop to home), and (ii) the impact of the thawing method (overnight in the refrigerator at 8°C versus on the kitchen countertop at 23°C) on the presence and numbers of Salmonella bacteria. Storage tests were carried out on naturally or artificially (Salmonella enterica serovar Typhimurium at ca. 10 CFU/g) contaminated products, while freezing-thawing tests were conducted only on artificially contaminated products (Salmonella Typhimurium at ca. 10, 100, and 1,000 CFU/g). The results from the artificially contaminated products showed significant (P 710 MPN/g) in kebabs after 7 and 10 days but more moderate growth in sausages (i.e., from ca. 14 MPN/g to a maximum of 96 MPN/g after 9 days of storage). Storage of naturally contaminated burgers or sausages (contamination at or below 1 MPN/g) at 4, 8, or 12°C and a short time of temperature abuse (2 h at 25°C) did not facilitate an increase in the presence and numbers of Salmonella bacteria. Thawing overnight in the refrigerator led to either a moderate reduction or no change of Salmonella Typhimurium numbers in burgers, sausages, and kebabs. Overall, this study showed that domestic storage and thawing practices can affect food safety and that time-temperature abuse can cause a substantial increase of Salmonella numbers in some types of poultry-based meat preparations, highlighting that efforts for the dissemination of consumer guidelines on the correct storage and handling of meats need

  19. The influence of the curing conditions of concrete on durability after freeze-thaw accelerated testing

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    Al-Assadi, G.

    2015-12-01

    Full Text Available This work relates the curing conditions of concrete with the damage caused by rapid freeze-thaw cycles (ASTM C 666. The “potential” durability of concrete after testing is also studied. In countries with a continental climate, the curing of concrete in summer is performed under high-temperature and low-humidity conditions, and during the winter the concrete undergoes freezing and thawing. This paper shows the experimental results of the behaviour of concrete specimens cured under climatic summer conditions and then subjected to freeze-thaw cycles. Curing of the specimens includes conditions of good and bad practice in relation to wetting and protection of the concrete. Mechanical properties, cement hydration, volume and pore sizes, oxygen permeability, chloride diffusion and water penetration under pressure tests of the concrete are assessed. These tests were performed before and after the application of the freeze-thaw cycles. Statistical analysis of the correlation among variables is also included.Este trabajo relaciona las condiciones de curado del hormigón con los daños causados por ciclos hielo-deshielo (ASTM C 666. Estudia la durabilidad “potencial” del hormigón dañado por este ensayo. En países con clima continental, el curado del hormigón en verano se realiza con alta temperatura y baja humedad, y durante el invierno sufre condiciones de hielo-deshielo. Se presentan los resultados experimentales de probetas de hormigón curadas bajo condiciones climáticas del verano y luego sometidas a ciclos hielo-deshielo. El curado de las probetas incluye condiciones de buenas y malas prácticas en relación con el curado del hormigón. Se miden las propiedades mecánicas, grado de hidratación, volumen de poros y distribución de tamaños, permeabilidad al oxígeno, penetración de agua bajo presión y coeficiente de difusión de cloruros antes y después de la aplicación de los ciclos de hielo-deshielo. Se incluye un estudio estad

  20. [Effects and mechanism of freeze-thawing cycles on key processes of nitrogen cycle in terrestrial ecosystem].

    Science.gov (United States)

    Wang, Li-qin; Qi, Yu-chun; Dong, Yun-she; Peng, Qin; Guo, Shu-fang; He, Yun-long; Yan, Zhong-qing

    2015-11-01

    As a widespread natural phenomenon in the soil of middle and high latitude as well as high altitude, freeze-thawing cycles have a great influence on the nitrogen cycle of terrestrial ecosystem in non-growing season. Freeze-thawing cycles can alter the physicochemical and biological properties of the soil, which thereby affect the migration and transformation of soil nitrogen. The impacts of freeze-thawing cycles on key processes of nitrogen cycle in terrestrial ecosystem found in available studies remain inconsistent, the mechanism is still not clear, and the research methods also need to be further explored and innovated. So it is necessary to sum up and analyze the existing achievements in order to better understand the processes of soil nitrogen cycle subjected to freeze-thawing cycles. This paper reviewed the research progress in China and abroad about the effects and mechanisms of freeze-thawing cycles on key processes of nitrogen cycle in terrestrial ecosystem, including mineralization, immobilization, nitrification and denitrification, N leakage and gaseous loss, and analyzed the deficiencies of extant research. The possible key research topics that should be urgently paid more attention to in the future were also discussed.

  1. Improving CLM4.5 simulations of land-atmosphere exchange during freeze-thaw processes on the Tibetan Plateau

    Science.gov (United States)

    Luo, Siqiong; Fang, Xuewei; Lyu, Shihua; Zhang, Yu; Chen, Boli

    2017-10-01

    Soil is heterogeneous and has different thermal and hydraulic properties, causing varied behavior in heat and moisture transport. Therefore, soil has an important effect on land-atmosphere interactions. In this study, an improved soil parameterization scheme that considers gravel and organic matter in the soil was introduced into CLM4.5 (Community Land Model). By using data from the Zoige and Madoi sites on the Tibetan Plateau, the ability of the model to simultaneously simulate the duration of freeze-thaw periods, soil temperature, soil moisture, and surface energy during freeze-thaw processes, was validated. The results indicated that: (1) the new parameterization performed better in simulating the duration of the frozen, thawing, unfrozen, and freezing periods; (2) with the new scheme, the soil thermal conductivity values were decreased; (3) the new parameterization improved soil temperature simulation and effectively decreased cold biases; (4) the new parameterization scheme effectively decreased the dry biases of soil liquid water content during the freezing, completely frozen, and thawing periods, but increased the wet biases during the completely thawed period; and (5) the net radiation, latent heat flux, and soil surface heat flux of the Zoige and Madoi sites were much improved by the new organic matter and thermal conductivity parameterization.

  2. Combinations of glycerol percent, glycerol equilibration time, and thawing rate upon freezability of bull spermatozoa in plastic straws.

    Science.gov (United States)

    Wiggin, H B; Almquist, J O

    1975-03-01

    Twelve ejaculates were used in a central composite experiment to test 15 combinations of glycerol (7, 9, 11, 13, or 15%), glycerol equilibration times (1, 2, 4, 8, or 16 h) and thawing rates (water at 35 C for 15 s, 50 C for 13 s, 65 C for 11 s, 80 C for 9 s, or 95 C for 7 s). Semen was diluted in heated skim milk-glycerol, packaged in .3-ml. Continental U.S. straws and frozen in liquid nitrogen vapor. Based on post-thaw progressive sperm motility after storage at -196 C for 9 to 11 days, estimated optima from multiple regression were 10.7% for glycerol, 2.0 h for glycerol equilibration time, and 76 C for thawing bath temperature. Only the linear effect for each variable was significant. Much faster thawing rates and shorter glycerol equilibration times than those for freezing bull spermatozoa in glass ampules should be used for maximum post-thaw sperm motility in straws.

  3. INFLUENCE OF CYCLIC FREEZING AND THAWING ON THE HYDRAULIC CONDUCTIVITY OF SELECTED AGGREGATES USED IN THE CONSTRUCTION OF GREEN ROOFS

    Directory of Open Access Journals (Sweden)

    Karolina Gwóżdź

    2016-09-01

    Full Text Available The construction of a green roof requires drainage which ought to be characterized by adequate hydraulic conductivity and be resistant to changing meteorological conditions during the winter period. A properly functioning drainage system guarantees the reliability of the entire green roof system. The article presents studies on the freeze-thaw durability and hydraulic conductivity of selected aggregates applied for constructing green roof drainage systems. The aggregates were subjected to a cyclic freezing and thawing process in 30 and 70 cycles. The obtained results indicate that the conductivity of aggregates studied using the constant head method decreases along with an increase in the number of freeze-thaw cycles they were subjected to. This means that the indicator of freeze-thaw durability can have an indicative nature in the assessment of the usefulness of selected aggregates for constructing drainage layers. The conducted studies indicate that the deciding parameter when selecting an aggregate ought to be its hydraulic conductivity, determined accounting for the changes taking place in the freeze-thaw cycles. The equations of changes in the conductivity of aggregates indicated by the authors make it possible to assess them for practical purposes.

  4. Effect of thawing and cold storage on frozen chicken thigh meat quality by high-voltage electrostatic field.

    Science.gov (United States)

    Hsieh, Chang-Wei; Lai, Cheng-Hung; Ho, Wai-Jane; Huang, Su-Chen; Ko, Wen-Ching

    2010-05-01

    One of the most popular issues in electrostatic biology is the effects of a high-voltage electrostatic field (HVEF) on the thawing of chicken thigh meat. In this study, chicken thigh meat was treated with HVEF (E-group), and compared to samples stored in a common refrigerator (R-group), to investigate how HVEF affects chicken thigh meat quality after thawing at low temperature storage (-3 and 4 degrees C). The results showed that there were no significant differences in biochemical and microorganism indices at -3 degrees C. However, the HVEF can significantly shorten thawing time for frozen chicken thigh meat at -3 degrees C. After thawing chicken thigh meat and storing at 4 degrees C, the total viable counts reached the Intl. Commission on Microbiological Specification for Foods limit of 10(7) CFU/g on the 6 and 8 d for the R- and E-group, respectively. On the 8th d, the volatile basic nitrogen had increased from 11.24 mg/100 g to 21.9 mg/100 g for the E-group and 39.9 mg/100 g for the R-group, respectively. The biochemical and microorganism indices also indicated that the E-group treatment yielded better results on thawing than the R-group treatment. The application of this model has the potential to keep products fresh.

  5. Optimal Thawing of Cryopreserved Peripheral Blood Mononuclear Cells for Use in High-Throughput Human Immune Monitoring Studies

    Directory of Open Access Journals (Sweden)

    Ramu A. Subbramanian

    2012-07-01

    Full Text Available Cryopreserved peripheral blood mononuclear cells (PBMC constitute an important component of immune monitoring studies as they allow for efficient batch- testing of samples as well as for the validation and extension of original studies in the future. In this study, we systematically test the permutations of PBMC thawing practices commonly employed in the field and identify conditions that are high and low risk for the viability of PBMC and their functionality in downstream ELISPOT assays. The study identifies the addition of ice-chilled washing media to thawed cells at the same temperature as being a high risk practice, as it yields significantly lower viability and functionality of recovered PBMC when compared to warming the cryovials to 37 °C and adding a warm washing medium. We found thawed PBMC in cryovials could be kept up to 30 minutes at 37 °C in the presence of DMSO before commencement of washing, which surprisingly identifies exposure to DMSO as a low risk step during the thawing process. This latter finding is of considerable practical relevance since it permits batch-thawing of PBMC in high-throughput immune monitoring environments.

  6. EFFECT OF NON-ENZYMATIC ANTIOXIDANTS IN EXTENDER ON POST-THAW QUALITY OF BUFFALO (BUBALUS BUBALIS BULL SPERMATOZOA

    Directory of Open Access Journals (Sweden)

    S. M. H. ANDRABI, M. S. ANSARI, N. ULLAH AND M. AFZAL

    2008-12-01

    Full Text Available The objective of the present study was to determine the effect of non-enzymatic antioxidants (vitamin C or E in tris-citric acid buffer (TCA on post-thaw quality of buffalo (Bubalus bubalis bull spermatozoa. Split pooled buffalo bull ejaculates were diluted in TCA egg yolk glycerol extender containing either vitamin C (TCAC, vitamin E (TCAE or without antioxidant (TCAN at 37°C. Extended semen was cooled to 4C in 2 h and equilibrated for 4 h at 4C. Cooled semen was then filled in 0.5 ml straws at 4C and frozen in programmable cell freezer. Thawing of semen was performed at 37°C for 30 seconds. Sperm motility, plasma membrane integrity and sperm morphology (acrosome integrity, head, mid-piece and tail abnormalities of each semen sample were evaluated. Percentage of post-thaw spermatozoal motility assessed visually at 0 and 6 h and the post-thaw percentage of spermatozoa with intact plasma membranes at 0 h were higher (P0.05. In conclusion, non-enzymatic antioxidants, particularly vitamin E, in the tris citric acid extender may improve the quality of frozen-thawed buffalo bull spermatozoa.

  7. Freeze-thaw immobilization of liposomes in chromatographic gel beads: evaluation by confocal microscopy and effects of freezing rate.

    Science.gov (United States)

    Lundqvist, A; Ocklind, G; Haneskog, L; Lundahl, P

    1998-01-01

    Biological membranes immobilized in chromatographic gel beads constitute a multifunctional affinity matrix. Membrane protein-solute interactions and drug partitioning into the lipid bilayers can conveniently be studied. By the use of confocal laser-scanning microscopy (CLSM) the distribution of immobilized model membranes in the beads has been visualized for the first time. Freeze-thaw-immobilized liposomes in Superdex 200 gel beads were situated in a thick shell surrounding a liposome-free core. The amount of phospholipids immobilized by freeze-thawing was dependent on the temperature in the cooling bath and the type of test tube used. A bath temperature of -25 degrees C gave higher immobilization yield than freezing at -75 or -8 degrees C did. Freeze-thawing in the presence of liposomes did not affect the gel bead shape or the refractive index homogeneity of the agarose network of the beads, as shown by confocal microscopy.

  8. Enhancing the Properties of Conductive Polymer Hydrogels by Freeze-Thaw Cycles for High-Performance Flexible Supercapacitors.

    Science.gov (United States)

    Li, Wanwan; Lu, Han; Zhang, Ning; Ma, Mingming

    2017-06-14

    We report that a postsynthesis physical process (freeze-thaw cycles) can reform the microstructure of conductive polymer hydrogels from clustered nanoparticles to interconnected nanosheets, leading to enhanced mechanical and electrochemical properties. The polyaniline-poly(vinyl alcohol) hydrogel after five freeze-thaw cycles (PPH-5) showed remarkable tensile strength (16.3 MPa), large elongation at break (407%), and high electrochemical capacitance (1053 F·g-1). The flexible supercapacitor based on PPH-5 provided a large capacitance (420 mF·cm-2 and 210 F·g-1) and high energy density (18.7 W·h·kg-1), whose robustness was demonstrated by its 100% capacitance retention after 1000 galvanostatic charge-discharge cycles or after 1000 mechanical folding cycles. The outstanding performance enables PPH-5 based supercapacitor as a promising power device for flexible electronics, which also demonstrates the merit of freeze-thaw cycles for enhancing the performance of functional hydrogels.

  9. Study on the Freeze-Thaw Performance of Concrete Using Granulated Blast-Furnace Slag as Fine Aggregate

    Directory of Open Access Journals (Sweden)

    Liu Qiang

    2016-01-01

    Full Text Available In this paper, the freeze-thaw performance of concrete using granulated blast-furnace slag (GBS as fine aggregate was studied. According to the test method for slow freezing and thawing, degradation of mechanical properties about GBS concrete with 2 kinds W/B ratio and 3 kinds GBS replacement ratio were tested, and micromorphology of GBS concrete were analyzed by scanning electron microscopy (SEM. Furthermore, relations between degradation of mechanical properties and micromorphology about GBS concrete are discussed. Test results show that: after freeze-thaw cycles, the relative compressive strength of GBS concrete is greater than ordinary river sand concrete, and the GBS concrete will produce more mutual interlacing fibrous and flowers from crystal, the growth of these crystals can improve the compressive strength of concrete. Therefore, the frost resistance of GBS concrete is little better than ordinary river sand concrete.

  10. Changes of Soil Aggregate Stability as a Result of the Effect of Freeze-thaw Cycles

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    Aneta Žabenská

    2015-01-01

    Full Text Available The objective of the present research was to assess the changes in soil erodibility during the non-vegetation period as one of the factors affecting the snowmelt erosion. The temperature fluctuation was simulated with the use of a climatic chamber ex situ. The soil surface was for simplicity reasons considered without any plant or snow cover. The paper deals with the rate of soil erodibility determination – the soil erodibility should increase due to the decrease of soil aggregate stability depending on the number of freeze-thaw cycles and initial soil moisture. Soil samples (taken from three sites were subjected to freeze-thaw cycles under laboratory conditions. Changes in soil agreggate stability were monitored as one of the main soil characteristics which determine the soil erodibility. Two methods were used to determine the soil macroaggregate stability (soil aggregate fraction 1–2 mm: standard single-sieve method of wet sieving (Kemper and Rosenau, 1986, and dry aggregate analysis using a set of flat sieves with a diameter of 1 mm and 0.5 mm. The results of each method are controversial. Intended hypothesis has not been clearly confirmed.

  11. Cryoprotection mechanisms of polyethylene glycols on lactate dehydrogenase during freeze-thawing.

    Science.gov (United States)

    Mi, Yanli; Wood, George; Thoma, Laura

    2004-09-07

    The purpose of this study was to explore the cryoprotection mechanisms of high molecular weight polyethylene glycols (PEGs) (eg, PEG 4000 and PEG 8000) on lactate dehydrogenase (LDH). Ultraviolet activity assays, circular dichroism (CD) spectroscopy, gel filtration, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), (14)C-PEG 4000 labeling and binding, and cryostage microscopic study were conducted. Different molecular weights and concentrations of PEGs in LDH formulations were treated by freeze-thawing. Higher molecular weights and concentrations of PEGs in LDH-PEG formulations obtained better activity and secondary structure recoveries of LDH after freeze-thawing. Insoluble aggregation of LDH was not observed in gel filtration studies. SDS-PAGE results suggested surface characteristic modifications of LDH by the larger molecular weight PEGs. The 14C-PEG 4000 labeling and binding study showed extensive nonspecific interactions between the PEG 4000 and LDH molecules in a concentration-dependent manner. The bound LDH-PEG 4000/free PEG 4000 ratio increased when LDH or PEG 4000 concentrations increased. Cryostage microscopic study showed that PEG 8000 delayed the ice crystallization and eutectic transition of LDH formulation. It appeared that multiple mechanisms were at work during PEGs' cryoprotection of LDH. It was unclear whether the delayed eutectic characteristics of PEGs contributed to LDH cryoprotection. The favorable interaction, rather than preferential exclusion, between LDH and PEGs (eg, 4000) cryoprotected LDH.

  12. Platelet rich plasma associated with heterologous fresh and thawed chondrocytes on osteochondral lesions of rabbits

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    R.R. Filgueiras

    2014-02-01

    Full Text Available Chondrocytes obtained from stifle joint of New Zealand White rabbits were cultivated. Half of cells were maintained in culture for later implantation and the others frozen during six months to evaluate viability. A circular osteochondral defect was created in the right stifle of other twenty seven rabbits. The control group (CG received no treatment. The thawed (TH and fresh (FH heterologous groups received, respectively, an implant of cultivated thawed or fresh heterologous chondrocytes associated with platelet rich plasma (PRP. The CG group showed greatest pain and lameness compared to the other groups seven days after the implantation. Microscopically, at 45 and 90 days, the TH and FH groups showed filling with cartilaginous tissue containing chondrocytes surrounded by a dense matrix of glycosaminoglycans. In the CG group, healing occurred with vascularized fibrous connective tissue without integration to the subchondral bone. Cryopreserved heterologous chondrocytes were viable for implantation and healing of osteochondral lesions; the association with PRP allows the fixation of cells in the lesion and offers growth factors which accelerates repair with tissue similar to articular hyaline cartilage.

  13. Effect of the thawing time of castor bean pollen grains stored at different temperatures

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    Cristina Copstein Cuchiara

    2012-11-01

    Full Text Available This paper aimed at evaluating the effect of thawing time of pollen grains of castor bean cultivars undergoing different environmental conditions and storage periods. For this, pollen grains were maintained in four environments: refrigerator (4ºC, freezer (-18ºC, ultrafreezer (-72ºC, and liquid nitrogen (-196ºC for 60 days. To evaluate viability, in vitro germination was carried out in three tests: 15, 30, and 60 days, in which the pollens grains germinated within an hour were analyzed up to 6h and after 24h. In a completely randomized design, 100 pollen grains were analyzed in the 6 replications of each treatment. For the cultivar IAC 80, both after 15 and 30 days of storage in ultrafreezer, about 50% of pollen grains germinated required from 5h to 6h of incubation for the resumption of metabolism, respectively. For the cultivar AL Guarany 2002, ultrafreezer presented a higher degree of technical uniformity; however, the best germination was achieved through criopreservation. After 60 days, there was a dramatic decrease in the viability under all environmental conditions. Depending on the temperature, there may be a need for a larger thawing time for the resumption of physiological activities.

  14. Morphology-dependent water budgets and nutrient fluxes in arctic thaw ponds

    Science.gov (United States)

    Koch, Joshua C.; Gurney, Kirsty; Wipfli, Mark S.

    2014-01-01

    Thaw ponds on the Arctic Coastal Plain of Alaska are productive ecosystems, providing habitat and food resources for many fish and bird species. Permafrost in this region creates unique pond morphologies: deep troughs, shallow low-centred polygons (LCPs) and larger coalescent ponds. By monitoring seasonal trends in pond volume and chemistry, we evaluated whether pond morphology and size affect water temperature and desiccation, and nitrogen (N) and phosphorus (P) fluxes. Evaporation was the largest early-summer water flux in all pond types. LCPs dried quickly and displayed high early-summer nutrient concentrations and losses. Troughs consistently received solute-rich subsurface inflows, which accounted for 12 to 42 per cent of their volume and may explain higher P in the troughs. N to P ratios increased and ammonium concentrations decreased with pond volume, suggesting that P and inorganic N availability may limit ecosystem productivity in older, larger ponds. Arctic summer temperatures will likely increase in the future, which may accelerate mid-summer desiccation. Given their morphology, troughs may remain wet, become warmer and derive greater nutrient loads from their thawing banks. Overall, seasonal- to decadal-scale warming may increase ecosystem productivity in troughs relative to other Arctic Coastal Plain ponds. 

  15. Synthesis of poly(vinyl alcohol)-magnetite ferrogel obtained by freezing-thawing technique

    Science.gov (United States)

    Reséndiz-Hernández, P. J.; Rodríguez-Fernández, O. S.; García-Cerda, L. A.

    Polymer gels are crosslinked polymer networks swollen by a fluid. If magnetic particles either as powder or dispersed in a magnetic fluid are introduced into the gel then the system becomes sensitive to external magnetic fields and the resulting material is called ferrogel. The polyvinyl alcohol (PVA)-magnetite ferrogels system has properties that are attractive for artificial muscles and drug delivery systems for biomedical applications. This work investigates the synthesis and characterization of a ferrogel obtained by freezing-thawing cycles. PVA ( MW=89,000-98,000, degree of hydrolyzation: 99 mol%) and magnetite nanoparticles (˜12 nm) obtained by chemical coprecipitation were used as raw materials. The PVA-magnetite ferrogels were prepared by subjecting a PVA/DMSO/magnetite solution (2 g/30 ml/0.2 g) to freeze (-25 °C)/thaw (+25 °C) cycles. The resulting ferrogel was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), differential scanning calorimetry (DSC) and vibration sample magnetometry (VSM). The magnetic particles inside the PVA matrix formed agglomerates with average size ˜58 nm. All the ferrogels showed superparamagnetic behavior with maximum magnetization of 0.6 emu/g.

  16. Constraining Soil C Loss upon Thaw: Comparing Soils with and without Permafrost

    Science.gov (United States)

    Harden, J. W.; Ping, C. L.; O'Donnell, J. A.; Koven, C. D.; Michaelson, G. J.; Genet, H.; Xu, X.

    2014-12-01

    Permafrost thaw, with its state change and increased temperature, clearly results in increased decomposition, but constraining directions and amounts of net C exchange is confounded by feedbacks among dynamic vegetation and soil layers, nutrients, and microbial communities. One way to constrain potential loss is to compare soils with and without permafrost. We compared three sets of soil profiles developed in late Pleistocene loess from various slope positions in western Iowa (no permafrost for >10ka), south-central Alaska (no permafrost for > 3550 y), and interior Alaska (current permafrost). In Iowa C where deep C was protected by loess burial, % soil C declined most precipitously with depth (down to < 0.6 %C at 1m). Alaska soils with and without permafrost were similar in %C at 1m depths (up to 2% C). However soils with permafrost had 2X to 4X more C than non-permafrost soils at 1.5 m and maintained high and highly variable (0.8 to 11% C) C contents below 150 cm. Data provide an additional line of evidence that carbon in deep permafrost is highly susceptible to loss upon thawing. Meanwhile modeling and forecasting C fate requires more insight into C protection and stabilization by burial.

  17. Optimization of viral resuspension methods for carbon-rich soils along a permafrost thaw gradient

    Directory of Open Access Journals (Sweden)

    Gareth Trubl

    2016-05-01

    Full Text Available Permafrost stores approximately 50% of global soil carbon (C in a frozen form; it is thawing rapidly under climate change, and little is known about viral communities in these soils or their roles in C cycling. In permafrost soils, microorganisms contribute significantly to C cycling, and characterizing them has recently been shown to improve prediction of ecosystem function. In other ecosystems, viruses have broad ecosystem and community impacts ranging from host cell mortality and organic matter cycling to horizontal gene transfer and reprogramming of core microbial metabolisms. Here we developed an optimized protocol to extract viruses from three types of high organic-matter peatland soils across a permafrost thaw gradient (palsa, moss-dominated bog, and sedge-dominated fen. Three separate experiments were used to evaluate the impact of chemical buffers, physical dispersion, storage conditions, and concentration and purification methods on viral yields. The most successful protocol, amended potassium citrate buffer with bead-beating or vortexing and BSA, yielded on average as much as 2-fold more virus-like particles (VLPs g−1 of soil than other methods tested. All method combinations yielded VLPs g−1 of soil on the 108 order of magnitude across all three soil types. The different storage and concentration methods did not yield significantly more VLPs g−1 of soil among the soil types. This research provides much-needed guidelines for resuspending viruses from soils, specifically carbon-rich soils, paving the way for incorporating viruses into soil ecology studies.

  18. CHARACTERISTIC OF FROZEN-THAWED EPIDIDYMAL SPERMATOZOA AND REFRIGERATED STORAGE OF RAM SPERMATOZOA

    Directory of Open Access Journals (Sweden)

    N.W.K. Karja

    2014-10-01

    Full Text Available Post-mortem spermatozoa recovery is an important technique for obtaining germplasm reservesfrom genetically valuable animals or endangered species. The purpose of this study was to studywhether ram spermatozoa within epididymides stored at 4º C for 24 and 48 h remain their motility andviability. The characteristic of ram epididymal spermatozoa after freezing and thawing was alsoobserved. Six pairs of ram testes with attached epididymides were used in this study. The motility ofcontrol spermatozoa was well maintained throughout the dilution procedure (83.3±1.1, 80±1.3, and80±1.3% for collection, Niwa and Sasaki freezing -1 extender (NSF-1 and NSF-2 groups respectively;but declined (P<0.05 after freezing and thawing (38.3±3.1%. Motile and viable spermatozoa could berecovered from epididymides up to 48 h of storage, although their quality declined significantly(P<0.05 as post-mortem storage time increased (motility: 83±1.2, 67±3.0, and 46±5.1; viability:84.2±2.4, 73±2.8, and 66.6±2.6 % for control, 24 h and 48 h group respectively. These data indicatethat ram epididymides could be stored at 4º C for 48 h when epididymal spermatozoa cannot beimmmediately collected and cryopreserved. These storage conditions might be possible to use forepididymal sperm recovery in wild ruminants.

  19. Pengaruh Berbagai Konsentrasi Dimethylsulfoxide terhadap Kualitas Semen Beku Ayam Hutan Hijau Post Thawing

    Directory of Open Access Journals (Sweden)

    Wayan Bebas

    2015-06-01

    Full Text Available The process of freezing and thawing on semen can lead to physical stress, often called cold shock, and couses the structural and biochemical damage that affecting cell function and ultimately lead to the death of the cell The aim of this study was to know the effect of the addition of various concentrations of dimethylsulfoxide (DMSO as the intracellular cryoprotectant in phosphate yolk diluent on the post thowing quality of the green jungle fowl semen. The study used eight green jungle fowl semens which were collected with massage techniques. Semen was evaluated macroscopically and microscopically. Good quality semen was diluted with phosphate yolk which was added four different concentration of DMSO, namely 4%, 6%, 8%, and 10%. Semen was then filled and sealed in a mini straw (0.25 mL with the concentration of 150.106 cells, and equilibrated at 4oC for 4 hours. The semen freezing was processed using conventional method. Evaluation was performed on post thawing semen. The evaluation of semen quality included the progressive motility and plasma membrane intact. Data were analyzed by analysis of variance. If there were any significant differences, the data were futher analyzed by Duncan test. The results showed that addition of DMSO concentration of 6% has resulted the progressive motility and intact plasma membrane higher significantly (P <0.05 than those of the addition of DMSO concentration 4%, 8%, and 10%.

  20. Diversity and potential activity of methanotrophs in high methane-emitting permafrost thaw ponds.

    Directory of Open Access Journals (Sweden)

    Sophie Crevecoeur

    Full Text Available Lakes and ponds derived from thawing permafrost are strong emitters of carbon dioxide and methane to the atmosphere, but little is known about the methane oxidation processes in these waters. Here we investigated the distribution and potential activity of aerobic methanotrophic bacteria in thaw ponds in two types of eroding permafrost landscapes in subarctic Québec: peatlands and mineral soils. We hypothesized that methanotrophic community composition and potential activity differ regionally as a function of the landscape type and permafrost degradation stage, and locally as a function of depth-dependent oxygen conditions. Our analysis of pmoA transcripts by Illumina amplicon sequencing and quantitative PCR showed that the communities were composed of diverse and potentially active lineages. Type I methanotrophs, particularly Methylobacter, dominated all communities, however there was a clear taxonomic separation between the two landscape types, consistent with environmental control of community structure. In contrast, methanotrophic potential activity, measured by pmoA transcript concentrations, did not vary with landscape type, but correlated with conductivity, phosphorus and total suspended solids. Methanotrophic potential activity was also detected in low-oxygen bottom waters, where it was inversely correlated with methane concentrations, suggesting methane depletion by methanotrophs. Methanotrophs were present and potentially active throughout the water column regardless of oxygen concentration, and may therefore be resilient to future mixing and oxygenation regimes in the warming subarctic.

  1. Diversity and potential activity of methanotrophs in high methane-emitting permafrost thaw ponds

    Science.gov (United States)

    Vincent, Warwick F.; Comte, Jérôme; Matveev, Alex; Lovejoy, Connie

    2017-01-01

    Lakes and ponds derived from thawing permafrost are strong emitters of carbon dioxide and methane to the atmosphere, but little is known about the methane oxidation processes in these waters. Here we investigated the distribution and potential activity of aerobic methanotrophic bacteria in thaw ponds in two types of eroding permafrost landscapes in subarctic Québec: peatlands and mineral soils. We hypothesized that methanotrophic community composition and potential activity differ regionally as a function of the landscape type and permafrost degradation stage, and locally as a function of depth-dependent oxygen conditions. Our analysis of pmoA transcripts by Illumina amplicon sequencing and quantitative PCR showed that the communities were composed of diverse and potentially active lineages. Type I methanotrophs, particularly Methylobacter, dominated all communities, however there was a clear taxonomic separation between the two landscape types, consistent with environmental control of community structure. In contrast, methanotrophic potential activity, measured by pmoA transcript concentrations, did not vary with landscape type, but correlated with conductivity, phosphorus and total suspended solids. Methanotrophic potential activity was also detected in low-oxygen bottom waters, where it was inversely correlated with methane concentrations, suggesting methane depletion by methanotrophs. Methanotrophs were present and potentially active throughout the water column regardless of oxygen concentration, and may therefore be resilient to future mixing and oxygenation regimes in the warming subarctic. PMID:29182670

  2. Stability of hemostatic proteins in canine fresh-frozen plasma thawed with a modified commercial microwave warmer or warm water bath.

    Science.gov (United States)

    Pashmakova, Medora B; Barr, James W; Bishop, Micah A

    2015-05-01

    To compare stability of hemostatic proteins in canine fresh-frozen plasma (FFP) thawed with a modified commercial microwave warmer (MCM) or warm water bath (37°C; WWB) or at room temperature (22°C). Fresh-frozen plasma obtained from 8 canine donors of a commercial blood bank. A commercial microwave warmer was modified with a thermocouple to measure surface temperature of bags containing plasma. The MCM and a WWB were each used to concurrently thaw a 60-mL bag of plasma obtained from the same donor. Two 3-mL control aliquots of FFP from each donor were thawed to room temperature without use of a heating device. Concentrations of hemostatic proteins, albumin, and D-dimers; prothrombin time (PT); and activated partial thromboplastin time (aPTT) were determined for all samples. Significant decreases in concentrations of factors II, IX, X, XI, fibrinogen, von Willebrand factor, antithrombin, protein C, and albumin and significant increases in PT and aPTT were detected for plasma thawed with the MCM, compared with results for samples thawed with the WWB. Concentrations of factors VII, VIII, and XII were not significantly different between plasma thawed with the MCM and WWB. Concentrations of D-dimers were above the reference range for all thawed samples regardless of thawing method. No significant differences in factor concentrations were detected between control and WWB-thawed samples. Significant differences in hemostatic protein concentrations and coagulation times were detected for plasma thawed with an MCM but not between control and WWB-thawed samples. Clinical importance of these changes should be investigated.

  3. Behaviour of polycyclic aromatic hydrocarbons (PAH) in soils under freeze-thaw cycles

    Science.gov (United States)

    Zschocke, Anne; Schönborn, Maike; Eschenbach, Annette

    2010-05-01

    The arctic region will be one of the most affected regions by climate change due to the predicted temperature rise. As a result of anthropogenic actions as mining, exploration and refining as well as atmospheric transport pollutions can be found in arctic soils. Therefore questions on the behaviour of organic contaminants in permafrost influenced soils are of high relevance. First investigations showed that permafrost can act as a semi-permeable layer for PAH (Curtosi et al., 2007). Therefore it can be assumed that global warming could result in a mobilization of PAH in these permafrost influenced soils. On the other hand a low but detectable mineralization of organic hydrocarbons by microorganisms under repeated freeze-thaw cycles was analysed (Börresen et al. 2007, Eschenbach et al. 2000). In this study the behaviour and distribution of PAH under freezing and periodically freezing and thawing were investigated in laboratory column experiments with spiked soil materials. Two soil materials which are typical for artic regions, a organic matter containing melt water sand and a well decomposed peat, were homogeneously spiked with a composite of a crude oil and the PAH anthracene and benzo(a)pyrene. After 14days preincubation time the soil material was filled in the laboratory columns (40cm high and 10 cm in diameter). Based on studies by Chuvilin et al. (2001) the impact of freezing of the upper third of the column from the surface downwards was examined. The impact of freezing was tested in two different approaches the first one with a single freezing step and the second one with a fourfold repeated cycle of freezing and thawing which takes about 6 or 7 days each. The experimental design and very first results will be shown and discussed. In some experiments with the peat a higher concentration of anthracene and benzo(a)pyrene could be detected below the freezing front in the unfrozen part of the column. Whereas the concentration of PAH had slightly decreased in

  4. Long-term geoelectrical monitoring of laboratory freeze-thaw experiments on bedrock samples

    Science.gov (United States)

    Kuras, Oliver; Uhlemann, Sebastian; Murton, Julian; Krautblatter, Michael

    2014-05-01

    Much attention has recently focussed on the continuous and near-real-time geophysical monitoring of permafrost-affected bedrock with permanently installed sensor arrays. It is hoped that such efforts will enhance process understanding in such environments (permafrost degradation, weathering mechanisms) and augment our capability to predict future instabilities of rock walls and slopes. With regard to electrical methods for example, recent work has demonstrated that temperature-calibrated electrical resistivity tomography (ERT) is capable of imaging recession and re-advance of rock permafrost in response to the ambient temperature regime. However, field experience also shows that several fundamental improvements to ERT methodology are still required to achieve the desired sensitivity, spatial-temporal resolution and long-term robustness that must underpin continuous geophysical measurements. We have applied 4D geoelectrical tomography to monitoring laboratory experiments simulating permafrost growth, persistence and thaw in bedrock over a period of 26 months. Six water-saturated samples of limestone and chalk of varying porosity represented lithologies commonly affected by permafrost-related instability. Time-lapse imaging of the samples was undertaken during multiple successive freeze-thaw cycles, emulating annual seasonal change over several decades. Further experimental control was provided by simultaneous measurements of vertical profiles of temperature and moisture content within the bedrock samples. These experiments have helped develop an alternative methodology for the volumetric imaging of permafrost bedrock and tracking active layer dynamics. Capacitive resistivity imaging (CRI), a technique based upon low-frequency, capacitively-coupled measurements emulates ERT methodology, but without the need for galvanic contact on frozen rock. The latter is perceived as a key potential weakness, which could lead to significant limitations as a result of the variable

  5. Long Term Thawing Experiments on Intact Cores of Arctic Mineral Cryosol: Implications for Greenhouse Gas Feedbacks from Global Warming

    Science.gov (United States)

    Onstott, T. C.; Stackhouse, B. T.; Lau, C. Y. M.; Whyte, L. G.; Pfiffner, S. M.; Vishnivetskaya, T. A.

    2015-12-01

    Mineral cryosols comprise >87% of Arctic tundra. Much attention has focused on high-organic carbon cryosols and how they will respond to global warming. The biogeochemical processes related to the greenhouse gas release from mineral cryosols, however, have not been fully explored. To this end, seventeen intact cores of active layer and underlying permafrost of mineral cryosol from Axel Heiberg Island, Nunavut, Canada, were subjected to 85 weeks of thawing at 4.5°C under various treatment regimes. The fluxes of CO2 and CH4 across the atmosphere-soil boundary and vertical profiles of the gas and water chemistry and the metagenomes were determined. The flux measurements were compared to those of microcosms and field measurements. The main conclusions were as follows: 1) CO2 emission rates from the intact cores do not behave in the typical fast to slow carbon pool fashion that typify microcosm experiments. The CO2 emission rates from the intact cores were much slower than those from the microcosm initially, but steadily increased with time, overtaking and then exceeding microcosm release rates after one year. 2) The increased CO2 flux from thawing permafrost could not be distinguished from that of control cores until after a full year of thawing. 3) Atmospheric CH4 oxidation was present in all intact cores regardless of whether they are water saturated or not, but after one year it had diminished to the point of being negligible. Over that same time the period the metagenomic data recorded a significant decline in the proportion of high-affinity methanotrophs. 4) Thaw slumps in the cores temporarily increased the CH4 oxidation and the CO2 emission rates. 5) The microbial community structures varied significantly by depth with methanotrophs being more abundant in above 35 cm depth than below 35 cm depth. 6) Other than the diminishment of Type II methanotrophs, the microbial community structure varied little after one week of thawing, nor even after 18 months of thaw.

  6. Effect of thawing time, cooling rate and boron nutrition on freezing point of the primordial shoot in norway spruce buds.

    Science.gov (United States)

    Räisänen, Mikko; Repo, Tapani; Lehto, Tarja

    2006-04-01

    Effects of cooling rates on bud frost hardiness have been studied but there is little information on bud responses to thawing. Since the cell wall pore size has been found to increase with boron (B) deficiency, B deficiency may affect the supercooling ability of buds in winter. The effects of duration of thawing time and rate of cooling on bud frost hardiness of Norway spruce (Picea abies) were studied in a B fertilization trial in February 2003 and March 2005. Frost hardiness of apical buds was determined by differential thermal analysis (DTA) and visual scoring of damage. In 2003, the freezing point of primordial shoots of buds (T(f)), i.e. the low-temperature exotherm (LTE), was, on average, -39 degrees C when buds were thawed for less than 3 h and the T(f) increased to -21 degrees C after 18 h of thawing. During the first 4 h of thawing, the rate of dehardening was 6 degrees C h(-1). In 2005, buds dehardened linearly from -39 degrees C to -35 degrees C at a rate of 0.7 degrees C h(-1). In 2003, different cooling rates of 1-5 degrees C h(-1) had a minor effect on T(f) but in 2005 with slow cooling rates T(f) decreased. In both samplings, at cooling rates of 2 and 1 degrees C h(-1), T(f) was slightly higher in B-fertilized than in non-fertilized trees. By contrast, at very short thawing times in 2003, T(f) was somewhat lower in B-fertilized trees. There was little evidence of reduced frost hardiness in trees with low B status. This study showed that buds deharden rapidly when exposed to above-freezing temperatures in winter, but if cooled again they reharden more slowly. According to this study, rapid dehardening of buds has to be taken into account in assessments of frost hardiness.

  7. Dynamics of leaf gas exchange, chlorophyll fluorescence and stem diameter changes during freezing and thawing of Scots pine seedlings.

    Science.gov (United States)

    Lindfors, Lauri; Hölttä, Teemu; Lintunen, Anna; Porcar-Castell, Albert; Nikinmaa, Eero; Juurola, Eija

    2015-12-01

    Boreal trees experience repeated freeze-thaw cycles annually. While freezing has been extensively studied in trees, the dynamic responses occurring during the freezing and thawing remain poorly understood. At freezing and thawing, rapid changes take place in the water relations of living cells in needles and in stem. While freezing is mostly limited to extracellular spaces, living cells dehydrate, shrink and their osmotic concentration increases. We studied how the freezing-thawing dynamics reflected on leaf gas exchange, chlorophyll fluorescence and xylem and living bark diameter changes of Scots pine (Pinus sylvestris L.) saplings in controlled experiments. Photosynthetic rate quickly declined following ice nucleation and extracellular freezing in xylem and needles, almost parallel to a rapid shrinking of xylem diameter, while that of living bark followed with a slightly longer delay. While xylem and living bark diameters responded well to decreasing temperature and water potential of ice, the relationship was less consistent in the case of increasing temperature. Xylem showed strong temporal swelling at thawing suggesting water movement from bark. After thawing xylem diameter recovered to a pre-freezing level but living bark remained shrunk. We found that freezing affected photosynthesis at multiple levels. The distinct dynamics of photosynthetic rate and stomatal conductance reveals that the decreased photosynthetic rate reflects impaired dark reactions rather than stomatal closure. Freezing also inhibited the capacity of the light reactions to dissipate excess energy as heat, via non-photochemical quenching, whereas photochemical quenching of excitation energy decreased gradually with temperature in agreement with the gas exchange data. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  8. Destabilization of the plasma membrane of isolated plant protoplasts during a freeze-thaw cycle: the influence of cold acclimation

    Energy Technology Data Exchange (ETDEWEB)

    Steponkus, P.L.; Dowgert, M.F.; Gordon-Kamm, W.J.

    1983-01-01

    The functional characteristics of the plasma membrane in response to a free-thaw cycle are studied in isolated protoplasts with the plasma membrane still intact. Three different forms of injury have been characterized: intracellular ice formation, hypertonic-induced loss of osmotic responsiveness, and expansion-induced lysis. In this report, the influence of cold acclimation on the incidence of these forms of injury is emphasized. Isolated protoplasts are an excellent arena in which destabilization of the plasma membrane can be directly observed during a freeze-thaw cycle by cryomicroscopy. 65 references, 8 figures.

  9. Climate hazards caused by thawing permafrost? Background information of the Federal Environmental Agency; Klimagefahr durch tauenden Permafrost? UBA-Hintergrundpapier

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-08-15

    The thawing of permafrost regions is supposed to increase climatic change processes due to the released methane. During the last decades the temperature of permafrost soils has increased by several tenths of degree up to 2 deg C. It is supposed that 10 to 20% of the permafrost regions will thaw during the next 100 years. The southern boundary of the permafrost region will move several hundred kilometers toward the north. Besides the increased risk for the climate system there will also be disadvantageous consequences for the ecosystems. Negative economic consequences are already observed and will be enhanced in the futures with significant cost for the public.

  10. Controlled Freeze-thaw Experiments to Study Biogeochemical Process and its Effects on Greenhouse Gas Release in Arctic Soil Columns

    Science.gov (United States)

    Wu, Y.; Kneafsey, T. J.; Tas, N.; Bill, M.; Ulrich, C.; Hubbard, S. S.

    2014-12-01

    Greenhouse gas release associated with permafrost thawing is one of the largest uncertainties in future climate prediction. Improvement of such prediction relies on a better representation of the interactions between hydrological, geochemical and microbial processes in the Arctic ecosystem that occur over a wide range of space and time scales and under dynamic freeze-thaw conditions. As part of the Next Generation Ecosystem Experiments in the Arctic (NGEE-Arctic), we conducted controlled laboratory freeze-thaw experiments to study greenhouse gas release in vertical permafrost soil columns with vertically heterogeneous hydrological, geochemical and microbial properties. The studies were performed using soil cores collected from the NGEE Barrow, AK site. Two cores collected next to each other with very similar soil structures were used for the experiment. One of the cores was destructively sampled for baseline characterization, and the second core was used for the freeze-thaw experiments. The core extends from the ground surface into the permafrost with roughly 40 cm of active layer. The column was instrumented with various sensors and sampling devices, including thermocouples, geophysical (electrical) sensors, and sampling ports for solids and fluids. The headspace of the soil column was purged with CO2 free air and the gas samples were collected periodically for greenhouse gas analysis. Our initial tests simulated seasonal temperature variation from ~ -10°C to +10°C at the ground surface. Our results demonstrated that temperature and geophysical data provided real time information on the freeze thaw dynamics of the column and the surface greenhouse gas fluxes correlated with the freeze thaw stages and associated hydrological and biogeochemical processes in the vertical soil column. For example, surface fluxes data revealed an early burst of GHG concentrations during the initial thawing of the surface ice rich layer of the soil, indicating the presence of trapped

  11. Thermokarst and thaw-related landscape dynamics -- an annotated bibliography with an emphasis on potential effects on habitat and wildlife

    Science.gov (United States)

    Jones, Benjamin M.; Amundson, Courtney L.; Koch, Joshua C.; Grosse, Guido

    2013-01-01

    Permafrost has warmed throughout much of the Northern Hemisphere since the 1980s, with colder permafrost sites warming more rapidly (Romanovsky and others, 2010; Smith and others, 2010). Warming of the near-surface permafrost may lead to widespread terrain instability in ice-rich permafrost in the Arctic and the Subarctic, and may result in thermokarst development and other thaw-related landscape features (Jorgenson and others, 2006; Gooseff and others, 2009). Thermokarst and other thaw-related landscape features result from varying modes and scales of permafrost thaw, subsidence, and removal of material. An increase in active-layer depth, water accumulation on the soil surface, permafrost degradation and associated retreat of the permafrost table, and changes to lake shores and coastal bluffs act and interact to create thermokarst and other thaw-related landscape features (Shur and Osterkamp, 2007). There is increasing interest in the spatial and temporal dynamics of thermokarst and other thaw-related features from diverse disciplines including landscape ecology, hydrology, engineering, and biogeochemistry. Therefore, there is a need to synthesize and disseminate knowledge on the current state of near-surface permafrost terrain. The term "thermokarst" originated in the Russian literature, and its scientific use has varied substantially over time (Shur and Osterkamp, 2007). The modern definition of thermokarst refers to the process by which characteristic landforms result from the thawing of ice-rich permafrost or the melting of massive ice (van Everdingen, 1998), or, more specifically, the thawing of ice-rich permafrost and (or) melting of massive ice that result in consolidation and deformation of the soil surface and formation of specific forms of relief (Shur, 1988). Jorgenson (2013) identifies 23 distinct thermokarst and other thaw-related features in the Arctic, Subarctic, and Antarctic based primarily on differences in terrain condition, ground-ice volume

  12. Freeze and Thaw States Detection in High Latitude Inundated Areas Using High Resolution ALOS PALSAR Observations

    Science.gov (United States)

    Azarderakhsh, M.; McDonald, K. C.; Prakash, S.

    2016-12-01

    Inundated surfaces in Northern latitudes experience freeze and thaw (FT) cycles seasonally. These surfaces are among the important sources of positive carbon and methane (CH4) feedback to the atmosphere as well as their crucial role in biogeochemical transitions, hydrology and prediction of boreal-arctic ecosystem. Wetlands, in particular, are the regions that contribute mostly as a CH4 source. In the past, remote sensing observations from satellites have shown a great potential capability in detecting freeze and thaw states of the surfaces especially in remote areas. Active and passive microwave observations are shown to be more sensitive to the change of surface state and are more promissing than other observations because they are less affected by the atmosphere. Active microwave measurements such as the Advanced Land Observing Satellite Phased Array L-Band SAR (ALOS PALSAR) can provide a viable higher resolution estimates of the inundated surfaces and their states than those from passive microwave brightness temperatures with coarser and higher temporal observations. Therefore, the link between active and passive estimates may potentially enhance our understanding with the advantages of higher spatial and temporal predictions. In this study, we utilize PALSAR ScanSAR mode data with more frequent temporal coverage of up to 40 days along with the static map dervied from Fine Beam Data to study the timing of the inundation for wetland classes as well as their FT states using data from year 2007 to 2010 period. A pixel-based and object oriented-based classification methods to derive freeze/thaw maps is applied. The dynamic inundation maps then are developed at 100 m resolution. JERS and PALSAR Fine Beam mode based static wetlands map and Landsat Based land cover data (NLCD) are used to train and assess the classification at high resolution along with other ancillary data sets. The developed thresholds are employed for the FT detection. Comparison of the results

  13. Retrogressive thaw slumps temper dissolved organic carbon delivery to streams of the Peel Plateau, NWT, Canada

    Directory of Open Access Journals (Sweden)

    C. A. Littlefair

    2017-12-01

    Full Text Available In Siberia and Alaska, permafrost thaw has been associated with significant increases in the delivery of dissolved organic carbon (DOC to recipient stream ecosystems. Here, we examine the effect of retrogressive thaw slumps (RTSs on DOC concentration and transport, using data from eight RTS features on the Peel Plateau, NWT, Canada. Like extensive regions of northwestern Canada, the Peel Plateau is comprised of thick, ice-rich tills that were deposited at the margins of the Laurentide Ice Sheet. RTS features are now widespread in this region, with headwall exposures up to 30 m high and total disturbed areas often exceeding 20 ha. We find that intensive slumping on the Peel Plateau is universally associated with decreasing DOC concentrations downstream of slumps, even though the composition of slump-derived dissolved organic matter (DOM; assessed using specific UV absorbance and slope ratios is similar to permafrost-derived DOM from other regions. Comparisons of upstream and downstream DOC flux relative to fluxes of total suspended solids suggest that the substantial fine-grained sediments released by RTS features may sequester DOC. Runoff obtained directly from slump rill water, above entry into recipient streams, indicates that the deepest RTS features, which thaw the greatest extent of buried, Pleistocene-aged glacial tills, release low-concentration DOC when compared to paired upstream, undisturbed locations, while shallower features, with exposures that are more limited to a relict Holocene active layer, have within-slump DOC concentrations more similar to upstream sites. Finally, fine-scale work at a single RTS site indicates that temperature and precipitation serve as primary environmental controls on above-slump and below-slump DOC flux, but it also shows that the relationship between climatic parameters and DOC flux is complex for these dynamic thermokarst features. These results demonstrate that we should expect clear variation in

  14. Tracer-based identification of rock glacier thawing in a glacierized Alpine catchment

    Science.gov (United States)

    Engel, Michael; Penna, Daniele; Tirler, Werner; Comiti, Francesco

    2017-04-01

    Current warming in high mountains leads to increased melting of snow, glacier ice and permafrost. In particular rock glaciers, as a creeping form of mountain permafrost, may release contaminants such as heavy metals into the stream during intense melting periods in summer. This may have strong impacts on both water quantity and quality of fresh water resources but might also harm the aquatic fauna in mountain regions. In this context, the present study used stable isotopes of water and electrical conductivity (EC) combined with trace, major and minor elements to identify the influence of permafrost thawing on the water quality in the glacierized Solda catchment (130 km2) in South Tyrol (Italy). We carried out a monthly sampling of two springs fed by an active rock glacier at about 2600 m a.s.l. from July to October 2015. Furthermore, we took monthly water samples from different stream sections of the Solda River (1110 to m a.s.l.) from March to November 2015. Meteorological data were measured by an Automatic Weather Station at 2825 m a.s.l. of the Hydrographic Office (Autonomous Province of Bozen-Bolzano). First results show that water from the rock glacier springs and stream water fell along the global meteoric water line. Spring water was slightly more variable in isotopic ratio (δ2H: -91 to - 105 ) and less variable in dissolved solutes (EC: 380 to 611 μS/cm) than stream water (δ2H: -96 to - 107 ‰ and EC: 212 to 927 μS/cm). Both spring water and stream water showed a pronounced drop in EC during July and August, very likely induced by increased melt water dilution. In both water types, element concentrations of Ca and Mg were highest (up to 160 and 20 mg/l, respectively). In September, spring water showed higher concentrations in Cu, As, and Pb than stream water, indicating that these elements partly exceeded the concentration limit for drinking water. These observations highlight the important control, which rock glacier thawing may have on water quality

  15. Chilled and post-thaw storage of sperm in different goldfish types.

    Science.gov (United States)

    Bernáth, G; Ittzés, I; Szabó, Z; Horváth, Á; Krejszeff, S; Lujić, J; Várkonyi, L; Urbányi, B; Bokor, Z

    2017-08-01

    The effective storage time of sperm after stripping (for 48 hr in 6-hr intervals) and after thawing (for 6 hr in 2-hr intervals) in Black moor, Oranda and Calico goldfish types was investigated. Variations in sperm density were also measured in all lines. The efficiency of a sperm cryopreservation method formerly developed for common carp was recorded in all three goldfish lines. Motility parameters ((pMOT, %), curvilinear velocity (VCL, μm/s) and straightness (STR, %)) of Black moor sperm did not decrease significantly during 48 hr of storage. A significant reduction in the Oranda type compared to the fresh control was observed in pMOT after 42 (23 ± 2%) and VCL after 36 (94 ± 12 μm/s) hours (pMOT 84 ± 5%, VCL 150 ± 11 μm/s). In the Calico type, pMOT decreased significantly already after 18 (42 ± 26%) and VCL after 6 (105 ± 8 μm/s) hours (fresh: pMOT 92 ± 5%, VCL 151 ± 6 μm/s). A high pMOT immediately following thawing was measured in Oranda (46 ± 12%) and Calico (55 ± 15%) types, whereas a reduced pMOT was recorded in Black moor (24 ± 19%). In Calico, pMOT showed a significant reduction after 6 hr (19 ± 11%) in comparison with the initial value, with no changes observed in VCL and STR. None of the parameters changed in the Black moor and Oranda types. Evidence was found that different goldfish lines have different sperm quality and characteristics. Further studies can investigate the possible effects of chilled and post-thaw storage on the fertilizing capacity of sperm in the Black moor, Oranda and Calico goldfish types. © 2017 Blackwell Verlag GmbH.

  16. Retrogressive thaw slumps temper dissolved organic carbon delivery to streams of the Peel Plateau, NWT, Canada

    Science.gov (United States)

    Littlefair, Cara A.; Tank, Suzanne E.; Kokelj, Steven V.

    2017-12-01

    In Siberia and Alaska, permafrost thaw has been associated with significant increases in the delivery of dissolved organic carbon (DOC) to recipient stream ecosystems. Here, we examine the effect of retrogressive thaw slumps (RTSs) on DOC concentration and transport, using data from eight RTS features on the Peel Plateau, NWT, Canada. Like extensive regions of northwestern Canada, the Peel Plateau is comprised of thick, ice-rich tills that were deposited at the margins of the Laurentide Ice Sheet. RTS features are now widespread in this region, with headwall exposures up to 30 m high and total disturbed areas often exceeding 20 ha. We find that intensive slumping on the Peel Plateau is universally associated with decreasing DOC concentrations downstream of slumps, even though the composition of slump-derived dissolved organic matter (DOM; assessed using specific UV absorbance and slope ratios) is similar to permafrost-derived DOM from other regions. Comparisons of upstream and downstream DOC flux relative to fluxes of total suspended solids suggest that the substantial fine-grained sediments released by RTS features may sequester DOC. Runoff obtained directly from slump rill water, above entry into recipient streams, indicates that the deepest RTS features, which thaw the greatest extent of buried, Pleistocene-aged glacial tills, release low-concentration DOC when compared to paired upstream, undisturbed locations, while shallower features, with exposures that are more limited to a relict Holocene active layer, have within-slump DOC concentrations more similar to upstream sites. Finally, fine-scale work at a single RTS site indicates that temperature and precipitation serve as primary environmental controls on above-slump and below-slump DOC flux, but it also shows that the relationship between climatic parameters and DOC flux is complex for these dynamic thermokarst features. These results demonstrate that we should expect clear variation in thermokarst

  17. Observations on procedures for thawing and spit-roasting frozen dressed chickens, and post-cooking care and storage: with particular reference to food-poisoning bacteria.

    Science.gov (United States)

    Roberts, D

    1972-09-01

    A comparison was made of four methods of thawing frozen chickens and an average thaw time for each method was determined.Fully and partially thawed chickens, inoculated with salmonellas, Clostridium welchii and Staphylococcus aureus were cooked in a spit-roasting oven at different temperatures for different lengths of time. The chickens were examined freshly cooked and after storage under various conditions.Spit roasting fully thawed chickens until the outer skin was golden brown was sufficient heat-treatment to kill salmonellas and Staph. aureus but Cl. welchii could survive. Salmonellas could also survive if the chickens were not fully thawed before cooking.Incorrect storage after cooking was shown to encourage the growth of pathogens.The incidence of intestinal pathogens in frozen dressed chickens and environmental hazards in spit-roasting establishments were also studied. Of raw chickens examined 35% contained salmonellas (9 serotypes), 63% contained Cl. welchii and 63% Staph. aureus.

  18. Long-term serological outcome of infants who received frozen-thawed milk from human T-lymphotropic virus type-I positive mothers.

    Science.gov (United States)

    Ando, Yoshiya; Ekuni, Yutaka; Matsumoto, Yoshinari; Nakano, Shiro; Saito, Kensuke; Kakimoto, Kazuhiro; Tanigawa, Takuo; Kawa, Motohiro; Toyama, Takenori

    2004-12-01

    Human T-lymphotropic virus type-I (HTLV-I) infection occurs via mothers' milk during feeding. However, freeze-thaw processing can eliminate the infectivity of the mother's milk of HTLV-I carriers. A long-term follow-up survey was conducted to investigate the HTLV-I infectivity of frozen-thawed mothers' milk among infants whose mothers were HTLV-I seropositive. Infants fed frozen-thawed mothers' milk did not become HTLV-I antibody-positive up until 1 year old, and all children followed up until an age of 11-12 years were antibody negative. This study showed that freeze-thaw processing can eliminate the HTLV-I infectivity of mothers' milk, and that HTLV-I carriers can indirectly feed their infants using frozen-thawed mothers' milk as a way to prevent HTLV-I infection.

  19. Effect of low density lipoprotein on DNA integrity of freezing-thawing boar sperm by neutral comet assay.

    Science.gov (United States)

    Jiang, Zhong-Liang; Li, Qing-Wang; Li, Wen-Ye; Hu, Jian-Hong; Zhao, Hong-Wei; Zhang, Shu-Shan

    2007-06-01

    A modified protocol of neutral comet assay was utilized to assess the effect of low density lipoprotein (LDL) on the DNA integrity of boar freezing-thawing semen. The results demonstrated that the method was high sensitive and easier manipulation and LDL significantly protected sperm DNA integrity (psperm DNA in cryopreservation 0 day and 30 days (p>0.05).

  20. Thawed cod fillets spoil less rapidly than unfrozen fillets when stored under modified atmosphere at 2 C

    DEFF Research Database (Denmark)

    Guldager, H.S.; Bøknæs, Niels; Østerberg, Carsten

    1998-01-01

    as reflected both in chemical analyses and sensory evaluation. In contrast to fresh MAP cod fillets no significant production of trimethylamine occurred and almost no amine odor and taste were detected during 20 days of chill storage of thawed MAP cod fillets. The use of frozen fillets as raw material not only...

  1. Negative effect of combined cysteine and glutathione in soy lecithin-based extender on post-thawed ram spermatozoa.

    Science.gov (United States)

    Zhandi, Mahdi; Sharafi, Mohsen

    2015-09-01

    This study was conducted to evaluate the effect of combined cysteine and glutathione in soy lecithin-based semen extender on post-thawed ram sperm quality. A total of 28 ejaculates were collected twice a week (from four rams) during breeding season. In each replicate, semen samples (n = 4, one ejaculate for each ram) were pooled and divided into three equal parts, and each part was diluted with one of following extender: (1) soy lecithin-based extender containing no cysteine and no glutathione (C0-G0), (2) soy lecithin-based extender containing cysteine (5 mM) and glutathione (5 mM) (C5-G5), and (3) soy lecithin-based extender containing cysteine (10 mM) and glutathione (10 mM) (C10-G10). After freeze-thawing process, motility and velocity parameters, plasma membrane integrity and functionality, mitochondrial activity, and apoptosis features of spermatozoa were evaluated. The obtained results showed that total and progressive motility, plasma membrane integrity and functionality, and live post-thawed spermatozoa was lower in C10-G10 extender compared to C0-G0 and C5-G5 extenders (P 0.05). In conclusion, it seems that high concentration of combined cysteine and glutathione in soy lecithin-based semen extender has a detrimental effect of post-thawed ram sperm quality.

  2. Mathematical modeling of the heat transfer for determining the depth of thawing basin buildings with long service life

    Science.gov (United States)

    Sirditov, Ivan; Stepanov, Sergei

    2017-11-01

    In this paper, a numerical study of the problem of determining a thawing basin in the permafrost soil for buildings with a long service life is carried out using two methods, with the formulas of set of rules 25.13330.2012 "Soil bases and foundations on permafrost soils" and using a mathematical model.

  3. Interannual variability of plant phenology in tussock tundra: modelling interactions of plant productivity, plant phenology, snowmelt and soil thaw

    NARCIS (Netherlands)

    Wijk, van M.T.; Williams, M.; Laundre, J.A.; Shaver, G.R.

    2003-01-01

    We present a linked model of plant productivity, plant phenology, snowmelt and soil thaw in order to estimate interannual variability of arctic plant phenology and its effects on plant productivity. The model is tested using 8 years of soil temperature data, and three years of bud break data of

  4. Freezing tolerance of winter wheat as influenced by extended growth at low temperature and exposure to freeze-thaw cycles

    Science.gov (United States)

    As the seasons progress, autumn-planted winter wheat plants (Triticum aestivum L.) first gain, then progressively lose freezing tolerance. Exposing the plants to freeze-thaw cycles of -3/3°C results in increased ability to tolerate subsequent freezing to potentially damaging temperatures. This stu...

  5. Responses of Antarctic soil microbial communities and associated functions to temperature and freeze-thaw cycle frequency.

    NARCIS (Netherlands)

    Yergeau, E.; Kowalchuk, G.A.

    2008-01-01

    Climatic changes will not only result in higher overall temperature, but also in greater variability in weather conditions. Antarctic soils are subjected to extremely variable conditions in the form of frequent freeze-thaw cycles (FTCs), but the importance of alteration in FTC frequency, compared

  6. Responses of Antarctic soil microbial communities and associated functions to temperature and freeze-thaw cycle frequency

    NARCIS (Netherlands)

    Yergeau, E.; Kowalchuk, G.A.

    2008-01-01

    Climatic changes will not only result in higher overall temperature, but also in greater variability in weather conditions. Antarctic soils are subjected to extremely variable conditions in the form of frequent freeze–thaw cycles (FTCs), but the importance of alteration in FTC frequency, compared

  7. Freeze-thaw regime effects on carbon and nitrogen dynamics in sub-arctic heath tundra mesocosms

    DEFF Research Database (Denmark)

    Grogan, P.; Michelsen, A.; Ambus, P.

    2004-01-01

    of which is realistic of in situ spatial and temporal variation in field conditions, on C and N dynamics in sub-arctic heath tundra mesocosms. In addition, N-15 isotopic label was used to follow the partitioning of a labile N pool between major ecosystem components, both during the freeze-thaw treatments...

  8. Freezing and thawing effects on fat, protein, and lactose levels of human natural milk administered by gavage and continuous infusion

    Directory of Open Access Journals (Sweden)

    Andrea D. Abranches

    2014-07-01

    Full Text Available OBJECTIVES: to analyze the changes in human milk macronutrients: fat, protein, and lactose in natural human milk (raw, frozen and thawed, after administration simulation by gavage and continuous infusion. METHOD: an experimental study was performed with 34 human milk samples. The infrared spectrophotometry using the infrared analysis equipment MilkoScan Minor(r (Foss, Denmark equipment was used to analyze the macronutrients in human milk during the study phases. The analyses were performed in natural (raw samples and after freezing and fast thawing following two steps: gavage and continuous infusion. The non-parametric Wilcoxon test for paired samples was used for the statistical analysis. RESULTS: the fat content was significantly reduced after administration by continuous infusion (p < 0.001 during administration of both raw and thawed samples. No changes in protein and lactose content were observed between the two forms of infusion. However, the thawing process significantly increased the levels of lactose and milk protein. CONCLUSION: the route of administration by continuous infusion showed the greatest influence on fat loss among all the processes required for human milk administration.

  9. Freezing and thawing effects on fat, protein, and lactose levels of human natural milk administered by gavage and continuous infusion.

    Science.gov (United States)

    Abranches, Andrea D; Soares, Fernanda V M; Junior, Saint-Clair G; Moreira, Maria Elisabeth L

    2014-01-01

    to analyze the changes in human milk macronutrients: fat, protein, and lactose in natural human milk (raw), frozen and thawed, after administration simulation by gavage and continuous infusion. an experimental study was performed with 34 human milk samples. The infrared spectrophotometry using the infrared analysis equipment MilkoScan Minor® (Foss, Denmark) equipment was used to analyze the macronutrients in human milk during the study phases. The analyses were performed in natural (raw) samples and after freezing and fast thawing following two steps: gavage and continuous infusion. The non-parametric Wilcoxon test for paired samples was used for the statistical analysis. the fat content was significantly reduced after administration by continuous infusion (p<0.001) during administration of both raw and thawed samples. No changes in protein and lactose content were observed between the two forms of infusion. However, the thawing process significantly increased the levels of lactose and milk protein. the route of administration by continuous infusion showed the greatest influence on fat loss among all the processes required for human milk administration. Copyright © 2014 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.

  10. Freshness assessment of thawed and chilled cod fillets packed in modified atmosphere using near-infrared spectroscopy

    DEFF Research Database (Denmark)

    Bøknæs, Niels; Jensen, K.N.; Andersen, Charlotte Møller

    2002-01-01

    products were determined on the same cod fillets. The purpose was to evaluate the potential of NIR spectroscopy for estimating (i) frozen storage temperature, (ii) frozen storage period and (iii) chill storage period of thawed-chilled MAP Barents Sea cod fillets. Furthermore, the potential for measuring...

  11. The combined effect of freeze thaw events and heavy metal pollution leads to distinct lethal synergy in Enchytraeus albidus

    DEFF Research Database (Denmark)

    Boas, Sara Wincentz; Slotsbo, Stine; Holmstrup, Martin

    Many anthropogenic activities negatively affect the environment and stress the organisms living here in various ways. Due to global warming it is likely that freeze-thaw events will replace permanent freezing of soils in arctic regions. Metals are some of the most common contaminants in soil in E...

  12. The choice of a suitable oligosaccharide to prevent aggregation of PEGylated nanoparticles during freeze thawing and freeze drying

    NARCIS (Netherlands)

    Hinrichs, Wouter; Manceñido, F A; Sanders, N N; Braeckmans, K; De Smedt, S C; Demeester, J; Frijlink, H W

    2006-01-01

    In a previous Study we have shown that the oligosaccharide inulin can prevent aggregation of poly(ethylene glycol) (PEG) coated plasmid DNA/cationic liposome complexes ('' PEGylated lipoplexes '') during freeze thawing and freeze drying [Hinrichs et al., 2005. J. Control. Release 103, 465]. By

  13. In vitro development of donated frozen-thawed human embryos in a prototype static microfluidic device: a randomized controlled trial

    NARCIS (Netherlands)

    Kieslinger, Dorit C.; Hao, Zhenxia; Vergouw, Carlijn G.; Kostelijk, Elisabeth H.; Lambalk, Cornelis B.; le Gac, Severine

    Objective: To compare the development of human embryos in microfluidic devices with culture in standard microdrop dishes, both under static conditions. Design: Prospective randomized controlled trial. Setting: In vitro fertilization laboratory. Patient(s): One hundred eighteen donated frozen-thawed

  14. Future active layer dynamics and carbon dioxide production from thawing permafrost layers in Northeast Greenland

    DEFF Research Database (Denmark)

    Hollesen, Jørgen; Elberling, Bo; Jansson, P.E.

    2011-01-01

    from a moist permafrost soil in High-Arctic Greenland with observed heat production and carbon dioxide (CO2) release rates from decomposition of previously frozen organic matter. Observations show that the maximum thickness of the active layer at the end of the summer has increased 1 cm yr-1 since 1996......Thawing permafrost and the resulting mineralization of previously frozen organic carbon (C) is considered an important future feedback from terrestrial ecosystems to the atmosphere. Here, we use a dynamic process oriented permafrost model, the CoupModel, to link surface and subsurface temperatures....... The model is successfully adjusted and applied for the study area and shown to be able to simulate active layer dynamics. Subsequently, the model is used to predict the active layer thickness under future warming scenarios. The model predicts an increase of maximum active layer thickness from today 70 to 80...

  15. The Batagay permafrost mega thaw slump: an environmental archive of the Late Pleistocene continental climate

    Science.gov (United States)

    Ashastina, Kseniia; Kienast, Frank; Römermann, Christine; Kuzmina, Svetlana; Diekmann, Bernhard; Schirrmeister, Lutz

    2017-04-01

    Palaeoenvironmental data preserved in permafrost contribute in our understanding of climate changes and their influence on the biocenoses during the Late Quaternary. Here we present cryolithological and palaeoecological results of studies carried out on a newly described permafrost exposure near Batagay about 50 km from Verkhoyansk, Sakha Republic, Russia, the town with the most continental climate recorded in the northern hemisphere. According to Günther et al. (2015), this unique exposure is the biggest mega thaw slump measured so far with the dimensions 800 m wide and 73 m deep. Only sparse data on the exposure are so far published in few articles (Novgorodov et al., 2013; Kunitsky et al., 2013; Ashastina et al., in press; Murton et al., 2016). The site is situated inWest Beringia, the Late Quaternary landmasscovered by tundra steppe and inhabited by diverse mega herbivores. We analyzed sedimentological data, plant macro- and micro-fossils together with insect remains in order to reconstruct the changes in the biome. The temporal frame for the accumulation of the sequence is provided by radiocarbon and optical stimulated luminescence dating, according to which the formation of the sequence started in the late Middle Quaternary. The features of permafrost accumulation and sedimentation give us an opportunity to propose the landscape changes responding to the climatic pulses of Pleistocene at this particular place. The shifts in vegetation from taiga to steppe associations are in a line with stadial and intersadial events. We propose a scheme of permafrost state and vegetation changes and merge it with climate variation during Late Quaternary. Ashastina, K., Schirrmeister, L., Fuchs, M., Kienast, F.: Pleistocene climate characteristics in the most continental part of the northern hemisphere: insights from cryolithological features of the Batagay mega thaw slump in the Siberian Yana Highlands. Climate of the Past, in press. doi: 10.5194/cp-2016-84. Günther, F

  16. Small thaw ponds: an unaccounted source of methane in the Canadian high Arctic.

    Science.gov (United States)

    Negandhi, Karita; Laurion, Isabelle; Whiticar, Michael J; Galand, Pierre E; Xu, Xiaomei; Lovejoy, Connie

    2013-01-01

    Thawing permafrost in the Canadian Arctic tundra leads to peat erosion and slumping in narrow and shallow runnel ponds that surround more commonly studied polygonal ponds. Here we compared the methane production between runnel and polygonal ponds using stable isotope ratios, ¹⁴C signatures, and investigated potential methanogenic communities through high-throughput sequencing archaeal 16S rRNA genes. We found that runnel ponds had significantly higher methane and carbon dioxide emissions, produced from a slightly larger fraction of old carbon, compared to polygonal ponds. The methane stable isotopic signature indicated production through acetoclastic methanogenesis, but gene signatures from acetoclastic and hydrogenotrophic methanogenic Archaea were detected in both polygonal and runnel ponds. We conclude that runnel ponds represent a source of methane from potentially older C, and that they contain methanogenic communities able to use diverse sources of carbon, increasing the risk of augmented methane release under a warmer climate.

  17. Modification of membrane cholesterol and its impact on frozen-thawed chicken sperm characteristics.

    Science.gov (United States)

    Partyka, Agnieszka; Bonarska-Kujawa, Dorota; Sporniak, Marta; Strojecki, Maciej; Niżański, Wojciech

    2016-10-01

    This study was conducted to determine the changes in chicken sperm plasma membranes fluidity and polarity as lipid packing arrangement induced by cholesterol-loaded cyclodextrin (CLC) and 2-hydroxypropyl-β-cyclodextrin (HBCD) and how sperm cryopreservation outcomes are improved by these changes. Treatment with 2 mg HBCD supported the highest (P sperm motility was highest in 2 mg HBCD (P sperm treated with 1 or 2 mg CLC showed the highest anisotropy at 5, 21, 25 and 40°C (P sperm membranes, increasing their fluidity and preventing them against membrane phase transition to gel, thus minimizing freezing-thaw sperm damage. HBCD treatment enhances chicken sperm viability and motility after cryopreservation and subsequent storage. This novel procedure may be useful for improving the technology for cryopreservation of fowl spermatozoa.

  18. Freeze-thaw stability of rice starch modified by Improved Extrusion Cooking Technology.

    Science.gov (United States)

    Ye, Jiangping; Hu, Xiuting; Zhang, Fang; Fang, Chong; Liu, Chengmei; Luo, Shunjing

    2016-10-20

    This study aimed to explore freeze-thaw (FT) stability of rice starch modified by Improved Extrusion Cooking Technology (IECT). FT stability of IECT-modified rice starch was investigated and compared with native one. Syneresis and SEM analysis showed that IECT-modified rice starch had better FT stability than native starch. Furthermore, IECT-modified rice starch had less significant changes in the rheological parameters during the FT cycles than the native starch. XRD and iodine binding analysis demonstrated that IECT treatment inhibited the association of rice starch, especially amylose retrogradation. Additionally, the peak at around 20° was detected in XRD patterns of IECT-modified rice starch, which confirmed the formation of amylose-lipid complex during the IECT treatment. These results suggested that the IECT treatment could improve FT stability of rice starch, which was ascribed to inhibition of starch retrogradation by IECT. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

  19. Comportement au dégel des sols silteux Thaw Behavior in Silty Soils

    Directory of Open Access Journals (Sweden)

    Montarges R.

    2006-11-01

    Full Text Available Les problèmes géotechniques relatifs à l'offshore arctique concernent essentiellement le tassement et la dégradation mécanique des sols au dégel. Dans la perspective d'évaluation de l'importance de ces problèmes l'IFP, avec le concours du Laboratoire de Glaciologie et Géophysique de l'environnement, a entrepris en 1986-87, une étude méthodologique des sols au dégel. Deux sols silteux (un silt sableux et un silt argileux, de comportement au gel très différent, ont été utilisés pour cette étude préliminaire. L'interprétation des résultats obtenus, dans les domaines de la structure des sols gelés et de l'évolution de leurs caractéristiques mécaniques (tassement et résistance au cisaillement, montre l'influence prédominante de la présence des minéraux argileux. Les résultats de cette étude préliminaire sont brièvement examinés en terme d'application aux problèmes d'exploitation pétrolière en zones arctiques. La poursuite de l'expérimentation apparaît nécessaire notamment pour évaluer correctement l'incidence du comportement au dégel des sols sur la subsidence associée aux risques d'instabilité des conduites rigides ou flexibles. Geotechnical problems related to offshore arctic activities mainly concern the settling and mechanical degradation of soils as the result of thawing. In the outlook for assessing the importance of such problems, IFP, with the assistance of the Laboratoire de Glaciologie et Géophysique de l'Environnement, began methodological research in 1986-1987 on the effect of thawing on soils. Two silty soils (one sandy silt and one clayey silt having very different thaw behaviors were used for this preliminary study. The interpretation of the results obtained in the fields of frozen soil structure and the evolution of their mechanical properties (settling and shear strength shows the predominant influence of the presence of clayey minerals. The results of this preliminary study are examined

  20. Freezing, thawing and aging effects on beef tenderness from Bos indicus and Bos taurus cattle.

    Science.gov (United States)

    Aroeira, Carolina N; Torres Filho, Robledo A; Fontes, Paulo Rogério; Gomide, Lúcio Alberto M; Ramos, Alcinéia L S; Ladeira, Márcio M; Ramos, Eduardo M

    2016-06-01

    The objective of this study was to determine the effects of freezing prior to aging on the meat tenderness of young Nellore and Aberdeen Angus bulls. Samples of the longissimus thoracis muscle were submitted to two treatments: conventional aging and freezing (-20°C for 40 days) followed by thawing and aging periods. The meats were evaluated after 0, 7, 14 and 21 aging days (1°C). Freezing increased (PFreezing increased proteolysis during aging in the meats of both breeds, but reduced shear force was found (Pfreezing prior to aging may contribute to meat tenderness in the first weeks of aging, but it is dependent on the animal breed. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Monitoring of Freeze-Thaw Cycles in Concrete Using Embedded Sensors and Ultrasonic Imaging

    Directory of Open Access Journals (Sweden)

    Javier Ranz

    2014-01-01

    Full Text Available This paper deals with the study of damage produced during freeze-thaw (F-T cycles using two non-destructive measurement approaches—the first approach devoted to continuous monitoring using embedded sensors during the cycles, and the second one, performing ultrasonic imaging before and after the cycles. Both methodologies have been tested in two different types of concrete specimens, with and without air-entraining agents. Using the first measurement approach, the size and distribution of pores were estimated using a thermoporometrical model and continuous measurements of temperature and ultrasonic velocity along cycles. These estimates have been compared with the results obtained using mercury porosimetry testing. In the second approach, the damage due to F-T cycles has been evaluated by automated ultrasonic transmission and pulse-echo inspections made before and after the cycles. With these inspections the variations in the dimensions, velocity and attenuation caused by the accelerated F-T cycles were determined.

  2. Effects of caffeine supplementation in post-thaw human semen over different incubation periods.

    Science.gov (United States)

    Pariz, J R; Hallak, J

    2016-11-01

    This study aimed to evaluate the effects of caffeine supplementation in post-cryopreservation human semen over different incubation periods. After collection by masturbation, 17 semen samples were analysed according to World Health Organization criteria, processed and cryopreserved with TEST-yolk buffer (1 : 1) in liquid nitrogen. After a thawing protocol, samples were incubated with 2 mm of caffeine for 0, 5, 15, 30 or 60 min, followed by analysis of motility and mitochondrial activity using 3,3'-diaminobenzidine (DAB). Mean variance analysis was performed, and P caffeine was associated with an increase in sperm motility, particularly 15-min incubation, suggesting that incubation with caffeine can be an important tool in patients with worsening seminal quality undergoing infertility treatment. © 2016 Blackwell Verlag GmbH.

  3. Estimation of Mercury Storage in Permafrost and Potential Release to the Environment by Thaw

    Science.gov (United States)

    Schuster, P. F.; Kamark, B. L.; Striegl, R. G.; Aiken, G.

    2011-12-01

    Changing climatic conditions in northern regions are causing perennially frozen soils (permafrost) to thaw. This thawing may have major implications for the cycling of carbon and metals, particularly mercury (Hg) in arctic and subarctic ecosystems. Hg is a ubiquitous pollutant that can impact aquatic resources and pose serious threat to human health. Northern regions of the world have the potential to contribute substantially to the global Hg cycling pool due to 1) enhanced deposition as a result of arctic springtime Hg depletion events, 2) increasing atmospheric Hg sources from rapidly expanding Asian industrialization, and perhaps most significantly, 3) the release of Hg historically sequestered in permafrost due to recent and potential future thawing. Total Hg concentrations (THg) were measured in three permafrost cores collected within the Yukon River basin of Alaska. Core 1, averaging 38 percent organic matter, was collected in a low-lying region of black spruce underlain by continuous permafrost; Core 2, a mineral-rich core averaging 8 percent organic matter, was collected in an upland region on a north facing slope of white spruce underlain by discontinuous permafrost; Core 3, also an organic-rich core, was collected in a low-lying collapsed bog region of discontinuous permafrost. All three cores were subsampled for THg at 1-2 cm intervals and represent a large range of permafrost soil conditions extending back about 10,000 years. Preliminary results show THg concentrations were highly variable ranging from 67 to 207 ng per g of soil (dry weight, n=94). Core 1 exhibited elevated Hg concentrations (50% above the mean) spanning several thousand years. Core 2 contained a lens of lightly-colored material (likely volcanic ash known as the White River Tephra based on XRD analysis) coincident with the some of the highest Hg concentrations in all three cores. Studies have shown that volcanic ash may have elevated concentrations of Hg. Preliminary estimates for the

  4. Multiscale model of a freeze-thaw process for tree sap exudation

    CERN Document Server

    Graf, Isabell; Stockie, John M

    2015-01-01

    Sap transport in trees has long fascinated scientists, and a vast literature exists on experimental and modelling studies of trees during the growing season when large negative stem pressures are generated by transpiration from leaves. Much less attention has been paid to winter months when trees are largely dormant but nonetheless continue to exhibit interesting flow behaviour. A prime example is sap exudation, which refers to the peculiar ability of sugar maple (Acer saccharum) and related species to generate positive stem pressure while in a leafless state. Experiments demonstrate that ambient temperatures must oscillate about the freezing point before significantly heightened stem pressures are observed, but the precise causes of exudation remain unresolved. The prevailing hypothesis attributes exudation to a physical process combining freeze-thaw and osmosis, which has some support from experimental studies but remains a subject of active debate. We address this knowledge gap by developing the first math...

  5. Greenhouse gas fluxes in a drained peatland forest during spring frost-thaw event

    Directory of Open Access Journals (Sweden)

    M. K. Pihlatie

    2010-05-01

    Full Text Available Fluxes of greenhouse gases (GHG carbon dioxide (CO2, methane (CH4 and nitrous oxide (N2O were measured during a two month campaign at a drained peatland forest in Finland by the eddy covariance (EC technique (CO2 and N2O, and automatic and manual chambers (CO2, CH4 and N2O. In addition, GHG concentrations and soil parameters (mineral nitrogen, temperature, moisture content in the peat profile were measured. The aim of the measurement campaign was to quantify the GHG fluxes during freezing and thawing of the top-soil, a time period with potentially high GHG fluxes, and to compare different flux measurement methods. The forest was a net CO2 sink during the two months and the fluxes of CO2 dominated the GHG exchange. The peat soil was a small sink of atmospheric CH4 and a small source of N2O. Both CH4 oxidation and N2O production took place in the top-soil whereas CH4 was produced in the deeper layers of the peat, which were unfrozen throughout the measurement period. During the frost-thaw events of the litter layer distinct peaks in CO2 and N2O emissions were observed. The CO2 peak followed tightly the increase in soil temperature, whereas the N2O peak occurred with a delay after the thawing of the litter layer. CH4 fluxes did not respond to the thawing of the peat soil. The CO2 and N2O emission peaks were not captured by the manual chambers and hence we conclude that high time-resolution measurements with automatic chambers or EC are necessary to quantify fluxes during peak emission periods. Sub-canopy EC measurements and chamber-based fluxes of CO2 and N2O were comparable, although the fluxes of N2O measured by EC were close to the detection limit of the system. We conclude

  6. Changing Arctic ecosystems: sea ice decline, permafrost thaw, and benefits for geese

    Science.gov (United States)

    Flint, Paul; Whalen, Mary; Pearce, John M.

    2014-01-01

    Through the Changing Arctic Ecosystems (CAE) initiative, the U.S. Geological Survey (USGS) strives to inform resource management decisions for Arctic Alaska by providing scientific information on current and future ecosystem response to a warming climate. A key area for the USGS CAE initiative has been the Arctic Coastal Plain of northern Alaska. This region has experienced a warming trend over the past 30 years, leading to reductions in sea ice and thawing of permafrost. Loss of sea ice has increased ocean wave action, leading to erosion and salt water inundation of coastal habitats. Saltwater tolerant plants are now thriving in these areas and this appears to be a positive outcome for geese in the Arctic. This finding is contrary to the deleterious effects that declining sea ice is having on habitats of ice-dependent animals, such as polar bear and walrus.

  7. Chloride Transport in OPC Concrete Subjected to the Freeze and Thaw Damage

    Directory of Open Access Journals (Sweden)

    Ki Yong Ann

    2017-01-01

    Full Text Available To predict the durability of a concrete structure under the coupling degradation consisting of the frosting and chloride attack, microstructural analysis of the concrete pore structure should be accompanied. In this study, the correlation between the pore structure and chloride migration for OPC concrete was evaluated at the different cement content in the concrete mix accounting for 300, 350, and 400 kg/m3 at 0.45 of a free water cement ratio. The influence of frosting damage on the rate of chloride transport was assessed by testing with concrete specimens subjected to a rapid freezing and thawing cyclic environment. As a result, it was found that chloride transport was accelerated by frost damage, which was more influential at the lower cement content. The microscopic examination of the pore structure showed that the freezing environment increased the volume of the large capillary pore in the concrete matrix.

  8. RNA quality and gene expression analysis of ovarian tumor tissue undergoing repeated thaw-freezing

    DEFF Research Database (Denmark)

    Jochumsen, Kirsten Marie; Tan, Qihua; Dahlgaard, Jesper

    2007-01-01

    unsupervised, and supervised multivariate statistical methods, reliability analysis, as well as verification using published gene lists in ovarian cancer studies. RNA quality and quantity did not change during the division procedure and microarray data showed insignificant difference in gene expression. Tumor......Gene expression profiles evaluated by microarray-based quantization of RNA are used in studies of differential diagnosis and prognosis in cancer. RNA of good quality is mandatory for this evaluation. The RNA most often comes from tumor banks with limited amount of tissue, and the tissue often...... undergoes repeated thawing and freezing. We evaluated the influence of repeated division of tumor samples at room temperature, on RNA quality and quantity, in addition to the gene expression profile. Sixteen ovarian tumor samples were divided in three aliquots each, undergoing respectively one, two...

  9. Freeze/thaw-induced embolism: probability of critical bubble formation depends on speed of ice formation

    Directory of Open Access Journals (Sweden)

    Sanna eSevanto

    2012-06-01

    Full Text Available Bubble formation in the conduits of woody plants sets a challenge for uninterrupted water transportation from the soil up to the canopy. Freezing and thawing of stems has been shown to increase the number of air-filled (embolized conduits, especially in trees with large conduit diameters. Despite numerous experimental studies, the mechanisms leading to bubble formation during freezing have not been addressed theoretically. We used classical nucleation theory and fluid mechanics to show which mechanisms are most likely to be responsible for bubble formation during freezing and what parameters determine the likelihood of the process. Our results confirm the common assumption that bubble formation during freezing is most likely due to gas segregation by ice. If xylem conduit walls are not permeable to the salts expelled by ice during the freezing process, osmotic pressures high enough for air seeding could be created. The build-up rate of segregated solutes in front of the ice-water interface depends equally on conduit diameter and freezing velocity. Therefore, bubble formation probability depends on these variables. The dependence of bubble formation probability on freezing velocity means that the experimental results obtained for cavitation threshold conduit diameters during freeze/thaw cycles depend on the experimental setup; namely sample size and cooling rate. The velocity dependence also suggests that to avoid bubble formation during freezing trees should have narrow conduits where freezing is likely to be fast (e.g. branches or outermost layer of the xylem. Avoidance of bubble formation during freezing could thus be one piece of the explanation why xylem conduit size of temperate and boreal zone trees varies quite systematically.

  10. [Cryobiology and pathologic lesions induced by freezing-thawing processes in prostatic tissue. Second part].

    Science.gov (United States)

    Escudero Barrilero, Angel; Arias Fúnez, Fernando; Patrón Rodríguez, Rafael Rodríguez; García González, Ricardo; Cuesta Roca, Carmen

    2004-12-01

    Cryosurgery is an emerging technology consisting on controlled freezing of tissues. Good results, maintained in the long-term, have been referred in the treatment of prostate adenocarcinoma. A role as possible substitute of partial nephrectomy in the treatment of renal adenocarcinomas smaller than 4-5 cm is under research. There is no discussion that freezing destroys cellular machinery and triggers several events the final result of which is cell death by necrosis and apoptosis. The decrease of temperature makes extracellular liquid crystallize and creates a hyperosmotic environment, which induces water to go out of the cell producing intracellular dehydration. Intracellular ice is created with fast freezing speeds being attributed the most destructive effect on biological tissues with irreparable damage. In blood vessels, it directly induces endothelial cell death and mechanical lesions of the endothelium; the consequence is the formation of thrombi that obstruct the lumen of the vessel. In the post-thawing phase there is an increase in free radicals formation and neutrophil activity, which induces cellular membrane lipids peroxidation and new endothelium lesions. Tissue destruction is determined by: minimal temperature achieved, freezing speeds, freezing phase duration, number of freezing-thawing cycles provided, and distance to the freezing focus. As we move away from the freezing focus cells are affected in different ways, and there are several mechanisms proposed to explain the lethal action induced by temperatures higher than--40 degrees C. In our series pathologic findings were: necrosis, hemorrhagic areas either developed or not, fibrosis, hyalinization and increases in the relative number of hematic capillaries, microscopic calcifications, basal cells hyperplasia, and transitional or squamous metaplasia. Residual cancer is localized in the areas less affected by freezing. It should be emphasize the scarce morbimortality associated with the procedure. It

  11. Behavior of the plasma membrane of isolated protoplasts during a freeze-thaw cycle

    Energy Technology Data Exchange (ETDEWEB)

    Dowgert, M.F.; Steponkus, P.L.

    1984-08-01

    Cryomicroscopy of protoplasts isolated from nonacclimated (NA) rye leaves (Secale cereale L. cv Puma) revealed that the predominant form of injury following cooling to the minimum temperature for 50% survival (LT/sub 50/) (-5/sup 0/C) was expansion-induced lysis of the plasma membrane during warming and thawing of the suspending medium when the decreasing osmolality resulted in osmotic expansion of the protoplasts. When cooled to temperatures below the LT/sub 50/, the predominant form of injury was loss of osmotic responsiveness following cooling so that the protoplasts were osmotically inactive during warming. Only a low incidence (< 10%) of expansion-induced lysis was observed in protoplasts isolated from acclimated (ACC) leaves, and the predominant form of injury following cooling to the LT/sub 50/ (-25/sup 0/C) was loss of osmotic responsiveness. The tolerable surface area increment (TSAI/sub 50/) which resulted in lysis of 50% of a population (TSAI) of NA protoplasts osmotically expanded from isotonic solutions was 1122 +/- 172 square micrometers. Similar values were obtained when the protoplasts were osmotically expanded from hypertonic solutions. Osmotic contractions were readily reversible upon return to isotonic solutions. During freeze-induced dehydration, endocytotic vesicles formed in NA protoplasts whereas exocytotic extrusions formed on the surface of ACC protoplasts. During osmotic expansion following thawing of the suspending medium, the endocytotic vesicles remained in the cytoplasm of NA protoplasts and the protoplasts lysed before their original volume and surface area were regained. In contrast, the exocytotic extrusions were drawn back into the surface of ACC protoplasts as the protoplasts regained their original volume and surface area. 25 references, 10 figures, 1 table.

  12. Comet assay on thawed embryos: An optimized technique to evaluate DNA damage in mouse embryos.

    Science.gov (United States)

    Rolland, L; Courbiere, B; Tassistro, V; Sansoni, A; Orsière, T; Liu, W; Di Giorgio, C; Perrin, J

    2017-10-01

    Our objective was to optimize the CA technique on mammal embryos. 1000 frozen 2-cell embryos from B6CBA mice were used. Based on a literature review, and after checking post-thaw embryo viability, the main outcome measures included: 1) comparison of the embryo recovery rate between 2 CA protocols (2 agarose layers and 3 agarose layers); 2) comparison of DNA damage by the CA on embryos with (ZP+) and without (ZP-) zona pellucida; and 3) comparison of DNA damage in embryos exposed to 2 genotoxic agents (H2O2 and simulated sunlight irradiation (SSI)). DNA damage was quantified by the % tail DNA. 1) The recovery rate was 3,3% (n=5/150) with the 2 agarose layers protocol and 71,3% (n=266/371) with the 3 agarose layers protocol. 2) DNA damage did not differ statistically significantly between ZP- and ZP+ embryos (12.60±2.53% Tail DNA vs 11.04±1.50 (p=0.583) for the control group and 49.23±4.16 vs 41.13±4.31 (p=0.182) for the H2O2 group); 3) H2O2 and SSI induced a statistically significant increase in DNA damage compared with the control group (41.13±4.31% Tail DNA, 36.33±3.02 and 11.04±1.50 (p<0.0001)). The CA on mammal embryos was optimized by using thawed embryos, by avoiding ZP removal and by the adjunction of a third agarose layer. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Bacterial community structure across environmental gradients in permafrost thaw ponds: methanotroph-rich ecosystems

    Science.gov (United States)

    Crevecoeur, Sophie; Vincent, Warwick F.; Comte, Jérôme; Lovejoy, Connie

    2015-01-01

    Permafrost thawing leads to the formation of thermokarst ponds that potentially emit CO2 and CH4 to the atmosphere. In the Nunavik subarctic region (northern Québec, Canada), these numerous, shallow ponds become well-stratified during summer. This creates a physico-chemical gradient of temperature and oxygen, with an upper oxic layer and a bottom low oxygen or anoxic layer. Our objective was to determine the influence of stratification and related limnological and landscape properties on the community structure of potentially active bacteria in these waters. Samples for RNA analysis were taken from ponds in three contrasting valleys across a gradient of permafrost degradation. A total of 1296 operational taxonomic units were identified by high throughput amplicon sequencing, targeting bacterial 16S rRNA that was reverse transcribed to cDNA. β-proteobacteria were the dominant group in all ponds, with highest representation by the genera Variovorax and Polynucleobacter. Methanotrophs were also among the most abundant sequences at most sites. They accounted for up to 27% of the total sequences (median of 4.9% for all samples), indicating the importance of methane as a bacterial energy source in these waters. Both oxygenic (cyanobacteria) and anoxygenic (Chlorobi) phototrophs were also well-represented, the latter in the low oxygen bottom waters. Ordination analyses showed that the communities clustered according to valley and depth, with significant effects attributed to dissolved oxygen, pH, dissolved organic carbon, and total suspended solids. These results indicate that the bacterial assemblages of permafrost thaw ponds are filtered by environmental gradients, and are complex consortia of functionally diverse taxa that likely affect the composition as well as magnitude of greenhouse gas emissions from these abundant waters. PMID:25926816

  14. Hydroxyethyl starch as a substitute for dextran 40 for thawing peripheral blood progenitor cell products.

    Science.gov (United States)

    Zhu, Fenlu; Heditke, Sarah; Kurtzberg, Joanne; Waters-Pick, Barbara; Hari, Parameswaran; Margolis, David A; Keever-Taylor, Carolyn A

    2015-12-01

    Removing DMSO post-thaw results in: reduced infusion reactions, improved recovery and stability of viable CD34+ cells. Validated methods use 5%-8.3% Dextran 40 with 2.5%-4.2% HSA for this purpose. Recent shortages of clinical grade Dextran require identification of suitable alternatives. PBPC were used to compare a standard 2X wash medium of 5 parts 10% Dextran 40 in saline (DEX) with 1 part 25% HSA (8.3% DEX/ 4.2% HSA) with Hydroxyethyl Starch (HES)-based solutions. Cells in replicate bags were diluted with an equal volume of wash solution, equilibrated 5 minutes, the bag filled with wash medium, pelleted and the supernatant expressed. Bags were restored to the frozen volume in wash medium and tested by single platform flow cytometry and CFU. Total viability, viable TNC, MNC, and CD34+ cell recovery, and CD34+ cell viability were compared immediately post-thaw and after 90 minutes. 5.2% HES/4.2% HSA did not differ from our standard in CD34 recovery or viability. Due to concerns that high concentrations of HES could affect renal function we tested 0.6% HES/2.5% HSA resulting in significantly poorer CD34 recovery and viability. Results improved using 2.4% HES/4.2% HSA and when 0.6% HES/4.2%HSA was used no significant differences were seen. CFU assays confirmed no differences between the standard dextran arm and HES at 2.4% or 0.6% so long as HSA was at 4.2%. We conclude that HES from 0.6% to 5.2% with 4.2% HSA is a suitable substitute for Dextran 40 as a reconstitution/washing medium for PBPC products. Copyright © 2015 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.

  15. Present Permafrost Thaw in Central Yakutia, North-East Siberia: Surficial Geology and Hydrology Evidence

    Science.gov (United States)

    Czerniawska, Jolanta; Chlachula, Jiri

    2017-04-01

    Current climate change in the high-latitudes of Eurasia is a generally accepted phenomenon characterized by increased annual temperature values and marked weather anomalies observed in the sub-polar and polar regions. In the northern and NE Siberia, this trend of the MAT rise, documented particularly over the last three decades, is believed to account for the territorial lowland as well as insular mountain frozen ground thaw that in turn has triggered ecosystem feedbacks on the local as well as regional scales. In the northern regions of Yakutia, this is principally witnessed by accelerated near-surface dynamics of seasonally activated de-freezing grounds and inter-linked geomorphic and hydrological actions affecting large-scale tundra landscape settings. In the southern and central taiga-forest areas with perennial alpine and continuous permafrost conditions, respectively, an increased depth of the seasonally melted top-soil layers has become evident accompanied by thermokarst lake expansion and ground surface collapsing. Some cryogenic depressions generated from small gullies over the past decades eloquently demonstrate the intensity and scales of the current permafrost degradation in the Siberian North. The fluvial discharge is most dynamic in late spring to mid-summer because of the cumulative effect of snow-melting because of a high solar radiation and short intervals of torrential rains. Yet, the climate-change-dependent and most active geomorphic agent is the accelerated permafrost thaw seen in landslides and tundra-forest cover decay due to a higher water table. Numerous preserved biotic fossiliferous records Pleistocene and early Holocene in age are being exposed in this process providing unique palaeoecology evidence at particular sites. These climate-generated processes have mostly highly negative effects to the natural habitats (migratory animal routes and riverine biota due to an earlier ice-melting) as well as the local settlement communities

  16. Acceleration of thaw slump activity in glaciated landscapes of the Western Canadian Arctic

    Science.gov (United States)

    Segal, Rebecca A.; Lantz, Trevor C.; Kokelj, Steven V.

    2016-03-01

    Climate change is increasing the frequency and intensity of thermokarst, but the influences of regional climate and physiography remain poorly understood. Retrogressive thaw slumping is one of the most dynamic forms of thermokarst and affects many areas of glaciated terrain across northwestern Canada. In this study, we used airphotos and satellite imagery to investigate the influence of climate and landscape factors on thaw slump dynamics. We assessed slump size, density, and growth rates in four regions of ice-rich terrain with contrasting climate and physiographic conditions: the Jesse Moraine, the Tuktoyaktuk Coastlands, the Bluenose Moraine, and the Peel Plateau. Observed increases in: (1) the area impacted by slumps (+2 to +407%), (2) average slump sizes (+0.31 to +1.82 ha), and (3) slump growth rates (+169 to +465 m2 yr-1) showed that thermokarst activity is rapidly accelerating in ice-rich morainal landscapes in the western Canadian Arctic, where slumping has become a dominant driver of geomorphic change. Differences in slump characteristics among regions indicate that slump development is strongly influenced by topography, ground ice conditions, and Quaternary history. Observed increases in slump activity occurred in conjunction with increases in air temperature and precipitation, but variation in slump activity among the four regions suggests that increased precipitation has been an important driver of change. Our observation that the most rapid intensification of slump activity occurred in the coldest environment (the Jesse Moraine on Banks Island) indicates that ice-cored landscapes in cold permafrost environments are highly vulnerable to climate change.

  17. Freeze/Thaw-Induced Embolism: Probability of Critical Bubble Formation Depends on Speed of Ice Formation

    Science.gov (United States)

    Sevanto, Sanna; Holbrook, N. Michele; Ball, Marilyn C.

    2012-01-01

    Bubble formation in the conduits of woody plants sets a challenge for uninterrupted water transportation from the soil up to the canopy. Freezing and thawing of stems has been shown to increase the number of air-filled (embolized) conduits, especially in trees with large conduit diameters. Despite numerous experimental studies, the mechanisms leading to bubble formation during freezing have not been addressed theoretically. We used classical nucleation theory and fluid mechanics to show which mechanisms are most likely to be responsible for bubble formation during freezing and what parameters determine the likelihood of the process. Our results confirm the common assumption that bubble formation during freezing is most likely due to gas segregation by ice. If xylem conduit walls are not permeable to the salts expelled by ice during the freezing process, osmotic pressures high enough for air seeding could be created. The build-up rate of segregated solutes in front of the ice-water interface depends equally on conduit diameter and freezing velocity. Therefore, bubble formation probability depends on these variables. The dependence of bubble formation probability on freezing velocity means that the experimental results obtained for cavitation threshold conduit diameters during freeze/thaw cycles depend on the experimental setup; namely sample size and cooling rate. The velocity dependence also suggests that to avoid bubble formation during freezing trees should have narrow conduits where freezing is likely to be fast (e.g., branches or outermost layer of the xylem). Avoidance of bubble formation during freezing could thus be one piece of the explanation why xylem conduit size of temperate and boreal zone trees varies quite systematically. PMID:22685446

  18. A single freeze-thawing cycle for highly efficient solubilization of inclusion body proteins and its refolding into bioactive form.

    Science.gov (United States)

    Qi, Xingmei; Sun, Yifan; Xiong, Sidong

    2015-02-22

    Mild solubilization of inclusion bodies has attracted attention in recent days, with an objective to preserve the existing native-like secondary structure of proteins, reduce protein aggregation during refolding and recovering high amount of bioactive proteins from inclusion bodies. Here we presented an efficient method for mild solubilization of inclusion bodies by using a freeze-thawing process in the presence of low concentration of urea. We used two different proteins to demonstrate the advantage of this method over the traditional urea-denatured method: enhanced green fluorescent protein (EGFP) and the catalytic domain of human macrophage metalloelastase (MMP-12_CAT). Firstly, PBS buffer at pH 8 containing different molar concentration of urea (0-8 M) were used to solubilize EGFP and MMP-12-CAT inclusion bodies and the solubility achieved in 2 M urea in PBS buffer by freeze-thawing method was comparable to that of PBS buffer containing 8 M urea by traditional urea-denatured method. Secondly, different solvents were used to solubilize EGFP and MMP-12_CAT from inclusion bodies and the results indicated that a wide range of buffers containing 2 M urea could efficiently solubilize EGFP and MMP-12_CAT inclusion bodies by freeze-thawing method. Thirdly, the effect of pH and freezing temperature on the solubility of EGFP and MMP-12_CAT inclusion bodies were studied, revealing that solubilization of inclusion bodies by freeze-thawing method is pH dependent and the optimal freezing temperature indicated here is -20°C. Forth, the solubilized EGFP and MMP-12_CAT from inclusion bodies were refolded by rapid dilution and dialysis, respectively. The results showed that the refolded efficiency is much higher (more than twice) from freeze-thawing method than the traditional urea-denatured method. The freeze-thawing method containing 2 M urea also effectively solubilized a number of proteins as inclusion bodies in E.coli. Mild solubilization of inclusion body proteins

  19. Potential weathering by freeze-thaw action in alpine rocks in the European Alps during a nine year monitoring period

    Science.gov (United States)

    Kellerer-Pirklbauer, Andreas

    2017-11-01

    A quantification of rock weathering by freeze-thaw processes in alpine rocks requires at least rock temperature data in high temporal resolution, in high quality, and over a sufficient period of time. In this study up to nine years of rock temperature data (2006-2015) from eleven rock monitoring sites in two of the highest mountain ranges of Austria were analyzed. Data were recorded at a half-hourly or hourly logging interval and at rock depths of 3, 10, and 30-40 cm. These data have been used to quantify mean conditions, ranges, and relationships of the potential near-surface weathering by freeze-thaw action considering volumetric-expansion of ice and ice segregation. For the former, freeze-thaw cycles and effective freeze-thaw cycles for frost shattering have been considered. For the latter, the intensity and duration of freezing events as well as time within the 'frost cracking window' have been analyzed. Results show that the eleven sites are in rather extreme topoclimatic positions and hence represent some of the highest and coolest parts of Austria and therefore the Eastern Alps. Only four sites are presumably affected by permafrost. Most sites are influenced by a long-lasting seasonal snow cover. Freeze-thaw cycles and effective freeze-thaw cycles for frost shattering are mainly affecting the near-surface and are unimportant at few tens of centimeters below the rock surface. The lowest temperatures during freezing events and the shortest freezing events have been quantified at all eleven monitoring sites very close to the surface. The time within the frost cracking window decreases in most cases from the rock surface inwards apart from very cold years/sites with very low temperatures close to the surface. As shown by this study and predicted climate change scenarios, assumed warmer rock temperature conditions in the future at alpine rock walls in Austria will lead to less severe freezing events and to shorter time periods within the frost-cracking window

  20. Effects of freezing-thawing on DNA integrity of boar spermatozoa assessed by the neutral comet assay.

    Science.gov (United States)

    Fraser, L; Strzezek, J

    2005-12-01

    A modified version of the neutral comet assay was employed to evaluate the effect of the freezing-thawing process on boar-sperm DNA integrity. The sperm-rich fractions were collected from four mature boars and frozen into aluminium tubes and straws after extension in lactose-hen egg yolk-glycerol extender (lactose-HEY-G) or an extender containing lactose, lyophilized lipoprotein fractions extracted from ostrich egg yolk and glycerol (lactose-LPFo-G). The semen samples were also frozen in a standard boar semen extender (Kortowo-3), without the addition of cryoprotective substances. Post-thaw sperm motility and plasma membrane integrity, assessed by SYBR-14/PI and Hoechst 33258 stains, declined (p sperm DNA damage, regardless of the extender type and packaging material. Spermatozoa frozen in lactose-HEY-G or lactose-LPFo-G extender showed lower (p sperm DNA, which varied among the boars. Inter-boar variations in post-thaw DNA damage were more pronounced in sperm samples frozen in lactose-HEY-G or lactose-LPFo-G extender. The results of this study show that the freezing-thawing process affects the DNA integrity of boar spermatozoa, irrespective of the extender type and packaging material. Furthermore, the use of whole hen egg yolk and ostrich lyophilized lipoprotein fractions in the freezing extender gave similar results regarding sperm DNA integrity. It can be concluded that the neutral comet assay can be used in conjunction with routine sperm parameters for assessment of post-thaw quality of boar semen.

  1. Thaw depth spatial and temporal variability at the Limnopolar Lake CALM-S site, Byers Peninsula, Livingston Island, Antarctica.

    Science.gov (United States)

    de Pablo, M A; Ramos, M; Molina, A; Prieto, M

    2018-02-15

    A new Circumpolar Active Layer Monitoring (CALM) site was established in 2009 at the Limnopolar Lake watershed in Byers Peninsula, Livingston Island, Antarctica, to provide a node in the western Antarctic Peninsula, one of the regions that recorded the highest air temperature increase in the planet during the last decades. The first detailed analysis of the temporal and spatial evolution of the thaw depth at the Limnopolar Lake CALM-S site is presented here, after eight years of monitoring. The average values range between 48 and 29cm, decreasing at a ratio of 16cm/decade. The annual thaw depth observations in the 100×100 m CALM grid are variable (Variability Index of 34 to 51%), although both the Variance Coefficient and the Climate Matrix Analysis Residual point to the internal consistency of the data. Those differences could be explained then by the terrain complexity and node-specific variability due to the ground properties. The interannual variability was about 60% during 2009-2012, increasing to 124% due to the presence of snow in 2013, 2015 and 2016. The snow has been proposed here as one of the most important factors controlling the spatial variability of ground thaw depth, since its values correlate with the snow thickness but also with the ground surface temperature and unconfined compression resistance, as measured in 2010. The topography explains the thaw depth spatial distribution pattern, being related to snowmelt water and its accumulation in low-elevation areas (downslope-flow). Patterned grounds and other surface features correlate well with high thaw depth patterns as well. The edaphic factor (E=0.05842m2/°C·day; R2=0.63) is in agreement with other permafrost environments, since frozen index (F>0.67) and MAAT (CALM sites. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Vitamin E-analog Trolox prevents endoplasmic reticulum stress in frozen-thawed ovarian tissue of capuchin monkey (Sapajus apella).

    Science.gov (United States)

    Brito, D C; Brito, A B; Scalercio, S R R A; Percário, S; Miranda, M S; Rocha, R M; Diniz, J A P; Oskam, I C; Van den Hurk, R; Paris, M C J; Domingues, S F S; Santos, R R

    2014-02-01

    Ovarian fragments were exposed to 0.5 M sucrose and 1 M ethylene glycol (freezing solution; FS) with or without selenium or Trolox. Histological and ultrastructural analyses showed that the percentages of normal follicles in control tissue and in tissue after exposure to FS + 50 μM Trolox were similar. Trolox prevented endoplasmic reticulum (ER)-related vacuolization, which is commonly observed in oocytes and stromal tissue after exposure to FS. From the evaluated stress markers, superoxide dismutase 1 (SOD1) was up-regulated in ovarian tissue exposed to FS + 10 ng/ml selenium. Ovarian fragments were subsequently frozen-thawed in the presence of FS with or without 50 μM Trolox, followed by in vitro culture (IVC). Antioxidant capacity in ovarian fragments decreased after freeze-thawing in Trolox-free FS compared with FS + 50 μM Trolox. Although freezing itself minimized the percentage of viable follicles in each solution, Trolox supplementation resulted in higher rates of viable follicles (67 %), even after IVC (61 %). Furthermore, stress markers SOD1 and ERp29 were up-regulated in ovarian tissue frozen-thawed in Trolox-free medium. Relative mRNA expression of growth factors markers was evaluated after freeze-thawing followed by IVC. BMP4, BMP5, CTGF, GDF9 and KL were down-regulated independently of the presence of Trolox in FS but down-regulation was less pronounced in the presence of Trolox. Thus, medium supplementation with 50 μM Trolox prevents ER stress and, consequently, protects ovarian tissue from ER-derived cytoplasmic vacuolization. ERp29 but not ERp60, appears to be a key marker linking stress caused by freezing-thawing and cell vacuolization.

  3. Supplementation of soybean lecithin-based semen extender by antioxidants: complementary flowcytometric study on post-thawed ram spermatozoa.

    Science.gov (United States)

    Sharafi, Mohsen; Zhandi, Mahdi; Akbari Sharif, Abbas

    2015-06-01

    The purpose of the current study was to evaluate the effects of cysteine (C) and glutathione (G) on the post-thawed ram sperm quality. Collected semen samples from four mature rams were diluted with five soybean lecithin (SL)-based extenders containing: no antioxidant (SL-0), 5 mM cysteine (SL-C5), 10 mM cysteine (SL-C10), 5 mM glutathione (SL-G5) and 10 mM glutathione (SL-G10). After freeze-thawing process, motion and velocity parameters, plasma membrane integrity and functionality, morphological abnormality, lipid peroxidation, acrosomal status, mitochondria activity, and apoptosis status of post-thawed ram spermatozoa were assessed. The results showed that SL-C10 increased the total motility and plasma membrane integrity (p < 0.05) of post-thawed ram spermatozoa (55.86 ± 1.37 and 60.57 ± 1.34 %) compared to other extenders. Progressive motility was significantly higher in SL-C10 (24.71 ± 1.13 %) compared to SL-0 (20 ± 1.13 %) and SL-G10 (15 ± 1.13 %). Mitochondrial activity was significantly higher in SL-C10 (56.83 ± 2.29 %) compared to SL-G10 (38.75 ± 2.29 %). Capacitation and acrosomal status, lipid peroxidation, and the percentage of dead spermatozoa were not affected by different extenders. The percentage of live spermatozoa was higher in SL-C10 (56.33 ± 1.35 %) compared to other extenders. Also, SL-C10 resulted in a lower percentage of apoptotic spermatozoa (14.17 ± 0.53 %) compared to other extenders. The results of this study showed that supplementation of SL-based ram semen extender with 10 mM cysteine resulted in an improved quality of post-thawed ram spermatozoa.

  4. Shallow soil moisture – ground thaw interactions and controls – Part 2: Influences of water and energy fluxes

    Directory of Open Access Journals (Sweden)

    X. J. Guan

    2010-07-01

    Full Text Available The companion paper (Guan et al., 2010 demonstrated variable interactions and correlations between shallow soil moisture and ground thaw in soil filled areas along a wetness spectrum in a subarctic Canadian Precambrian Shield landscape. From wetter to drier, these included a wetland, peatland and soil filled valley. Herein, water and energy fluxes were examined for these same subarctic study sites to discern the key controlling processes on the found patterns. Results showed the presence of surface water was the key control in variable soil moisture and frost table interactions among sites. At the peatland and wetland sites, accumulated water in depressions and flow paths maintained soil moisture for a longer duration than at the hummock tops. These wet areas were often locations of deepest thaw depth due to the transfer of latent heat accompanying lateral surface runoff. Although the peatland and wetland sites had large inundation extent, modified Péclet numbers indicated the relative influence of external and internal hydrological and energy processes at each site were different. Continuous inflow from an upstream lake into the wetland site caused advective and conductive thermal energies to be of equal importance to ground thaw. The absence of continuous surface flow at the peatland and valley sites led to dominance of conductive thermal energy over advective energy for ground thaw. The results suggest that the modified Péclet number could be a very useful parameter to differentiate landscape components in modeling frost table heterogeneity. The calculated water and energy fluxes, and the modified Péclet number provide quantitative explanations for the shallow soil moisture-ground thaw patterns by linking them with hydrological processes and hillslope storage capacity.

  5. Potential rates of anaerobic decomposition and experimental priming effects in thawed peats from discontinuous permafrost in western Canada

    Science.gov (United States)

    Estop Aragones, C.; Heffernan, L.; Olefeldt, D.

    2016-12-01

    Recent climate change has led to increased rates of warming and wildfire in the circumpolar region. It is predicted that this will promote the widespread thawing of permafrost and the development of thermokarst bogs in the peatlands of western Canada. Previously frozen deep organic matter becomes available to microbial activity with thermokarst with the potential loss of C stocks while liberating greenhouse gases to the atmosphere and creating a positive feedback to climate change. Although anoxic conditions in these waterlogged systems may reduce peat decomposition, fresh plant derived C inputs associated with high vegetation productivity post-thaw could increase peat decomposition. The effect of this potential mechanism on enhanced peat decomposition is poorly investigated though. We are measuring anaerobic CO2 and CH4 production rates from a peat plateau, an adjacent young and an old thermokarst feature in the discontinuous permafrost. Samples were selected from depths where peat has been exposed to seasonal thaw (active layer) and from deeper, previously frozen organic matter along 5 m profiles. Preliminary results indicate that most CO2 production is driven by the top meter of peat, especially in the recent thermokarst where the highest rates of CH4 production are also measured due to high vegetation productivity post-thaw. Data suggests that the decomposition of deeper peat is more temperature sensitive. We are considering a 13C labelling experiment to investigate the priming effects on heterotrophic respiration of organic matter heterotrophic respiration once the labile C pool has been depleted and production rates have become stable over time. Fourier transform infrared (FTIR) spectroscopy will be used to determine how peat quality is related to anaerobic decomposition rates, its temperature dependency, and priming effects. These measurements aim to constrain the fate of C through anaerobic decomposition upon permafrost thaw.

  6. Effect of thaw depth on fluxes of CO₂ and CH₄ in manipulated Arctic coastal tundra of Barrow, Alaska.

    Science.gov (United States)

    Kim, Yongwon

    2015-02-01

    Changes in CO₂ and CH₄ emissions represent one of the most significant consequences of drastic climate change in the Arctic, by way of thawing permafrost, a deepened active layer, and decline of thermokarst lakes in the Arctic. This study conducted flux-measurements of CO₂ and CH₄, as well as environmental factors such as temperature, moisture, and thaw depth, as part of a water table manipulation experiment in the Arctic coastal plain tundra of Barrow, Alaska during autumn. The manipulation treatment consisted of draining, controlling, and flooding treated sections by adjusting standing water. Inundation increased CH₄ emission by a factor of 4.3 compared to non-flooded sections. This may be due to the decomposition of organic matter under a limited oxygen environment by saturated standing water. On the other hand, CO₂ emission in the dry section was 3.9-fold higher than in others. CH₄ emission tends to increase with deeper thaw depth, which strongly depends on the water table; however, CO₂ emission is not related to thaw depth. Quotients of global warming potential (GWPCO₂) (dry/control) and GWPCH₄ (wet/control) increased by 464 and 148%, respectively, and GWPCH₄ (dry/control) declined by 66%. This suggests that CO₂ emission in a drained section is enhanced by soil and ecosystem respiration, and CH₄ emission in a flooded area is likely stimulated under an anoxic environment by inundated standing water. The findings of this manipulation experiment during the autumn period demonstrate the different production processes of CO₂ and CH₄, as well as different global warming potentials, coupled with change in thaw depth. Thus the outcomes imply that the expansion of tundra lakes leads the enhancement of CH₄ release, and the disappearance of the lakes causes the stimulated CO₂ production in response to the Arctic climate change. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Characterization of Propylene Glycol-Mitigated Freeze/Thaw Agglomeration of a Frozen Liquid nOMV Vaccine Formulation by Static Light Scattering and Micro-Flow Imaging.

    Science.gov (United States)

    Mensch, Christopher D; Davis, Harrison B; Blue, Jeffrey T

    2015-01-01

    The purpose of this work was to investigate the susceptibility of an aluminum adjuvant and an aluminum-adjuvanted native outer membrane vesicle (nOMV) vaccine formulation to freeze/thaw-induced agglomeration using static light scattering and micro-flow Imaging analysis; and to evaluate the use of propylene glycol as a vaccine formulation excipient by which freeze/thaw-induced agglomeration of a nOMV vaccine formulation could be mitigated. Our results indicate that including 7% v/v propylene glycol in an nOMV containing aluminum adjuvanted vaccine formulation, mitigates freeze/thaw-induced agglomeration. We evaluated the effect of freeze-thawing on an aluminum adjuvant and an aluminum adjuvanted native outer membrane vesicle (nOMV) vaccine formulation. Specifically, we characterized the freeze/thaw-induced agglomeration through the use of static light scattering, micro-flow imaging, and cryo-electron microscopy analysis. Further, we evaluated the use of 0-9% v/v propylene glycol as an excipient which could be included in the formulation for the purpose of mitigating the agglomeration induced by freeze/thaw. The results indicate that using 7% v/v propylene glycol as a formulation excipient is effective at mitigating agglomeration of the nOMV vaccine formulation, otherwise induced by freeze-thawing. © PDA, Inc. 2015.

  8. Stability of Thawed Apheresis Fresh-Frozen Plasma Stored for up to 120 Hours at 1°C to 6°C

    Directory of Open Access Journals (Sweden)

    William P. Sheffield

    2016-01-01

    Full Text Available Regulations concerning the storage of transfusable plasma differ internationally. In Canada, plasma obtained from whole blood donations and frozen within 24 hours of phlebotomy (frozen plasma, FP may be thawed and transfused within 120 hours of refrigerated storage. However, plasma frozen within 8 hours of phlebotomy following apheresis donation (FFPA must be transfused within 24 hours of thawing and refrigeration. Our objectives were to measure coagulation factors (F V, VII, and VIII, fibrinogen activities, and the prothrombin time (PT in thawed refrigerated FFPA at 0, 24, and 120 hours of storage and to compare these values to those in thawed refrigerated FP. Fibrinogen activity remained unchanged over time, while mean factor levels in 28 FFPA units declined by 17% (FV, 19.7% (FVII, and 54.6% (FVIII over 120 hours, while PT values rose to 7.6%. Factor activities were significantly higher in FFPA than FP after 120 hours of refrigerated storage. Residual FVIII activities in thawed FFPA met predefined noninferiority criteria compared to thawed FP after 120 hours. These results support a change in Canadian regulations to permit transfusion of thawed FFPA made in a closed system and refrigerated for up to 120 hours, one that could reduce wastage of transfusable plasma.

  9. Climatic variation and seed persistence: freeze-thaw cycles lower survival via the joint action of abiotic stress and fungal pathogens.

    Science.gov (United States)

    Connolly, Brian M; Orrock, John L

    2015-10-01

    Global climate change is altering thermal cycles in soils during late winter, a transition that may directly threaten seed survival via abiotic stress, facilitate infection by soil-borne pathogens, or both. Using field-collected soil and seeds of the perennial bunchgrass Elymus canadensis, we tested the hypothesis that soil freeze-thaw events limit survival within the soil through direct effects on seed persistence and amplification of soil pathogen attack using a factorial experiment that manipulated freeze-thaw cycles (constant freeze vs. freeze-thaw) and fungicide addition. Freeze-thaw treatment resulted in lower seedling emergence and delayed emergence time relative to constant-freeze controls. Fungicide-treated soils had greater emergence relative to untreated soils; the lowest seedling emergence was observed in no-fungicide, freeze-thaw-treated soils (fungi on seeds were mitigated through interactions at the seed-soil interface, as subsequent experiments showed that fungicide and freeze-thaw treatments alone do not influence dormancy. Our work demonstrates that changes in freeze-thaw events directly limit seedling emergence, delay seedling phenology, and provide opportunities for fungal pathogens to limit seed persistence. As recruitment from seeds is a key determinant of plant population dynamics, these results suggest that climatic variation may generate unique consequences for populations under changing climate regimes.

  10. Analysis of prolonged storage on coagulation Factor (F)V, FVII, and FVIII in thawed plasma: is it time to extend the expiration date beyond 5 days?

    Science.gov (United States)

    Tholpady, Ashok; Monson, Janet; Radovancevic, Rajko; Klein, Kimberly; Bracey, Arthur

    2013-03-01

    According to AABB standards, fresh-frozen plasma (FFP) should be thawed at 30 to 37°C and expire after 24 hours. An increase in the aggressive management of trauma patients with thawed plasma has heightened the risk of plasma waste. One way to reduce plasma waste is to extend its shelf life, given that the full range of therapeutic efficacy is maintained. We evaluated the effect of prolonged storage at 1 to 6°C on the activity of Factor (F)V, FVII, and FVIII in plasma thawed at 37 or 45°C. Group O plasma from healthy donors (n=20) was divided into 10 pairs and frozen and stored at not more than -18°C. One sample from each pair was thawed at 37 or 45°C, and all were stored at 1 to 6°C. Samples were analyzed for FV, FVII, and FVIII activity on Days 0, 5, 10, 15, and 20. Plasma thawing time was 17% less at 45°C than at 37°C. No differences were observed between thawing groups in coagulation activity of FV, FVII, and FVIII during the 20-day storage period (p>0.12). In both groups, the activity of FV and FVIII decreased over time but remained within a normal range at 10 days. Although levels of plasma clotting factors are reduced in storage, therapeutic levels of FV and FVIII are maintained in thawed plasma stored for up to 10 days at 1 to 6°C. Thawing of FFP at 45°C decreases thawing time but does not affect the activity of FV, FVII, and FVIII. © 2012 American Association of Blood Banks.

  11. Thawing Permafrost in Arctic Peatlands Leads to Changing Vegetation Composition, Decline in Plant Biodiversity, but Little Change in Biomass

    Science.gov (United States)

    Vining, S. R.; Hough, M.; McClure, A.; Saleska, S. R.; Rich, V. I.

    2016-12-01

    As permafrost thaws over the next century due to a rapidly changing climate, the shifting nature and amount of bioavailable soil organic matter (SOM) are causing ecosystem-level changes in carbon dioxide (CO2) and methane (CH4) fluxes. These greenhouse gases could drive a positive feedback to climate change, increasing the rate of permafrost thaw. The change in SOM is due to (a) new availability of previously frozen permafrost carbon (C), and (b) shifting plant communities. Appreciable study has focused on the former; we focus here on the latter, at a `natural' permafrost thaw gradient in Arctic Abisko, Sweden. As previously frozen soil destabilizes and collapses into a waterlogged habitat, dominant vegetation type shifts from smaller, woodier plants to moss-dominated sites, then to taller, leafier sedges. This plant community succession is associated with increased CO2 uptake, which could partially offset the thaw-associated C release from soils if it resulted in greater C storage. We tested the hypothesis that C stored in plant biomass increases spatially across the thaw gradient by sampling both above and belowground biomass. We also took time points from the early and peak-growing season (early June to late July) to test if differences in plant growth seasonality impacted our biomass measures. Surprisingly, we found that total above and belowground biomass together do not significantly change from the intact to the fully-thawed habitats, despite previous research showing that productivity appears to be higher in the fully water-logged fen. However, biodiversity significantly decreased from the intact to waterlogged sites. The lack of observed biomass increase despite the increase in NPP observed in other studies from this site could be explained if the C taken up by sedges in fen sites is deposited in SOM at increased rates either through root exudates or annual litter deposition. Since the shift in plant community composition is associated with the observed

  12. Elemental composition and optical properties reveal changes in dissolved organic matter along a permafrost thaw chronosequence in a subarctic peatland

    Energy Technology Data Exchange (ETDEWEB)

    Hodgkins, Suzanne; Tfaily, Malak M.; Podgorski, David C.; McCalley, Carmody; Saleska, Scott; Crill, Patrick M.; Rich, Virginia; Chanton, Jeffrey; Cooper, William T.

    2016-08-01

    The fate of carbon stored in permafrost-zone peatlands represents a significant uncertainty in global climate modeling. Given that the breakdown of dissolved organic matter (DOM) is often a major pathway for decomposition in peatlands, knowledge of DOM reactivity under different permafrost regimes is critical for determining future climate feedbacks. To explore the effects of permafrost thaw and resultant plant succession on DOM reactivity, we used a combination of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), UV/Vis absorbance, and excitation-emission matrix spectroscopy (EEMS) to examine the DOM elemental composition and optical properties of 27 pore water samples gathered from various sites along a permafrost thaw sequence in Stordalen Mire, a thawing subarctic peatland in northern Sweden. The presence of dense Sphagnum moss, a feature that is dominant in the intermediate thaw stages, appeared to be the main driver of variation in DOM elemental composition and optical properties at Stordalen. Specifically, DOM from sites with Sphagnum had greater aromaticity, higher average molecular weights, and greater O/C, consistent with a higher abundance of phenolic compounds that likely inhibit decomposition. These compounds are released by Sphagnum and may accumulate due to inhibition of phenol oxidase activity by the acidic pH at these sites. In contrast, sites without Sphagnum, specifically fully-thawed rich fens, had more saturated, more reduced compounds, which were high in N and S. Optical properties at rich fens were indicated the presence of microbially-derived DOM, consistent with the higher decomposition rates previously measured at these sites. These results indicate that Sphagnum acts as an inhibitor of rapid decomposition and CH4 release in thawing subarctic peatlands, consistent with lower rates of CO2 and CH4 production previously observed at these sites. However, this inhibitory effect may disappear if Sphagnumdominated bogs

  13. Modified control strategies for critical source area of nitrogen (CSAN) in a typical freeze-thaw watershed

    Science.gov (United States)

    Wei, Peng; Ouyang, Wei; Gao, Xiang; Hao, Fanghua; Hao, Zengchao; Liu, Hongbin

    2017-08-01

    The management of critical source areas of diffuse nitrogen (CSANs) remains challenging in freeze-thaw areas due to the different N loss characteristics in different hydrological conditions and seasons. To address these challenges, a modified strategy was proposed in this study using the Soil and Water Assessment Tool (SWAT) to simulate diffuse N loads in the study catchments. Specifically, the spatial and temporal variations of CSANs caused by differences in precipitation and seasons were considered. In addition, the selection of best management practices (BMPs) was selected according to BMP performance and their seasonal characteristics in diffuse N control. The diffuse N load formed during freeze-thaw seasons accounts for approximately 50% of the annual diffuse N load. The diffuse N load discharged to rivers was higher in wet conditions than dry conditions by 127.4% and 181.5% during freeze-thaw seasons and growing seasons, respectively. The spatial distribution of CSANs was more sensitive to differences between freeze-thaw and growing seasons. Among BMPs, buffer strips (BS), no tillage (NT) and reducing N fertilizer applications (RNFA) all showed differences in their diffuse N removal efficiency under different hydrological conditions and seasons, while reforestation operations were not affected by these factors. The benefit of reforestation operations was lower in flatter areas. When areas with slopes greater than 2 degrees were reforested, the average N removal efficiency of the 1st CSAN could be as high as 82.4%. In the 2nd CSAN, the average N removal efficiency of BS was relatively constant across freeze-thaw seasons. Across growing seasons, the N removal efficiency of BS in wet years was 8%-10% higher than in dry conditions due to the lower percentage of lateral flow. The average N removal efficiency of NT was higher during freeze-thaw seasons and lower during growing seasons with average values of 9.3% and 6.1%, respectively. The N control efficiency of

  14. Permafrost Thaw, Soil Moisture and Plant Community Change Alter Organic Matter Decomposition in Alaskan Tundra

    Science.gov (United States)

    Natali, S.; Mauritz, M.; Pegoraro, E.; Schuur, E.

    2015-12-01

    Climate warming in arctic tundra has been associated with increased plant productivity and a shift in plant community composition, specifically an increase in shrub cover, which can impact soil organic matter through changes in the size and composition of the leaf litter pool. Shifts in litter quantity and quality will in turn interact with changes in the soil environment as the climate continues to warm. We examined the effects of permafrost thaw, soil moisture changes, and plant community composition on leaf litter decomposition in an upland tundra ecosystem in Interior Alaska. We present warming and drying effects on decomposition rates of graminoid-dominated and shrub-dominated leaf litter mixtures over three years (2 cm depth), and annual decomposition of a common cellulose substrate (0-10 cm and 10-20 cm) over five years at a permafrost thaw and soil drying experiment. We expected that warming and drying would increase decomposition, and that decomposition would be greater in the shrub litter than in the graminoid litter mix. Decomposition of Betula nana, the dominant shrub, was 50% greater in the shrub-dominated litter mix compared to the graminoid-dominated litter. Surprisingly, there was no significant difference in total litter mass loss between graminoid and shrub litter mixtures, despite significant differences in decomposition rates of the dominant plant species when decomposed alone and in community mixtures. Drying decreased decomposition of B. nana and of the shrub community litter overall, but after two years there was no detected warming effect on shrub-community decomposition. In contrast to leaf litter decomposition, both warming and drying increased decomposition of the common substrate. Warming caused an almost twofold increase in cellulose decomposition in surface soil (0-10cm), and drying caused a twofold increase in cellulose decomposition from deeper organic layer soils (10-20cm). These results demonstrate the importance of interactions

  15. Freeze-thaw decellularization of the trabecular meshwork in an ex vivo eye perfusion model

    Directory of Open Access Journals (Sweden)

    Yalong Dang

    2017-08-01

    Full Text Available Objective The trabecular meshwork (TM is the primary substrate of outflow resistance in glaucomatous eyes. Repopulating diseased TM with fresh, functional TM cells might be a viable therapeutic approach. Decellularized TM scaffolds have previously been produced by ablating cells with suicide gene therapy or saponin, which risks incomplete cell removal or dissolution of the extracellular matrix, respectively. We hypothesized that improved trabecular meshwork cell ablation would result from freeze-thaw cycles compared to chemical treatment. Materials and Methods We obtained 24 porcine eyes from a local abattoir, dissected and mounted them in an anterior segment perfusion within two hours of sacrifice. Intraocular pressure (IOP was recorded continuously by a pressure transducer system. After 72 h of IOP stabilization, eight eyes were assigned to freeze-thaw (F ablation (−80 °C × 2, to 0.02% saponin (S treatment, or the control group (C, respectively. The TM was transduced with an eGFP expressing feline immunodeficiency viral (FIV vector and tracked via fluorescent microscopy to confirm ablation. Following treatment, the eyes were perfused with standard tissue culture media for 180 h. TM histology was assessed by hematoxylin and eosin staining. TM viability was evaluated by a calcein AM/propidium iodide (PI assay. The TM extracellular matrix was stained with Picro Sirius Red. We measured IOP and modeled it with a linear mixed effects model using a B-spline function of time with five degrees of freedom. Results F and S experienced a similar IOP reduction of 30% from baseline (P = 0.64. IOP reduction of about 30% occurred in F within 24 h and in S within 48 h. Live visualization of eGFP demonstrated that F conferred a complete ablation of all TM cells and only a partial ablation in S. Histological analysis and Picro Sirius staining confirmed that no TM cells survived in F while the extracellular matrix remained. The viability assay showed

  16. Simulation of permafrost and seasonal thaw depth in the JULES land surface scheme

    Directory of Open Access Journals (Sweden)

    R. Dankers

    2011-09-01

    Full Text Available Land surface models (LSMs need to be able to simulate realistically the dynamics of permafrost and frozen ground. In this paper we evaluate the performance of the LSM JULES (Joint UK Land Environment Simulator, the stand-alone version of the land surface scheme used in Hadley Centre climate models, in simulating the large-scale distribution of surface permafrost. In particular we look at how well the model is able to simulate the seasonal thaw depth or active layer thickness (ALT. We performed a number of experiments driven by observation-based climate datasets. Visually there is a very good agreement between areas with permafrost in JULES and known permafrost distribution in the Northern Hemisphere, and the model captures 97% of the area where the spatial coverage of the permafrost is at least 50%. However, the model overestimates the total extent as it also simulates permafrost where it occurs sporadically or only in isolated patches. Consistent with this we find a cold bias in the simulated soil temperatures, especially in winter. However, when compared with observations on end-of-season thaw depth from around the Arctic, the ALT in JULES is generally too deep. Additional runs at three sites in Alaska demonstrate how uncertainties in the precipitation input affect the simulation of soil temperatures by affecting the thickness of the snowpack and therefore the thermal insulation in winter. In addition, changes in soil moisture content influence the thermodynamics of soil layers close to freezing. We also present results from three experiments in which the standard model setup was modified to improve physical realism of the simulations in permafrost regions. Extending the soil column to a depth of 60 m and adjusting the soil parameters for organic content had relatively little effect on the simulation of permafrost and ALT. A higher vertical resolution improves the simulation of ALT, although a considerable bias still remains. Future model

  17. The role of intergenerational influence in waste education programmes: the THAW project.

    Science.gov (United States)

    Maddox, P; Doran, C; Williams, I D; Kus, M

    2011-12-01

    Whilst the education of young people is often seen as a part of the solution to current environmental problems seeking urgent attention, it is often forgotten that their parents and other household members can also be educated/influenced via home-based educational activities. This paper explores the theory of intergenerational influence in relation to school based waste education. Waste Watch, a UK-based environmental charity (www.wastewatch.org.uk), has pioneered a model that uses practical activities and whole school involvement to promote school based action on waste. This methodology has been adopted nationally. This paper outlines and evaluates how effective school based waste education is in promoting action at a household level. The paper outlines Waste Watch's 'Taking Home Action on Waste (THAW)' project carried out for two and half years in Rotherham, a town in South Yorkshire, England. The project worked with 6705 primary age children in 39 schools (44% of primary schools in the project area) to enable them to take the "reduce, reuse and recycle message" home to their families and to engage these (i.e. families) in sustainable waste management practices. As well as substantial increases in students' knowledge and understanding of waste reduction, measurement of the impact of the project in areas around 12 carefully chosen sample schools showed evidence of increased participation in recycling and recycling tonnages as well as declining levels of residual waste. Following delivery of the project in these areas, an average increase of 8.6% was recorded in recycling set out rates which led to a 4.3% increase in paper recycling tonnages and an 8.7% increase in tonnages of cans, glass and textiles collected for recycling. Correspondingly, there was a 4.5% fall in tonnages of residual waste. Waste Watch's THAW project was the first serious attempt to measure the intergenerational influence of an education programme on behaviour at home (i.e. other than schools

  18. Complementary testing techniques applied to obtain the freeze-thaw resistance of concrete

    Directory of Open Access Journals (Sweden)

    Romero, H. L.

    2015-03-01

    Full Text Available Most of the standards that evaluate the resistance of concrete against freeze-thaw cycles (FTC are based on the loss of weight due to scaling. Such procedures are useful but do not provide information about the microstructural deterioration of the concrete. The test procedure needs to be stopped after several FTCs for weighing the loss of material by scaling. This paper proposes the use of mercury-intrusion-porosimetry and thermogravimetric analysis for assessing the microstructural damage of concrete during FTCs. Continuous strain measurement can be performed without stopping the FTCs. The combination of the above techniques with the freeze-thaw resistance standards provides better and more precise information about concrete damage. The proposed procedure is applied to an ordinary concrete, a concrete with silica fume addition and one with an air-entraining agent. The test results showed that the three techniques used are suitable and useful to be employed as complementary to the standards.Las normas para evaluar la resistencia del hormigón a los ciclos hielo-deshielo (CHD se basan habitualmente en la pérdida de peso por descascarillamiento. Son útiles, pero no proporcionan información sobre el deterioro microestructural del hormigón. Además, exigen detener el ensayo para pesar el material desprendido. Se propone el uso complementario de la porosimetría por intrusión de mercurio y el análisis termogravimétrico para evaluar el daño microestructural del hormigón durante los CHDs. La medida continua de las deformaciones puede hacerse sin detener los CHDs. La combinación de las técnicas enumeradas con las normas de ensayo proporciona información más completa sobre el daño del hormigón. El procedimiento propuesto se aplica a un hormigón convencional, a un hormigón con adición de humo de sílice y a otro con aireante. Los resultados de los ensayos mostraron que las tres técnicas usadas son útiles y adecuadas como complemento a

  19. Fracture energy evolution of two concretes resistant to the action of freeze-thaw cycles

    Directory of Open Access Journals (Sweden)

    Enfedaque, A.

    2014-03-01

    Full Text Available The current standards that regulate use of structural concrete have highlighted the durability of concrete. However, how the fracture energy of concrete evolves under the action of freeze-thaw cycles is not well known. The fracture energy of two types of concrete, one with an air-entraining additive and the other with silica fume addition, is studied after four, 14 and 28 freeze-thaw cycles. The results obtained show that the concrete with an air-entraining additive was undamaged and that fracture energy grew slightly. In addition to this, they also showed that the concrete with silica fume addition suffered severe surface scaling and its fracture energy changed due to the greater fracture areas generated.La actual normativa que rige el empleo de hormigón estructural ha puesto enfásis en la durabilidad del hormigón. Sin embargo, no se conoce cómo evoluciona la energía de fractura del hormigón sometido a ciclos hielo- deshielo, lo cual es de vital importancia para asegurar la durabilidad y el correcto comportamiento mecánico de las estructuras de hormigón en entornos con heladas durante su vida útil. Se ha estudiado la evolución de la energía de fractura de un hormigón con aireante y de un hormigón con humo de sílice después de 4, 14 y 28 ciclos hielo-deshielo realizando ensayos de fractura. Los resultados muestran cómo el hormigón con aireante no sufre daño por los ciclos hielo-deshielo y cómo la energía de fractura del mismo aumenta ligeramente. El hormigón con humo de sílice se daña por los ciclos hielo-deshielo y reduce su energía de fractura al aumentar el area fracturada.

  20. Thermokarst Caves, Baydzherakhs, and Thaw Subsidence, Oh My! Combining Ground Based Geophysics and Survey Measurements With Airborne LiDAR to Understand Rates and Patterns of Rapid Permafrost Thaw

    Science.gov (United States)

    Douglas, T. A.; Hiemstra, C. A.; Bjella, K.

    2016-12-01

    Arctic and sub-Arctic discontinuous permafrost regions are nearing thaw instability. Warming temperatures, human or natural disturbance, altered precipitation, or a shift in the timing of seasonal transitions can lead to dramatic landscape changes on timescales of a few years. Much of the permafrost thaw surface expression is controlled by melting subsurface ice features, and these "hot spot" locations are currently not specifically mapped and are likely increasing in number and areal distribution. Tools are needed to identify where, how, and at what rate thermokarst, thaw subsidence, and altered hydrologic flowpaths develop. Galvanic coupled resistivity tomography (GRT) allows for an indirect qualitative identification of permafrost; frozen versus thawed, and ice-rich versus ice-poor. When GRT is combined with aboveground repeat imagery and LiDAR spatial information, permafrost landscape change can be detected and rates and scales of this change ascertained. This can also be combined with vegetation and ecological measurements to identify how rapidly subsurface changes in permafrost alter hydrologic and biogeochemical cycles. We are combining GRT, borehole mapping, airborne and ground-based LiDAR, and snow, soil, and vegetation measurements at a variety of Interior Alaska locations where permafrost landscapes have been exhibiting rapid change. Our features include an area where hillslope erosion developed subsurface thermokarst caverns meters deep and tens of meters long following intense summer precipitation events. We are studying thermokarst at a 600-m long lake that rapidly drained to expose a field of baydzherakhs meters tall and 5-10 meter across. We have also been monitoring rapid degradation and subsidence in lowland ice rich permafrost. The results from this study suggest the expression of permafrost degradation and thermokarst formation across the landscape are readily apparent and quantifiable. Baseline and recurrent surveying with these coupled

  1. Cumulative live birth rates after one ART cycle including all subsequent frozen-thaw cycles in 1050 women

    DEFF Research Database (Denmark)

    Toftager, M; Bogstad, J; Løssl, K

    2017-01-01

    , subjects were allocated to treatment and 1023 women started standardized ART protocols with recombinant human follitropin-β (rFSH) stimulation. Day-2 SET was planned and additional embryos were frozen and used in subsequent frozen-thawed cycles. All......STUDY QUESTION: Are cumulative live birth rates (CLBRs) similar in GnRH-antagonist and GnRH-agonist protocols for the first ART cycle including all subsequent frozen-thaw cycles from the same oocyte retrieval? SUMMARY ANSWER: The chances of at least one live birth following utilization of all fresh...... and frozen embryos after the first ART cycle are similar in GnRH-antagonist and GnRH-agonist protocols. WHAT IS KNOWN ALREADY: Reproductive outcomes of ART treatment are traditionally reported as pregnancies per cycle or per embryo transfer. However, the primary concern is the overall chance of a live birth...

  2. Rapid yeast DNA extraction by boiling and freeze-thawing without using chemical reagents and DNA purification

    Directory of Open Access Journals (Sweden)

    Gildo Almeida da Silva

    2012-04-01

    Full Text Available The purpose of this work was to study a rapid yeast DNA extraction by boiling and freeze-thawing processes without using chemical reagents or any purification procedures, to obtain a high grade PCR-product. A specific DNA fragment of the 18S region of Dekkera bruxellensis and Saccharomyces cerevisiae was chosen. The described boiling and freeze-thawing protocols generated the PCR-grade product preparations and could be used to process many samples. The amplification of the fragments could be observed after 30 and 35 cycles. These processes of extraction without using any kind of chemical reagents, especial water, and purification procedures proved to be efficient, reproducible, simple, fast, and inexpensive.

  3. Visualization of the freeze/thaw characteristics of a copper/water heat pipe - Effects of non-condensible gas

    Science.gov (United States)

    Ochterbeck, J. M.; Peterson, G. P.

    1991-01-01

    The freeze/thaw characteristics of a copper/water heat pipe of rectangular cross section were investigated experimentally to determine the effect of variations in the amount of non-condensible gases (NCG) present. The transient internal temperature profiles in both the liquid and vapor channels are presented along with contours of the frozen fluid configuration obtained through visual observation. Several interesting phenomena were observed including total blockage of the vapor channel by a solid plug, evaporator dryout during restart, and freezing blowby. In addition, the restart characteristics are shown to be strongly dependent upon the shutdown procedure used prior to freezing, indicating that accurate prediction of the startup or restart characteristics requires a complete thermal history. Finally, the experimental results indicate that the freeze/thaw characteristics of room temperature heat pipes may be significantly different from those occurring in higher temperature, liquid metal heat pipes due to differences in the vapor pressures in the frozen condition.

  4. Modelling and validation of robust partial thawing of frozen convenience foods during distribution in the cold chain

    DEFF Research Database (Denmark)

    Adler-Nissen, Jens; Zammit, Gine Ørnholt

    2011-01-01

    with small blocks of a frozen model food (23 pct. Tylose® gel) and quipped with temperature loggers were distributed by trucks operating in the cold chain. In addition, controlled storage and temperature abuse experiments were conducted. To predict the product temperature–time relationship we developed a new......In collaboration with two commercial distributors we have tested a new concept for distribution, where convenience products for the food service industry are prepared, frozen and packed in cardboard boxes, but distributed in the chill chain at +5°C instead of in the frost chain. This will lead...... thawing model for the slow thawing of food pieces packed in a box. The model is based on enthalpy balances under quasi-stationary conditions; a condition that is fulfilled in the practical distribution experiments. The experiments confirmed the model predictions that the products were still partially...

  5. The Soil Moisture Active Passive (SMAP) Radar: Measurements at High Latitudes and of Surface Freeze/Thaw State

    Science.gov (United States)

    Spencer, Michael; Dunbar, Scott; Chen, Curtis

    2013-01-01

    The Soil Moisture Active/Passive (SMAP) mission is scheduled for a late 2014 launch date. The mission will use both active radar and passive radiometer instruments at L-Band in order to achieve the science objectives of measuring soil moisture and land surface freeze-thaw state. To achieve requirements for a wide swath at sufficiently high resolution for both active and passive channels, an instrument architecture that uses a large rotating reflector is employed. In this paper, focus will be placed on the radar design. The radar will employ synthetic-aperture processing to achieve a "moderate" resolution dual-pol product over a 1000 km swath. Because the radar is operating continuously, very frequent temporal coverage will be achieved at high latitudes. This data will be used to produce a surface freeze/thaw state data product.

  6. Upper subsoil pore characteristics and functions as affected by field traffic and freeze–thaw and dry–wet treatments

    DEFF Research Database (Denmark)

    Schjønning, Per; Lamandé, Mathieu; Cretin, Valentin

    2017-01-01

    depth when the experimental plots had received either 2 years (Flakkebjerg) or 3 years (Aarslev and Taastrup) of repeated compaction treatment. The volume of air-filled pores and air permeability were quantified for soil drained to –100 hPa matric potential. Freeze–thaw and dry–wet treatments were...... not affect the pores and their function. A dry–wet event was a more effective remediation of compaction than a freeze–thaw treatment. In conclusion, present-day field traffic risks creating a bottleneck soil layer for important soil functions just below the tilled topsoil.......Cultivated soils are subject to very high stresses from machinery. This may affect the soil pore system and its processes, soil functions and soil ecosystem services. Compaction experiments were performed on loamy Luvisols at three sites in Denmark: Aarslev, Flakkebjerg and Taastrup. Non...

  7. Stability Evaluation of Volcanic Slope Subjected to Rainfall and Freeze-Thaw Action Based on Field Monitoring

    Directory of Open Access Journals (Sweden)

    Shima Kawamura

    2011-01-01

    Full Text Available Rainfall-induced failures of natural and artificial slopes such as cut slopes, which are subjected to freezing and thawing, have been frequently reported in Hokkaido, Japan. In particular, many failures occur intensively from spring to summer seasons. Despite numerous field studies, explanation of their mechanical behavior based on in situ data has not yet been completely achieved due to the difficulty in grasping failure conditions. This study aims at clarifying the aspects of in-situ volcanic slopes subjected to rainfall and freeze-thaw action. The changes in soil moisture, pore pressure, deformations, and temperatures in the slope were investigated using soil moisture meters, tensiometers, thermocouple sensors, clinometers, settlement gauges, an anemovane, a snow gauge, and a rainfall gauge. The data generated from these measures indicated deformation in the slope examined mainly proceeded during the drainage process according to changes in soil moisture. Based on this data, a prediction method for failures is discussed in detail.

  8. Successful application of the strategy of blastocyst biopsy, vitrification, whole genome amplification, and thawed embryo transfer for preimplantation genetic diagnosis of neurofibromatosis type 1

    Directory of Open Access Journals (Sweden)

    Yi-Lin Chen

    2011-03-01

    Conclusion: We first demonstrate successful application of blastocyst biopsy, vitrification, WGA, and thawed embryo transfer for PGD of a monogenic disease. Vitrification of blastocysts after biopsy permits sufficient time for shipment of samples and operation of molecular diagnosis.

  9. Effect of frozen/thawed embryo transfer on birthweight, macrosomia, and low birthweight rates in US singleton infants.

    Science.gov (United States)

    Litzky, Julia F; Boulet, Sheree L; Esfandiari, Navid; Zhang, Yujia; Kissin, Dmitry M; Theiler, Regan N; Marsit, Carmen J

    2017-12-29

    Singleton infants conceived using assisted reproductive technology have lower average birthweights than naturally conceived infants and are more likely to be born low birthweight (macrosomia (>4000 g) and low birthweight (macrosomia and low birthweight were evaluated using multivariable predicted marginal proportions from logistic regression models. In total, 180,184 singleton, term infants were included, with 55,898 (31.02%) having been conceived from frozen/thawed embryos. Frozen/thawed embryo transfer was associated with, on average, a 142 g increase in birthweight compared with infants born after fresh embryo transfer (P macrosomia following frozen/thawed embryo transfer was greater than that following fresh embryo transfer, but the risk of low birthweight among frozen/thawed embryo transfer infants was significantly decreased in comparison with fresh embryo transfer infants. Copyright © 2018 Elsevier Inc. All rights reserved.

  10. Effects of supplemental conjugated linoleic acids (CLA) on fresh and post-thaw sperm quality of Holstein bulls.

    Science.gov (United States)

    Karimi, R; Towhidi, A; Zeinoaldini, S; Rezayazdi, K; Mousavi, M; Safari, H; Martinez-Pastor, F

    2017-06-01

    This study was designed to investigate the effects of feeding-protected conjugated linoleic acid (CLA) on the semen production and sperm freezability in Holstein bulls. Twelve bulls were randomly assigned to two groups (n = 6 per group). Bulls received the normal diet (control group) or the normal diet top-dressed with 50 g of CLA (treated group) for 10 weeks. The control group received 40 g/day calcium soap of fatty acid. Fresh and post-thaw semen quality was assessed on ejaculates collected at the 0, 4, 6, 8 and 10 week of supplementation. Semen evaluations including sperm concentration, motion characteristics (subjective and computer-assisted), viability (Eosin-Nigrosin), membrane integrity (hypo-osmotic swelling test) and abnormality were conducted. Semen volume, sperm concentration and total sperm output were not affected by dietary treatment (p > .05). The proportion of spermatozoa with abnormal morphology in fresh semen significantly increased (p < .05) in the CLA-fed group compared to control group. Also, in CLA-fed group, the proportion of post-thaw spermatozoa with abnormal morphology at week 10 of trial was significantly higher in CLA than control group (p < .05). Progressive motility tended to be increased in the CLA-fed group, although dietary supplementation did not affect other CASA parameters or viability in fresh and frozen-thawed sperm. In this study, CLA supplementation had little positive effect on fresh or post-thaw sperm quality of Holstein bulls. © 2017 Blackwell Verlag GmbH.

  11. l-Carnitine in rooster semen cryopreservation: Flow cytometric, biochemical and motion findings for frozen-thawed sperm.

    Science.gov (United States)

    Fattah, A; Sharafi, M; Masoudi, R; Shahverdi, A; Esmaeili, V; Najafi, A

    2017-02-01

    Rooster semen cryopreservation is not efficient for artificial insemination in breeder flocks. l-Carnitine (LC) has been evaluated for effectiveness in cryopreservation media on the characteristics of rooster sperm after freeze-thawing. Motility characteristics, membrane functionality, abnormal morphology, apoptotic like changes, mitochondria activity and lipid peroxidation of rooster sperms were assessed after freeze-thawing with different concentrations of LC in Beltsville medium. Semen samples were collected from 12 roosters, twice a week, and diluted in the extenders that contained different concentrations of LC. Supplementation of Beltsevile with 1 and 2 mM LC was found to result in higher total motility (68.2± 1.7% and 69.1± 1.7%, respectively), progressive motility (28.4± 1.6%, 29.8± 1.6%), membrane functionality (76.2± 1.9% and 75.9± 1.9%), viability (58.2 ± 1.1%, 59.1 ± 1.1%) and lower significant of lipid peroxidation (2.53 ± 0.08 nmol/ml, 2.49 ± 0.08 nmol/ml) compared to control group containing no LC. Lower motility, progressive motility, and viability were observed in frozen-thawed sperm in extender containing 8 mM LC (35.8± 1.7%, 9.6± 1.2% and 27.1 ± 1.2%, respectively) compared to control. Morphology and mitochondrial activity were not affected by different concentrations of LC. Our results showed that supplementation of Beltsville extender with 1 and 2 mM LC significantly improved the quality of rooster sperm quality after freeze-thawing. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Sperm distribution and fertilization after unilateral and bilateral laparoscopic artificial insemination with frozen-thawed goat semen.

    Science.gov (United States)

    Anakkul, Nitira; Suwimonteerabutr, Junpen; Tharasanit, Theerawat; Khunmanee, Sarawanee; Diloksumpan, Paweena; Berg, Debra K; Techakumphu, Mongkol

    2014-11-01

    Generally, laparoscopic artificial insemination (LAI) provides a higher success rate than of cervical insemination in goats. However, the sperm distribution after LAI in goats remains unknown, particularly when frozen-thawed semen is used. This study evaluated the distribution of frozen-thawed goat spermatozoa after LAI and compared the effects of sperm numbers and deposition sites (unilateral and bilateral sites) on pregnancy rate. In experiment 1, the frozen-thawed spermatozoa were stained either with CellTracker Green CMFDA (CT-Green) or CellTracker Red CMPTX (CT-Red), and in vitro evaluations of viability and motility were performed. In experiment 2, the labeled spermatozoa were deposited via LAI into the left (CT-Green) and right (CT-Red) uterine horns (n = 4). After ovariohysterectomy (6 hours after insemination), the distributions of green- and red-colored spermatozoa were assessed via tissue section, flushing, and the oviductal contents were also collected. Experiment 3 was designed to test the pregnancy rates in a group of 120 does after LAI using different numbers of spermatozoa (60 and 120 × 10(6) sperm per LAI) and different deposition sites. The results demonstrated that the fluorochromes used in this study did not impair sperm motility or viability. Frozen-thawed goat spermatozoa can migrate transuterinally after LAI, as evidenced by the observations of both CT-Green- and CT-Red-labeled spermatozoa in both uterine horns. Lower numbers of spermatozoa (60 × 10(6)) that are inseminated unilaterally (either ipsilateral or contralateral to the site of ovulation) can efficiently be used for LAI in goats (with a 56.67% pregnancy rate). Copyright © 2014 Elsevier Inc. All rights reserved.

  13. Receptor localization of steroid hormones and drugs: discoveries through the use of thaw-mount and dry-mount autoradiography

    OpenAIRE

    Stumpf, W.E.

    1998-01-01

    The history of receptor autoradiography, its development and applications, testify to the utility of this histochemical technique for localizing radiolabeled hormones and drugs at cellular and subcellular sites of action in intact tissues. Localization of diffusible compounds has been a challenge that was met through the introduction of the "thaw-mount" and "dry-mount" autoradiographic techniques thirty years ago. With this cellular receptor autoradiography, used alone or combined with other ...

  14. Cryopreservation of Carp (Cyprinus carpio L.) Sperm: Impact of Seeding and Freezing Rates on Post-Thaw Outputs.

    Science.gov (United States)

    Boryshpolets, Sergii; Sochorová, Denisa; Rodina, Marek; Linhart, Otomar; Dzyuba, Borys

    2017-06-01

    In the present study, we examined various freezing protocols, effects of controlled seeding, and changes in cooling rate and determined the endpoint (temperature at which sample could be plugged into liquid nitrogen (LN) without visible effect on survival rate after thawing) to reveal the relative importance of each different stage of cooling on freezing success during cryobanking of carp sperm. Sperm samples from different individual carp males were frozen in 0.5 mL straws by conventional freezing. Cooling rates were determined by monitoring the sample's internal temperature. We compared four freezing protocols, which involved placing sperm samples at various levels (1, 3, 6, and 9 cm) above the LN surface (corresponding to -190°C, -150°C, -110°C, and -70°C, respectively) for 20 minutes followed by transferring the samples into LN. Freezing at 3 cm above the LN surface resulted in the highest motility (33% ± 8%) and velocity (118 ± 9 μm/s) of spermatozoa after thawing and diluting in swimming medium. We determined that -90°C is an optimal temperature at which immersing the samples in LN does not affect sperm motility after thawing and shorten the process of freezing for around three times. Motility of spermatozoa cryopreserved with or without a seeding procedure was not significantly different after thawing. Therefore, we hypothesize that supercooling the sample during the conventional freezing procedure is not the main damaging factor during carp spermatozoa cryopreservation. However, the cooling rate itself is important, because it determines the ability of the sperm to dehydrate and survive cryopreservation.

  15. Thousands of Viral Populations Recovered from Peatland Soil Metagenomes Reveal Viral Impacts on Carbon Cycling in Thawing Permafrost

    Science.gov (United States)

    Emerson, J. B.; Brum, J. R.; Roux, S.; Bolduc, B.; Woodcroft, B. J.; Singleton, C. M.; Boyd, J. A.; Hodgkins, S. B.; Wilson, R.; Trubl, G. G.; Jang, H. B.; Crill, P. M.; Chanton, J.; Saleska, S. R.; Rich, V. I.; Tyson, G. W.; Sullivan, M. B.

    2016-12-01

    Methane and carbon dioxide emissions, which are under significant microbial control, provide positive feedbacks to climate change in thawing permafrost peatlands. Although viruses in marine systems have been shown to impact microbial ecology and biogeochemical cycling through host cell lysis, horizontal gene transfer, and auxiliary metabolic gene expression, viral ecology in permafrost and other soils remains virtually unstudied due to methodological challenges. Here, we identified viral sequences in 208 assembled bulk soil metagenomes derived from a permafrost thaw gradient in Stordalen Mire, northern Sweden, from 2010-2012. 2,048 viral populations were recovered, which genome- and network-based classification revealed to be largely novel, increasing known viral genera globally by 40%. Ecologically, viral communities differed significantly across the thaw gradient and by soil depth. Co-occurring microbial community composition, soil moisture, and pH were predictors of viral community composition, indicative of biological and biogeochemical feedbacks as permafrost thaws. Host prediction—achieved through clustered regularly interspaced short palindromic repeats (CRISPRs), tetranucleotide frequency patterns, and other sequence similarities to binned microbial population genomes—was able to link 38% of the viral populations to a microbial host. 5% of the implicated hosts were archaea, predominantly methanogens and ammonia-oxidizing Nitrososphaera, 45% were Acidobacteria or Verrucomicrobia (mostly predicted heterotrophic complex carbon degraders), and 21% were Proteobacteria, including methane oxidizers. Recovered viral genome fragments also contained auxiliary metabolic genes involved in carbon and nitrogen cycling. Together, these data reveal multiple levels of previously unknown viral contributions to biogeochemical cycling, including to carbon gas emissions, in peatland soils undergoing and contributing to climate change. This work represents a significant step

  16. Controls on permafrost thaw in a coupled groundwater-flow and heat-transport system: Iqaluit Airport, Nunavut, Canada

    Science.gov (United States)

    Shojae Ghias, Masoumeh; Therrien, René; Molson, John; Lemieux, Jean-Michel

    2017-05-01

    Numerical simulations of groundwater flow and heat transport are used to provide insight into the interaction between shallow groundwater flow and thermal dynamics related to permafrost thaw and thaw settlement at the Iqaluit Airport taxiway, Nunavut, Canada. A conceptual model is first developed for the site and a corresponding two-dimensional numerical model is calibrated to the observed ground temperatures. Future climate-warming impacts on the thermal regime and flow system are then simulated based on climate scenarios proposed by the Intergovernmental Panel on Climate Change (IPCC). Under climate warming, surface snow cover is identified as the leading factor affecting permafrost degradation, including its role in increasing the sensitivity of permafrost degradation to changes in various hydrogeological factors. In this case, advective heat transport plays a relatively minor, but non-negligible, role compared to conductive heat transport, due to the significant extent of low-permeability soil close to surface. Conductive heat transport, which is strongly affected by the surface snow layer, controls the release of unfrozen water and the depth of the active layer as well as the magnitude of thaw settlement and frost heave. Under the warmest climate-warming scenario with an average annual temperature increase of 3.23 °C for the period of 2011-2100, the simulations suggest that the maximum depth of the active layer will increase from 2 m in 2012 to 8.8 m in 2100 and, over the same time period, thaw settlement along the airport taxiway will increase from 0.11 m to at least 0.17 m.

  17. Live birth in a woman without ovaries after autograft of frozen-thawed ovarian tissue combined with growth factors

    OpenAIRE

    Callejo, Justo; Salvador, Cristina; Gonz?lez-Nu?ez, Santiago; Almeida, Laura; Rodriguez, Luciano; Marqu?s, Laura; Valls, Ana; Lailla, Jos? Maria

    2013-01-01

    Currently, cryopreservation of oocytes, embryos and ovarian tissue is considered the basis of fertility preservation programs for women with cancer and other diseases who are rendered sterile by gonadotoxic drugs or radiation. Numerous studies have confirmed that autograft of frozen-thawed ovarian tissue can restore ovarian function and fertility. A total of twenty-two live births have been reported but we still have to consider this technique as experimental. The main problem is that the imp...

  18. Freeze/Thaw Detection in Permafrost Region with C-Band Scatterometers

    Science.gov (United States)

    Naeimi, Vahid; Paulik, Christoph; Wagner, Wolfgang; Barsch, Annett

    2011-01-01

    Distribution of permafrost is largely controlled by climatic conditions. Current permafrost monitoring methods are based on in-situ measurements and modeling and they are mostly local measurements which offer only limited insight in the impacts of global climate variations on the regional to global scale. Permafrost is a subsurface phenomenon which cannot be directly measured with remotely sensed data. But the spatial distribution, thickness and temperature of permafrost is highly dependent on the condition of the active layer overlaying the permafrost. Satellite data can be utilized for operational monitoring of the permafrost active layer by means of a number of indicators and parameters, which are highly valuable for permafrost modeling and monitoring. In this study we present the usage of backscatter measurements from ASCAT scatterometer onboard Metop for detection of freeze/thaw conditions in high latitudes and validate the results with synoptic meteorological measurements. It is shown that there is a high correlation between frozen/unfrozen flag extracted from ASCAT data and the in-situ air temperature measurements.

  19. Estimation Model of Soil Freeze-Thaw Erosion in Silingco Watershed Wetland of Northern Tibet

    Directory of Open Access Journals (Sweden)

    Bo Kong

    2013-01-01

    Full Text Available The freeze-thaw (FT erosion is a type of soil erosion like water erosion and wind erosion. Limited by many factors, the grading evaluation of soil FT erosion quantities is not well studied. Based on the comprehensive analysis of the evaluation indices of soil FT erosion, we for the first time utilized the sensitivity of microwave remote sensing technology to soil moisture for identification of FT state. We established an estimation model suitable to evaluate the soil FT erosion quantity in Silingco watershed wetland of Northern Tibet using weighted summation method of six impact factors including the annual FT cycle days, average diurnal FT phase-changed water content, average annual precipitation, slope, aspect, and vegetation coverage. Finally, with the support of GIS, we classified soil FT erosion quantity in Silingco watershed wetland. The results showed that soil FT erosion are distributed in broad areas of Silingco watershed wetland. Different soil FT erosions with different intensities have evidently different spatial and geographical distributions.

  20. Does the emulsification procedure influence freezing and thawing of aqueous droplets?

    Science.gov (United States)

    Hauptmann, Astrid; Handle, Karl F.; Baloh, Philipp; Grothe, Hinrich; Loerting, Thomas

    2016-12-01

    Here we investigate the freezing and thawing properties of aqueous solutions in oil emulsions, with a particular focus on investigating the influence of the oil and surfactant and the stirring time of the emulsion. Specifically, we employ optical cryomicroscopy in combination with differential scanning calorimetry to study the phase behavior of emulsified 25 wt. % ammonium sulfate droplets in the temperature range down to 93 K. We conclude that the nucleation temperature does not vary with oil-surfactant combination, that is, homogeneous nucleation is probed. However, incomplete emulsification and non-unimodal size distribution of dispersed droplets very often result in heterogeneous nucleation. This in turn affects the distribution of freeze-concentrated solution and the concentration of the solid ice/ammonium sulfate mixture and, thus, the phase behavior at sub-freezing temperatures. For instance, the formation of letovicite at 183 K critically depends on whether the droplets have frozen heterogeneously or homogeneously. Hence, the emulsification technique can be a very strong technique, but it must be ensured that emulsification is complete, i.e., a unimodal size distribution of droplets near 15 μm has been reached. Furthermore, phase separation within the matrix itself or uptake of water from the air may impede the experiments.

  1. Multiscale model of a freeze–thaw process for tree sap exudation

    Science.gov (United States)

    Graf, Isabell; Ceseri, Maurizio; Stockie, John M.

    2015-01-01

    Sap transport in trees has long fascinated scientists, and a vast literature exists on experimental and modelling studies of trees during the growing season when large negative stem pressures are generated by transpiration from leaves. Much less attention has been paid to winter months when trees are largely dormant but nonetheless continue to exhibit interesting flow behaviour. A prime example is sap exudation, which refers to the peculiar ability of sugar maple (Acer saccharum) and related species to generate positive stem pressure while in a leafless state. Experiments demonstrate that ambient temperatures must oscillate about the freezing point before significantly heightened stem pressures are observed, but the precise causes of exudation remain unresolved. The prevailing hypothesis attributes exudation to a physical process combining freeze–thaw and osmosis, which has some support from experimental studies but remains a subject of active debate. We address this knowledge gap by developing the first mathematical model for exudation, while also introducing several essential modifications to this hypothesis. We derive a multiscale model consisting of a nonlinear system of differential equations governing phase change and transport within wood cells, coupled to a suitably homogenized equation for temperature on the macroscale. Numerical simulations yield stem pressures that are consistent with experiments and provide convincing evidence that a purely physical mechanism is capable of capturing exudation. PMID:26400199

  2. Analytical Method for Differentiation of Chilled and Frozen-Thawed Chicken Meat

    Directory of Open Access Journals (Sweden)

    Ivanova Ivelina

    2014-12-01

    Full Text Available : Chilled and frozen chicken breast and thigh meat were stored at +4±1 oC and - 20±1 oC, respectively. Maillard reaction between ribose and meat proteins of the chicken samples was initiated. The changes in the ribose-induced Maillard reaction rate during chilled and frozen storage of chicken meat were evaluated on the bases of corrected absorbance values (A420* and bovine melanoidin equivalent values (mg BME/g. Application of BME as a measure of ribose-induced Maillard reaction rate enables comparability of the data obtained by different spectrophotometers. It was found that the BME values of chicken meat frozen stored for more than 15 days were significantly (P<0.05 lower than BME values of chilled-stored samples. According to the suggested threshold limit values the chicken thigh and breast meat with BME values lower than 30 mg BME/g and 51 mg BME/g, respectively could be classified as frozen-thawed.

  3. Comparison of neonatal outcomes following progesterone use during ovarian stimulation with frozen-thawed embryo transfer.

    Science.gov (United States)

    Zhu, Xiuxian; Ye, Hongjuan; Fu, Yonglun

    2017-08-10

    Progesterone soft capsules (brand name: Utrogestan) were demonstrated to be an effective oral alternative to prevent premature LH surges both in normal-ovulatory and polycystic ovarian syndrome (PCOS) patients. However, its safety in terms of neonatal outcomes is unclear. To evaluate whether Utrogestan use increase the risk of adverse neonatal outcomes compared with short protocol in patients undergoing IVF/ICSI treatments in combination with frozen-thawed embryo transfer (FET), we performed a retrospective analysis including 1008 FET cycles, with embryos originated from either Utrogestan + hMG protocol (n = 499), or short protocol (n = 509), which led to 546 live-born infants. The neonatal characteristics regarding preterm birth (PTB), low birth weight (LBW), gestational age and mode of delivery were comparable in the two groups. The incidence of live-birth defect was 0.68% (2/293) in the Utrogestan + hMG protocol compared with 0.79% (2/253) in the short protocol. No early neonatal death or intrauterine death were recorded in either group. To date, the data do not indicate an elevated rate of abnormality at birth after progesterone use during ovarian stimulation but further study with larger populations is needed to confirm these results.

  4. Estimation model of soil freeze-thaw erosion in Silingco watershed wetland of Northern Tibet.

    Science.gov (United States)

    Kong, Bo; Yu, Huan

    2013-01-01

    The freeze-thaw (FT) erosion is a type of soil erosion like water erosion and wind erosion. Limited by many factors, the grading evaluation of soil FT erosion quantities is not well studied. Based on the comprehensive analysis of the evaluation indices of soil FT erosion, we for the first time utilized the sensitivity of microwave remote sensing technology to soil moisture for identification of FT state. We established an estimation model suitable to evaluate the soil FT erosion quantity in Silingco watershed wetland of Northern Tibet using weighted summation method of six impact factors including the annual FT cycle days, average diurnal FT phase-changed water content, average annual precipitation, slope, aspect, and vegetation coverage. Finally, with the support of GIS, we classified soil FT erosion quantity in Silingco watershed wetland. The results showed that soil FT erosion are distributed in broad areas of Silingco watershed wetland. Different soil FT erosions with different intensities have evidently different spatial and geographical distributions.

  5. Alpine permafrost thawing during the Medieval Warm Period identified from cryogenic cave carbonates

    Directory of Open Access Journals (Sweden)

    M. Luetscher

    2013-07-01

    Full Text Available Coarse crystalline cryogenic cave carbonates (CCCcoarse dated to the last glacial period are common in central European caves and provide convincing evidence of palaeo-permafrost during this time. Little is known, however, about the exact nature of the environment in which CCCcoarse formed as no modern analogue setting is known. Here, we report the first findings of sub-recent, albeit inactive, CCCcoarse from a cave of the Western Alps which is located in the present-day permafrost zone. The globular shape and the presence of ubiquitous euhedral crystal terminations are comparable to previously reported aggregates from the last glacial period and strongly suggest that these aggregates formed subaqueously in pools lacking agitation. Furthermore, stable isotope values of mm-sized spheroids point to calcite precipitation in a closed system with respect to CO2, strongly supporting the hypothesis of a cryogenic origin associated with the freezing of water ponds. U-series analyses revealed three clusters of late Holocene calcite precipitation intervals between 2129 and 751 a b2k. These ages correlate with known periods of elevated summer temperatures, suggesting that warming and thawing of the frozen catchment above the cave allowed water infiltration into the karst system. The growth of CCCcoarse resulted from the re-freezing of this water in the still cold karst cavities.

  6. Effect of hyaluronic acid-enriched transfer medium on frozen-thawed embryo transfer outcomes.

    Science.gov (United States)

    Fu, Wei; Yu, Min; Zhang, Xiao-Jin

    2018-02-14

    To determine if hyaluronic acid-enriched transfer medium (HETM) affects the implantation rate (IR) and clinical pregnancy rate (PR) in women undergoing frozen-thawed embryo transfer (FET). The records of women who underwent FET from May 2014 to October 2014 were retrospectively reviewed. Outcome measures were IR and PR. In all 1721 cycles of 1632 patients were included in this study. HETM was used for 347 cycles of 342 patients, and standard medium for 1374 cycles of 1290 patients. Overall, FET outcomes were similar between the groups. For patients undergoing their first FET attempt, the IR (24.3% vs 31.6%, P = 0.042) and clinical PR (34.3% vs 50.1%, P = 0.004) were lower in the HETM group. For patients undergoing their second FET attempt, pregnancy outcomes were similar between the groups. For patients undergoing their third or more FET attempt, HETM was associated with a higher IR (33.3% vs 16.4%, P < 0.001) and higher PR (52.2% vs 27.4%, P < 0.001). HETM can improve the embryo IR and clinical PR in patients with repeated implantation failure in the third or more FET attempt. However, the use of HETM for first and second FET should be done with caution. © 2018 Japan Society of Obstetrics and Gynecology.

  7. Aroma improvement by repeated freeze-thaw treatment during Tuber melanosporum fermentation

    Science.gov (United States)

    Xiao, Deng-Rong; Liu, Rui-Sang; He, Long; Li, Hong-Mei; Tang, Ya-Ling; Liang, Xin-Hua; Chen, Tao; Tang, Ya-Jie

    2015-01-01

    The aroma attributes of sulfurous, mushroom and earthy are the most important characteristics of the aroma of Tuber melanosporum. However, these three aroma attributes are absent in the T. melanosporum fermentation system. To improve the quality of the aroma, repeated freeze-thaw treatment (RFTT) was adopted to affect the interplay of volatile organic compounds (VOCs). Using RFTT, not only was the score on the hedonic scale of the aroma increased from the “liked slightly” to the “liked moderately” grade, but the aroma attributes of sulfurous, mushroom and earthy could also be smelled in the T. melanosporum fermentation system for the first time. A total of 29 VOCs were identified, and 9 compounds were identified as the key discriminative volatiles affected by RFTT. Amino acid analysis revealed that methionine, valine, serine, phenylalanine, isoleucine and threonine were the key substrates associated with the biosynthesis of the 9 key discriminative VOCs. This study noted that amino acid metabolism played an important role in the regulation of the aroma of the T. melanosporum fermentation system. PMID:26607288

  8. Immature and mature sperm morphometry in fresh and frozen-thawed falcon ejaculates.

    Science.gov (United States)

    Villaverde-Morcillo, S; Soler, A J; Esteso, M C; Castaño, C; Miñano-Berna, A; Gonzalez, F; Santiago-Moreno, J

    2017-08-01

    Sperm morphometry is one characteristic which may be useful in prediction of fertility and sperm freezability in a species. Knowledge of the sperm characteristics of the ejaculate and the morphometric descriptors is necessary to effectively develop sperm cryopreservation. The aim of the current study was to provide a general description of the sperm from two falcon species (Peregrine falcon Falco peregrinus peregrinus/brookei and Gyrfalcon Falco rusticolus) including immature sperm, sperm head morphometric descriptors, and the existence of mature sperm subpopulations. Semen samples were collected by massage and voluntary false copulation and diluted with Lake and Ravie medium. Smears were prepared of the diluted samples, stained with Hemacolor ® , and subjected to: 1) morphological analysis (bright field optical microscopy), and 2) computerised morphometric analysis; each sperm head was measured for length, width, area and perimeter. In addition, in the Gyrfalcon, pooled semen was frozen in pellets using DMA as a cryoprotectant and the analyses repeated after thawing. The mean percentage of immature sperm (spermatocytes and spermatids) was similarly high in all species/subspecies: Brookei Peregrine falcon (F. p. brookei) 55.5%, European Peregrine falcon (F. p. peregrinus) 65.5% and Gyrfalcon 64.7%. Clustering analyses identified four subpopulations of mature spermatozoa with different morphometric characteristics (P falcon sperm. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Thawing of permafrost may disturb historic cattle burial grounds in East Siberia

    Directory of Open Access Journals (Sweden)

    Boris A. Revich

    2011-11-01

    Full Text Available Climate warming in the Arctic may increase the risk of zoonoses due to expansion of vector habitats, improved chances of vector survival during winter, and permafrost degradation. Monitoring of soil temperatures at Siberian cryology control stations since 1970 showed correlations between air temperatures and the depth of permafrost layer that thawed during summer season. Between 1900s and 1980s, the temperature of surface layer of permafrost increased by 2–4°C; and a further increase of 3°C is expected. Frequent outbreaks of anthrax caused death of 1.5 million deer in Russian North between 1897 and 1925. Anthrax among people or cattle has been reported in 29,000 settlements of the Russian North, including more than 200 Yakutia settlements, which are located near the burial grounds of cattle that died from anthrax. Statistically significant positive trends in annual average temperatures were established in 8 out of 17 administrative districts of Yakutia for which sufficient meteorological data were available. At present, it is not known whether further warming of the permafrost will lead to the release of viable anthrax organisms. Nevertheless, we suggest that it would be prudent to undertake careful monitoring of permafrost conditions in all areas where an anthrax outbreak had occurred in the past.

  10. Concrete Deformations under Simultaneous Impact of Loading and Alternate Freezing and Thawing

    Directory of Open Access Journals (Sweden)

    Goncharov Anatoly

    2017-01-01

    Full Text Available To the best knowledge available today, the creep of concrete is understood as slow plastic deformation caused by continuous external factors. Changes occurring in the structure of concrete are however not discussed. Creep as a phenomenon is typically perceived “in purity”, in an invariable and favorable environment. Evolution of creep deformations thus has a fading character and usually goes along with consolidation of concrete. It is only under loads near the threshold of concrete’s long-term strength that micro-destructions tend to grow during the first phase following application of the load. Creep phenomenon is researched «in pure form», i.e. in constant favorable external conditions. Developing of creep deformations has fading character and accompanied by seal of concrete. In real exploitation conditions of constructions appears changes in temperature and humidity, influencing on development of creep deformation. Alternate freezing and thawing of concrete, which most affects durability, causes in unloaded concrete significant extension deformations. Deformation development under the joint action of loads and alternate freezing and thawingalmost was not researched. In the article presented results of concrete deformation research, differing by frost resistance, under loads in the range from 0,2 to 0,7 of prismatic strength.

  11. Terrain controls on the occurrence of coastal retrogressive thaw slumps along the Yukon Coast, Canada

    Science.gov (United States)

    Ramage, Justine L.; Irrgang, Anna M.; Herzschuh, Ulrike; Morgenstern, Anne; Couture, Nicole; Lantuit, Hugues

    2017-09-01

    Retrogressive thaw slumps (RTSs) are among the most active landforms in the Arctic; their number has increased significantly over the past decades. While processes initiating discrete RTSs are well identified, the major terrain controls on the development of coastal RTSs at a regional scale are not yet defined. Our research reveals the main geomorphic factors that determine the development of RTSs along a 238 km segment of the Yukon Coast, Canada. We (1) show the current extent of RTSs, (2) ascertain the factors controlling their activity and initiation, and (3) explain the spatial differences in the density and areal coverage of RTSs. We mapped and classified 287 RTSs using high-resolution satellite images acquired in 2011. We highlighted the main terrain controls over their development using univariate regression trees model. Coastal geomorphology influenced both the activity and initiation of RTSs: active RTSs and RTSs initiated after 1972 occurred primarily on terrains with slope angles greater than 3.9° and 5.9°, respectively. The density and areal coverage of RTSs were constrained by the volume and thickness of massive ice bodies. Differences in rates of coastal change along the coast did not affect the model. We infer that rates of coastal change averaged over a 39 year period are unable to reflect the complex relationship between RTSs and coastline dynamics. We emphasize the need for large-scale studies of RTSs to evaluate their impact on the ecosystem and to measure their contribution to the global carbon budget.

  12. Increasing viability, numbers, and motility of sperm in men with normal spermatogenesis exposed to saffron extract after freezing- thawing process

    Directory of Open Access Journals (Sweden)

    Y. Khazaei

    2017-04-01

    Full Text Available Background: Sperm freezing method is used frequently in assisted reproductive techniques, on the other hand in different studies negative effect of freezing have been shown on different sperm parameters. Objective: The aim of this study was to determine the effect of saffron extract as an antioxidant, on the different sperm parameters in men with normal spermatogenesis after freezing-thawing process. Methods: In this case-control study, collecting of samples was done in 2015 year from the Infertility Treatment Center, ACECR Branch of Qazvin, Qazvin, Iran. These men had normal spermatogenesis and their spouse had infertility problem. Semen samples was divided in two groups, control without saffron extract, and case with 50 mg/ml saffron extract. Then, samples freezed with snap freezing method. After two weeks, they were thawed and different sperm parameters were assessed. Data were analyzed by two-tail T test. Findings: Our results showed, mean percent of viability (72±0.99, motility (87±0.43, and the number of sperm cells (62.5±3.8 in treaded group was elevated significantly (P0.05. Conclusion: Our results showed that possibly antioxidant agents of saffron extract could scavenge free radicals and thus, optimize different sperm parameters (viability, motility, and number after freezing and thawing.

  13. An abdominal ectopic pregnancy following a frozen-thawed ART cycle: a case report and review of the literature.

    Science.gov (United States)

    Yanaihara, Atsushi; Ohgi, Shirei; Motomura, Kenichirou; Hagiwara, Yuko; Mogami, Tae; Saito, Keisuke; Yanaihara, Takumi

    2017-04-07

    Ectopic pregnancy (EP) occurs in 1% of pregnancies and is reported to be more common in in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) pregnancies. An abdominal ectopic pregnancy (AEP) is a rare form of EP, and there are few reports of an AEP after IVF/ICSI. In this case report, a rare case of AEP after frozen-thawed cycle of ICSI is presented. After a frozen-thawed cycle of ICSI, the beta-human chorionic gonadotropin (HCG) level at 4 weeks 0 days of gestation was 3.4 IU/L. Subsequent dysfunctional uterine bleeding was mistaken for menstruation; however, an AEP of 9 weeks with a fetal heart beat was observed by ultrasound. After the AEP was observed by ultrasound, it was extracted laparoscopically. A rare case of an AEP, which developed after frozen-thawed cycle of ICSI, presented with a very low serum HCG level. Even if the HCG titer is low, follow-up HCG levels and frequent medical examinations are necessary.

  14. Does Platelet-Rich Plasma Freeze-Thawing Influence Growth Factor Release and Their Effects on Chondrocytes and Synoviocytes?

    Directory of Open Access Journals (Sweden)

    Alice Roffi

    2014-01-01

    Full Text Available PRP cryopreservation remains a controversial point. Our purpose was to investigate the effect of freezing/thawing on PRP molecule release, and its effects on the metabolism of chondrocytes and synoviocytes. PRP was prepared from 10 volunteers, and a half volume underwent one freezing/thawing cycle. IL-1β, HGF, PDGF AB/BB, TGF-β1, and VEGF were assayed 1 hour and 7 days after activation. Culture media of chondrocytes and synoviocytes were supplemented with fresh or frozen PRP, and, at 7 days, proliferation, gene expression, and secreted proteins levels were evaluated. Results showed that in the freeze-thawed PRP the immediate and delayed molecule releases were similar or slightly lower than those in fresh PRP. TGF-β1 and PDGF AB/BB concentrations were significantly reduced after freezing both at 1 hour and at 7 days, whereas HGF concentration was significantly lower in frozen PRP at 7 days. In fresh PRP IL-1β and HGF concentrations underwent a significant further increase after 7 days. Similar gene expression was found in chondrocytes cultured with both PRPs, whereas in synoviocytes HGF gene expression was higher in frozen PRP. PRP cryopreservation is a safe procedure, which sufficiently preserves PRP quality and its ability to induce proliferation and the production of ECM components in chondrocytes and synoviocytes.

  15. Surgical recovery and successful surgical transfer of conventionally frozen-thawed embryos in the farmed European polecat (Mustela putorius).

    Science.gov (United States)

    Lindeberg, Heli; Aalto, Jussi; Amstislavsky, Sergei; Piltti, Katja; Järvinen, Mikko; Valtonen, Maija

    2003-11-01

    Surgical transfer of in vivo produced conventionally frozen-thawed embryos of farmed European polecat (Mustela putorius) was investigated as a part of an ex-situ preservation program which has the long-term aim of developing a genome resource bank for the endangered European mink (Mustela lutreola). Eighteen oestrous yearling European polecat donors were mated once daily on two consecutive days using 13 fertile males. The donors were surgically flushed for embryos 8-9 days after the first mating. The embryo recovery rate was 60% (116 embryos/193 corpora lutea). The embryos were cryopreserved with 1.5 M ethylene glycol in a programmable freezer using a conventional slow freezing protocol. The thawed embryos were surgically transferred either after dilution with 0.5 M sucrose or directly without removal of ethylene glycol. To induce ovulation, eight recipient females were mated once daily on two consecutive days with vasectomized males starting 7 or 8 days before embryo transfer. The recipients received 7-11 embryos each and three recipients delivered a total of nine pups after a gestation length of 44-46 days. The embryo survival rate was 10% (9 pups/93 frozen embryos). This report describes the first successful cryopreservation of embryos in the Mustelidae family resulting in viable offspring. The low embryo survival rate, however, indicates that the freezing-thawing protocol needs to be improved.

  16. Ketahanan Susu Kambing Peranakan Ettawah Post-Thawing pada Penyimpanan Lemari Es Ditinjau dari Uji Didih dan Alkohol

    Directory of Open Access Journals (Sweden)

    Andriawino Berdionis Sanam

    2014-01-01

    Full Text Available Penelitian ini bertujuan untuk mengetahui ketahanan dan kerusakan susu kambing peranakan ettawah (PE post-thawing pada penyimpanan lemari es ditinjau dari uji didih dan alkohol. Sampel yang digunakan dalam penelitian ini adalah susu kambing PE yang berasal dari distributor Tuban Kabupaten Badung. Penelitian ini menggunakan Rancangan Acak Kelompok (RAK dengan empat perlakuan yaitu susu kambing PE post-thawing yang disimpan pada suhu 4?C dengan lama penyimpanan jam ke-0, jam ke-4, jam ke-8 dan jam ke-12. Pemeriksaan dilakukan terhadap ketahanan atau kerusakan susu meliputi uji didih dan uji alkohol. Penelitian diulang sebanyak lima kali dengan interval pengambilan sampel setiap hari sekali. Hasil penelitian menunjukkan keadaan susu kambing PE post-thawing pada penyimpanan suhu 4?C ditinjau dari uji didih maupun uji alkohol, masih layak untuk dikonsumsi pada penyimpanan hingga 4. Hal tersebut ditunjukkan dengan kualitas susu masih bagus, sedangkan mulai jam 8 sampai jam 12 hasilnya positif, yang berarti susu sudah tidak layak untuk dikonsumsi. Simpulan yang dapat ditarik adalah susu kambing baik disimpan dalam lemari es selama 4 jam.

  17. Effect of dietary supplementation with omega-3 and -6 on fresh and frozen/thawed sperm quality of dogs

    Directory of Open Access Journals (Sweden)

    Ana Carolina Rodrigues

    2017-10-01

    Full Text Available For years, fatty acids have been recommended as a dietary supplement to improve canine hair. For animal reproduction, supplementation with omegas has been used to increase the reproductive efficiency and conception rate, but few studies have been conducted in dogs. The aim of this study was to evaluate the effects of daily dietary supplementation with omega-3 and -6 on the quality of fresh and frozen/thawed semen in canines. Semen was collected from seven dogs and evaluated for sperm motility, vigor, concentration, and morphology. The 17-week study included 119 ejaculates and was divided according to oral supplementation with omega-3 and -6: M1 (1st-5th week or pre-supplementation; M2 (6th-9th week and M3 (10th-13th week or during supplementation; and M4 (14th-17th week or post-supplementation. After analysis, the semen was frozen and then revaluated both immediately and 30 minutes (at 37° C after thawing. Supplementation with omegas increased sperm motility, vigor, and concentration; however, supplementation had no influence on semen freezability. In addition, there was no improvement in sperm motility after supplementation when the thawed cells were maintained at 37° C for 30 minutes. We concluded that dietary supplementation with omega-3 and -6 for 4 to 8 weeks can improve the quality of fresh semen, although it has no effect on the freezability of canine semen.

  18. Freezing behavior of adherent neuron-like cells and morphological change and viability of post-thaw cells.

    Science.gov (United States)

    Uemura, Makoto; Ishiguro, Hiroshi

    2015-04-01

    Freezing of nerve cells forming a neuronal network has largely been neglected, despite the fact that the cryopreservation of nerve cells benefits the study of cells in the areas of medicine and poison screening. Freezing of nerve cells is also attractive for studying cell morphology because of the characteristic long, thread-like neurites extending from the cell body. In the present study, freezing of neuron-like cells adhering to the substrate (differentiated PC12 cells), in physiological saline, was investigated in order to understand the fundamental freezing and thawing characteristics of nerve cells with neurites. The microscopic freezing behavior of cells under different cooling rates was observed. Next, the post-thaw morphological changes in the cells, including the cytoskeleton, were investigated and post-thaw cell viability was evaluated by dye exclusion using propidium iodide. Two categories of morphological changes, beading and shortening of the neurites, were found and quantified. Also, the morphological changes of neurites due to osmotic stress from sodium chloride were studied to gain a better understanding of causation. The results showed that morphological changes and cell death were promoted with a decrease in end temperature during freezing. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. Evaluating permafrost thaw vulnerabilities and hydrologic impacts in boreal Alaska (USA) watersheds by integrating field data and cryohydrogeologic modeling

    Science.gov (United States)

    Walvoord, Michelle; Voss, Clifford; Ebel, Brian; Minsley, Burke

    2017-04-01

    Permafrost environments undergo changes in hydraulic, thermal, chemical, and mechanical subsurface properties upon thaw. These property changes must be considered in addition to alterations in hydrologic, thermal, and topographic boundary conditions when evaluating shifts in the movement and storage of water in arctic and sub-arctic boreal regions. Advances have been made in the last several years with respect to multiscale geophysical characterization of the subsurface and coupled fluid and energy transport modeling of permafrost systems. Ongoing efforts are presented that integrate field data with cryohydrogeologic modeling to better understand and anticipate changes in subsurface water resources, fluxes, and flowpaths caused by climate warming and permafrost thawing. Analyses are based on field data from several sites in interior Alaska (USA) that span a broad north-south transition from continuous to discontinuous permafrost. These data include soil hydraulic and thermal properties and shallow permafrost distribution. The data guide coupled fluid and energy flow simulations that incorporate porewater liquid/ice phase change and the accompanying modifications in hydraulic and thermal subsurface properties. Simulations are designed to assess conditions conducive to active layer thickening and talik development, both of which are expected to affect groundwater storage and flow. Model results provide a framework for identifying factors that control the rates of permafrost thaw and associated hydrologic responses, which in turn influence the fate and transport of carbon.

  20. DOE Final Report on Collaborative Research. Quantifying Climate Feedbacks of the Terrestrial Biosphere under Thawing Permafrost Conditions in the Arctic

    Energy Technology Data Exchange (ETDEWEB)

    Zhuang, Qianlai [Purdue Univ., West Lafayette, IN (United States); Schlosser, C. Adam [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Melillo, Jerry M. [Marine Biological Lab. (MBL), Woods Hole, MA (United States); Anthony, Katey Walter [Univ. of Alaska, Fairbanks, AK (United States); Kicklighter, David [Marine Biological Lab. (MBL), Woods Hole, MA (United States); Gao, Xiang [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2015-11-03

    Our overall goal is to quantify the potential for threshold changes in natural emission rates of trace gases, particularly methane and carbon dioxide, from pan-arctic terrestrial systems under the spectrum of anthropogenically-forced climate warming, and the conditions under which these emissions provide a strong feedback mechanism to global climate warming. This goal is motivated under the premise that polar amplification of global climate warming will induce widespread thaw and degradation of the permafrost, and would thus cause substantial changes to the landscape of wetlands and lakes, especially thermokarst (thaw) lakes, across the Arctic. Through a suite of numerical experiments that encapsulate the fundamental processes governing methane emissions and carbon exchanges – as well as their coupling to the global climate system - we intend to test the following hypothesis in the proposed research: There exists a climate warming threshold beyond which permafrost degradation becomes widespread and stimulates large increases in methane emissions (via thermokarst lakes and poorly-drained wetland areas upon thawing permafrost along with microbial metabolic responses to higher temperatures) and increases in carbon dioxide emissions from well-drained areas. Besides changes in biogeochemistry, this threshold will also influence global energy dynamics through effects on surface albedo, evapotranspiration and water vapor. These changes would outweigh any increased uptake of carbon (e.g. from peatlands and higher plant photosynthesis) and would result in a strong, positive feedback to global climate warming.

  1. Stem water transport and freeze-thaw xylem embolism in conifers and angiosperms in a Tasmanian treeline heath.

    Science.gov (United States)

    Feild, Taylor S; Brodribb, Tim

    2001-05-01

    The effect of freezing on stem xylem hydraulic conductivity and leaf chlorophyll a fluorescence was measured in 12 tree and shrub species from a treeline heath in Tasmania, Australia. Reduction in stem hydraulic conductivity after a single freeze-thaw cycle was minimal in conifers and the vessel-less angiosperm species Tasmannia lanceolata (Winteraceae), whereas mean loss of conductivity in vessel-forming angiosperms fell in the range 17-83%. A positive linear relationship was observed between percentage loss of hydraulic conductivity by freeze-thaw and the average conduit diameter across all 12 species. This supports the hypothesis that large-diameter vascular conduits have a greater likelihood of freeze-thaw cavitation because larger bubbles are produced, which are more likely to expand under tension. Leaf frost tolerances, as measured by a 50% loss of maximum PSII quantum yield, varied from -6 to -13°C, indicating that these species were more frost-sensitive than plants from northern hemisphere temperate forest and treeline communities. There was no evidence of a relationship between frost tolerance of leaves and the resilience of stem water transport to freezing, suggesting that low temperature survival and the resistance of stem water transport to freezing are independently evolving traits. The results of this study bear on the ecological importance of stem freezing in the southern hemisphere treeline zones.

  2. A combination of solvent extraction and freeze thaw for oil recovery from petroleum refinery wastewater treatment pond sludge.

    Science.gov (United States)

    Hu, Guangji; Li, Jianbing; Hou, Haobo

    2015-01-01

    A combination of solvent extraction and freeze thaw was examined for recovering oil from the high-moisture petroleum refinery wastewater treatment pond sludge. Five solvents including cyclohexane (CHX), dichloromethane (DCM), methyl ethyl ketone (MEK), ethyl acetate (EA), and 2-propanol (2-Pro) were examined. It was found that these solvents except 2-Pro showed a promising oil recovery rate of about 40%, but the recycling of DCM solvent after oil extraction was quite low. Three solvents (CHX, MEK and EA) were then selected for examining the effect of freeze/thaw treatment on improving the quality of recovered oil. This treatment increased the total petroleum hydrocarbon (TPH) content in recovered oil from about 40% to 60% for both MEK and EA extractions, but little effect was observed for CHX extraction. Although the solid residue after oil recovery had a significantly decreased TPH content, a high concentration of heavy metals was observed, indicating that this residue may require proper management. In general, the combination of solvent extraction with freeze/thaw is effective for high-moisture oily hazardous waste treatment. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. In vitro fertilization using frozen-thawed feline epididymal spermatozoa from corpus and cauda regions.

    Science.gov (United States)

    Kunkitti, Panisara; Axnér, Eva; Bergqvist, Ann-Sofi; Sjunnesson, Ylva

    2016-10-01

    Epididymal sperm preservation offers a potential for rescuing genetic material from endangered or valuable animals after injury or death. Spermatozoa from corpus, as well as from cauda, have the capability to be motile and to undergo capacitation and can thus potentially be preserved for assisted reproductive technologies. In the present study, feline frozen-thawed epididymal spermatozoa from corpus and cauda regions were investigated for their ability to fertilize homologous oocytes and further embryo development in vitro. Epididymal spermatozoa from corpus and cauda of seven cats were cryopreserved and used for IVF. Cumulus-oocyte complexes (n = 419) were obtained from female cats after routine spaying. Frozen-thawed corpus epididymal spermatozoa showed similar properties of acrosome integrity, membrane integrity, and chromatin integrity as frozen-thawed spermatozoa from cauda except corpus spermatozoa showed lower motility (P epididymal spermatozoa was confirmed by similar number of embryos developing to the two- and four-cell stages compared with sperm from cauda (32.03% vs. 33.33%). However, oocytes fertilized with corpus spermatozoa had lower potential to develop to the blastocyst stage (6.79%) and had lower cell numbers compared to oocytes fertilized with cauda spermatozoa (14.08%). In conclusion, spermatozoa from corpus epididymis had a similar capability to fertilize homologous oocytes in vitro as sperm from cauda but resulted in fewer embryos developing to the blastocyst stage compared to spermatozoa from the cauda. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Intravaginal artificial insemination in bitches using frozen/thawed semen after dilution in powdered coconut water (ACP-106c).

    Science.gov (United States)

    Uchoa, D C; Silva, T F P; Mota Filho, A C; Silva, L D M

    2012-12-01

    The aim of this study was to evaluate powdered coconut water extender (ACP-106c; ACP Serviços Tecnológicos Ltda, ACP Biotecnologia, Fortaleza, Ceará, Brazil) as a diluent for freezing dog semen and the fertility after vaginal insemination of semen frozen therein. Ten ejaculates were collected from five dogs, evaluated fresh, diluted in ACP-106c, 10% egg yolk and 6% glycerol, cooled and frozen. In the first phase of the study, straws with frozen semen were thawed and immediately subjected to the same analysis as the fresh semen and, in addition, to Computer-Assisted Semen Analysis (CASA). In phase 2, 10 bitches that had been subjected to natural breeding during a preceding oestrous cycle were vaginally inseminated with thawed semen that had been re-diluted in ACP-106c. After thawing, a mean of 77% sperm motility was obtained through subjective analysis and 77.3% through CASA. Following artificial insemination, a 60% pregnancy rate was observed, resulting in a 50% parturition rate and a mean litter size of 3.4 (SEM 0.6), with 47.1% males and 52.9% females. ACP-106c can be successfully used for freezing canine semen, and vaginal deposition of such semen yields similar pregnancy rates to those reported in other studies. © 2012 Blackwell Verlag GmbH.

  5. Numerical Modeling of the Effect of Thawing of Soil in the Area of Placing Tanks for Storage Fuel of Thermal Power Plants and Boiler

    Directory of Open Access Journals (Sweden)

    Polovnikov V.Yu.

    2016-01-01

    Full Text Available This paper describes the numerical modeling of heat transfer in the area placing of the tank for storage fuel of thermal power plant and boiler with considering the influence of thawing of the soil. We have established that the thawing of the soil in the area of placing of the tank for storage fuel of thermal power plant and boiler have little effect on the change of heat loss.

  6. Freeze-Thaw Performance and Moisture-Induced Damage Resistance of Base Course Stabilized with Slow Setting Bitumen Emulsion-Portland Cement Additives

    OpenAIRE

    Mojtaba Shojaei Baghini; Amiruddin Ismail

    2015-01-01

    Freeze-thaw (FT) cycles and moisture susceptibility are important factors influencing the geotechnical characteristics of soil-aggregates. Given the lack of published information on the behavior of cement-bitumen emulsion-treated base (CBETB) under environmental conditions, especially freezing and thawing, this study investigated the effects of these additives on the CBETB performance. The primary goal was to evaluate the resistance of CBETB to moisture damage by performing FT, Marshall condi...

  7. Frozen-thawed rhesus sperm retain normal morphology and highly progressive motility but exhibit sharply reduced efficiency in penetrating cervical mucus and hyualuronic acid gel

    OpenAIRE

    Tollner, Theodore L; Dong, Qiaoxiang; VandeVoort, Catherine A

    2010-01-01

    The preservation of the genetic diversity of captive populations of rhesus monkeys is critical to the future of biomedical research. Cryopreservation of rhesus macaque sperm is relatively simple to perform, yields high post-thaw motility, and theoretically, provides via artificial insemination (AI) a way to easily transfer genetics among colonies of animals. In the interest of optimizing semen cryopreservation methods for use with vaginal AI, we evaluated the ability of frozen-thawed rhesus s...

  8. Evaluation of the function of fresh and frozen-thawed sex-sorted and non-sorted stallion spermatozoa using a heterologous oocyte binding assay.

    Science.gov (United States)

    Clulow, J R; Evans, G; Maxwell, W M C; Morris, L H A

    2010-01-01

    The aim of the present study was to evaluate the potential oocyte binding ability and functional integrity of fresh or frozen-thawed, sex-sorted or non-sorted stallion spermatozoa. In the absence of effective IVF procedures in the horse, a heterologous sperm-binding assay was used as an indicator of fertilising capacity to assess differences in the ability of stallion spermatozoa to bind to bovine oocytes. The functional integrity of four treatment groups was assessed: (1) fresh non-sorted spermatozoa; (2) fresh sex-sorted spermatozoa; (3) frozen-thawed non-sorted spermatozoa; and (4) frozen-thawed sex-sorted spermatozoa. Spermatozoa found in association with the zona pellucida of the bovine oocytes were deemed 'attached' or 'bound' depending on their characterisation as either acrosome intact or acrosome reacted, respectively. Significantly less frozen-thawed spermatozoa were found attached to the oocytes compared with fresh spermatozoa. No significant differences were identified between the number of attached sex-sorted and non-sorted frozen-thawed spermatozoa. However, significantly more sex-sorted than non-sorted fresh spermatozoa were found attached to the oocytes after 1 h coincubation, although after 3 h coincubation this difference was no longer apparent. In conclusion, sex-sorted fresh and frozen-thawed stallion spermatozoa are functionally capable of attaching and binding to bovine oocytes in vitro. Furthermore, fresh sex-sorted spermatozoa attach better than non-sorted spermatozoa, suggesting that they have a more advanced capacitation-like status.

  9. Effects of diluents and plasma on honey bee (Apis mellifera L.) drone frozen-thawed semen fertility.

    Science.gov (United States)

    Gül, Aziz; Şahinler, Nuray; Onal, Ali G; Hopkins, Brandon K; Sheppard, Walter S

    2017-10-01

    Cryopreservation is an advanced method used to protect germplasm in liquid nitrogen. Honey bees are of special interest to protect because of their pollination activity and critical role in agriculture. There has been important progress in the cryopreservation of honey bee germplasm in recent years, leading to practical recovery of genetic material for breeding purposes following freezing. However, there remains room for improvement and the goal of the present study was to evaluate the effect of different "extenders" added post-thaw on the fertilization rate of cryopreserved honey bee semen. The purpose of adding extender post-thaw was to dilute the cryoprotectant to remove chemicals after centrifugation because of potential adverse effects. The control consisted of frozen-thawed semen without the addition of an extender; treatment groups included the addition of one of the following extenders: glucose solution, fresh ram semen plasma, fresh honey bee semen plasma, extender solution. All of the above treatments and frozen-thawed control were compared to fresh semen. For each group, 15 virgin queens were instrumentally inseminated with the semen-diluent solution and introduced into nucleus colonies to determine the brood patterns of the queens. Percentages of worker brood produced in the fresh semen, frozen-thawed semen control, glucose, fresh ram semen plasma, fresh honey bee semen plasma, and extender solution supplemented groups were 98.±1.1%, 47.0 ± 0.9%, 3.0 ± 0.8%, 0.3 ± 0.1%, 48.1 ± 4.1% and 40.3 ± 2.4%, respectively. Similiarly, spermatozoa numbers in the spermathecae of the same treatment groups were 3.6 × 10 6 , 1.6 × 10 6 , 7.3 × 10 5 , 4.7 × 10 5 , 8.1 × 10 5 , and 4.6 × 10 5 spermatozoa for the same treatment, respectively. The differences in both worker brood percentage and sperm count in the spermatheca were statistically significant (P drone semen plasma group. We found a positive correlation between sperm count in

  10. Fuel-reduction management alters plant composition, carbon and nitrogen pools, and soil thaw in Alaskan boreal forest

    Science.gov (United States)

    Melvin, April M.; Celis, Gerardo; Johnstone, Jill F.; McGuire, A. David; Genet, Helene; Schuur, Edward A.G.; Rupp, T. Scott; Mack, Michelle C.

    2018-01-01

    Increasing wildfire activity in Alaska's boreal forests has led to greater fuel-reduction management. Management has been implemented to reduce wildfire spread, but the ecological impacts of these practices are poorly known. We quantified the effects of hand-thinning and shearblading on above- and belowground stand characteristics, plant species composition, carbon (C) and nitrogen (N) pools, and soil thaw across 19 black spruce (Picea mariana) dominated sites in interior Alaska treated 2-12 years prior to sampling. The density of deciduous tree seedlings was significantly higher in shearbladed areas compared to unmanaged forest (6.4 vs. 0.1 stems m−2), and unmanaged stands exhibited the highest mean density of conifer seedlings and layers (1.4 stems m−2). Understory plant community composition was most similar between unmanaged and thinned stands. Shearblading resulted in a near complete loss of aboveground tree biomass C pools while thinning approximately halved the C pool size (1.2 kg C m−2 compared to 3.1 kg C m−2 in unmanaged forest). Significantly smaller soil organic layer (SOL) C and N pools were observed in shearbladed stands (3.2 kg C m−2 and 116.8 g N m−2) relative to thinned (6.0 kg C m−2 and 192.2 g N m−2) and unmanaged (5.9 kg C m−2 and 178.7 g N m−2) stands. No difference in C and N pool sizes in the uppermost 10 cm of mineral soil was observed among stand types. Total C stocks for measured pools was 2.6 kg C m−2 smaller in thinned stands and 5.8 kg C m−2smaller in shearbladed stands when compared to unmanaged forest. Soil thaw depth averaged 13 cm deeper in thinned areas and 46 cm deeper in shearbladed areas relative to adjacent unmanaged stands, although variability was high across sites. Deeper soil thaw was linked to shallower SOL depth for unmanaged stands and both management types, however for any given SOL depth, thaw tended to be deeper in shearbladed areas compared to unmanaged forest. These findings indicate

  11. Fuel-reduction management alters plant composition, carbon and nitrogen pools, and soil thaw in Alaskan boreal forest.

    Science.gov (United States)

    Melvin, April M; Celis, Gerardo; Johnstone, Jill F; McGuire, A David; Genet, Helene; Schuur, Edward A G; Rupp, T Scott; Mack, Michelle C

    2018-01-01

    Increasing wildfire activity in Alaska's boreal forests has led to greater fuel-reduction management. Management has been implemented to reduce wildfire spread, but the ecological impacts of these practices are poorly known. We quantified the effects of hand-thinning and shearblading on above- and belowground stand characteristics, plant species composition, carbon (C) and nitrogen (N) pools, and soil thaw across 19 sites dominated by black spruce (Picea mariana) in interior Alaska treated 2-12 years prior to sampling. The density of deciduous tree seedlings was significantly higher in shearbladed areas compared to unmanaged forest (6.4 vs. 0.1 stems/m2 ), and unmanaged stands exhibited the highest mean density of conifer seedlings and layers (1.4 stems/m2 ). Understory plant community composition was most similar between unmanaged and thinned stands. Shearblading resulted in a near complete loss of aboveground tree biomass C pools while thinning approximately halved the C pool size (1.2 kg C/m2 compared to 3.1 kg C/m2 in unmanaged forest). Significantly smaller soil organic layer (SOL) C and N pools were observed in shearbladed stands (3.2 kg C/m2 and 116.8 g N/m2 ) relative to thinned (6.0 kg C/m2 and 192.2 g N/m2 ) and unmanaged (5.9 kg C/m2 and 178.7 g N/m2 ) stands. No difference in C and N pool sizes in the uppermost 10 cm of mineral soil was observed among stand types. Total C stocks for measured pools was 2.6 kg C/m2 smaller in thinned stands and 5.8 kg C/m2 smaller in shearbladed stands when compared to unmanaged forest. Soil thaw depth averaged 13 cm deeper in thinned areas and 46 cm deeper in shearbladed areas relative to adjacent unmanaged stands, although variability was high across sites. Deeper soil thaw was linked to shallower SOL depth for unmanaged stands and both management types, however for any given SOL depth, thaw tended to be deeper in shearbladed areas compared to unmanaged forest. These findings indicate that fuel

  12. Investigation of Seasonal Landscape Freeze/Thaw Cycles in Relation to Cloud Structure in the High Northern Latitudes

    Science.gov (United States)

    Smith, Cosmo

    2011-01-01

    The seasonal freezing and thawing of Earth's cryosphere (the portion of Earth's surface permanently or seasonally frozen) has an immense impact on Earth's climate as well as on its water, carbon and energy cycles. During the spring, snowmelt and the transition between frozen and non-frozen states lowers Earth's surface albedo. This change in albedo causes more solar radiation to be absorbed by the land surface, raising surface soil and air temperatures as much as 5 C within a few days. The transition of ice into liquid water not only raises the surface humidity, but also greatly affects the energy exchange between the land surface and the atmosphere as the phase change creates a latent energy dominated system. There is strong evidence to suggest that the thawing of the cryosphere during spring and refreezing during autumn is correlated to local atmospheric conditions such as cloud structure and frequency. Understanding the influence of land surface freeze/thaw cycles on atmospheric structure can help improve our understanding of links between seasonal land surface state and weather and climate, providing insight into associated changes in Earth's water, carbon, and energy cycles that are driven by climate change.Information on both the freeze/thaw states of Earth's land surface and cloud characteristics is derived from data sets collected by NOAA's Special Sensor Microwave/Imager (SSM/I), the Advanced Microwave Scanning Radiometer on NASA's Earth Observing System(AMSR-E), NASA's CloudSat, and NASA's SeaWinds-on-QuickSCAT Earth remote sensing satellite instruments. These instruments take advantage of the microwave spectrum to collect an ensemble of atmospheric and land surface data. Our analysis uses data from radars (active instruments which transmit a microwave signal toward Earth and measure the resultant backscatter) and radiometers (passive devices which measure Earth's natural microwave emission) to accurately characterize salient details on Earth's surface

  13. Small-scale lobes on Mars: Solifluction, thaw and clues to gully formation.

    Science.gov (United States)

    Johnsson, Andreas; Reiss, Dennis; Conway, Susan; Hauber, Ernst; Hiesinger, Harald

    2017-04-01

    Small-scale lobes (SSL) on Mars are landforms that show striking morphologic resemblance to solifluction lobes on Earth [1,2]. Solifluction is the net downslope movement of soil driven by phase changes of near-surface water due to freeze-thaw activity [3]. SSLs on Mars consist of an arcuate front (riser) tens to hundreds of meters wide [1,2]. Risers are typically decimeters to a few meters (water in the shallow subsurface in the recent past. This study aims to determine the distribution of SSL in the southern hemisphere and to investigate their relationship to gullies and other possible periglacial landforms such as patterned ground and polygonal terrain. Collectively, these landforms may be linked to phase changes of water at the surface or in the shallow subsurface. We show that the distribution of SLLs in the southern hemisphere roughly mirrors that in the northern hemisphere distribution. Hence, SLLs are hemispherically bimodal-distributed landforms, similar to polygonal terrain [e.g. 5] and gullies [e.g. 8]. However, despite more abundant sloping terrain in the southern hemisphere, fewer SLLs are observed, except in the Charitum Montes region. This is in contrast to gully landforms which are more abundant in the southern hemisphere. Martian gully landforms and their formative processes have received considerable attention in the last decade and there are currently conflicting ideas whether liquid water [e.g. 9] or CO2-triggered mass wasting [e.g. 10] are the primary agents of erosion. As there are no CO2 frost triggered hypotheses that can explain the occurrence of SSL, a thaw-based hypothesis could explain both landforms. In the latter scenario gullies and SLLs may form a hydrologic continuum where available water content governs the type of landform produced. Solifluction would require ice lens formation (excess ice) to develop. Excess ice was encountered by the Phoenix lander in 2008 [11]. Furthermore, modelling attempts may suggest that ice lenses could be

  14. Soy lecithin interferes with mitochondrial function in frozen-thawed ram spermatozoa.

    Science.gov (United States)

    Del Valle, I; Gómez-Durán, A; Holt, W V; Muiño-Blanco, T; Cebrián-Pérez, J A

    2012-01-01

    Egg yolk and milk are the 2 major membrane cryoprotectants commonly used in freezing media for the long-term preservation of semen (alone or in combination with others). However, in recent years, there have been increasing arguments against the use of egg yolk or milk because of the risk of introducing diseases through the use of cryopreserved semen. In this study, we analyzed the protective effect of lecithin as an alternative to egg yolk for the cryopreservation of ram semen, using a range of functional markers for sperm viability, motility, apoptosis, and mitochondrial functionality analyses (mitochondrial inner membrane surface [MIMS], mitochondrial inner membrane potential [MIMP], and cell membrane potential) as methods of assessment in samples diluted in 3 different media: Tris-citrate-glucose as control and 2 media supplemented with soy lecithin or egg yolk. The results showed that lecithin was able to effectively protect certain sperm quality characteristics against freezing-induced damage. However, lecithin induced loss of mitochondrial membrane potential or mitochondrial loss that was not reflected by modifications in sperm motility in fresh semen. MIMS and MIMP values decreased in thawed lecithin-treated samples, concomitant with a lower (P lecithin may have affected the inner mitochondrial membrane in frozenthawed spermatozoa and confirmed that sublethal damages that seriously affect sperm functionality, not detected by classic sperm quality analyses, can be evidenced by changes in the inner mitochondrial membrane surface. These findings strengthen the relationship between mitochondrial membrane potential and motility and show that the mitochondrial alterations induced by the cryopreservation process could be specific targets for the improvement of semen cryopreservation protocols.

  15. Early life history transitions and recruitment of Picea mariana in thawed boreal permafrost peatlands.

    Science.gov (United States)

    Camill, Philip; Chihara, Laura; Adams, Brad; Andreassi, Christian; Barry, Ann; Kalim, Sahir; Limmer, Jacob; Mandell, Mike; Rafert, Greg

    2010-02-01

    Black spruce (Picea mariana) is the most abundant tree species in the boreal biome, but little is known about how climate warming may change recruitment in peatlands, especially those affected by permafrost thaw. We used results from a seven-year study in northern Manitoba, Canada, to address the following questions: (1) What is the relative importance of early life history transitions on P. mariana recruitment? (2) How are these transitions mediated by biological and environmental factors, including competition, facilitation, disease, herbivory, water table depth, and soil nutrients? (3) Do interactions among these factors create additional recruitment limitations beyond those imposed by environmental factors changing with climate warming, such as hydrology? Seed rain was measured over six years on forested permafrost plateaus and in neighboring collapse scar bogs. Seed germination and seedling survival and growth were measured over 4-5 years in collapse scars and assessed across a three-level water table treatment. Survival and growth experiments examined additional combinations of above- and belowground vascular plant competition and fertilizer addition. Results showed that failure of germination and survival on growing moss surfaces and reduced survival of seedlings in wetter microsites were primary constraints. Seed influx was significantly lower in collapse scars but likely did not limit recruitment. Biological and environmental factors mediating these life history transitions also differed in relative importance, and interactions among them tended to amplify recruitment limitation. Seedling survival was most strongly controlled by fast-growing mosses in wet microsites but also was influenced by apparent drowning in wet plots, herbivory, and loss of foliage caused by a fungal pathogen. Seedling growth was strongly controlled by water table depth, nutrient and competition levels, and fungal pathogens. Multiple, interacting factors will affect P. mariana

  16. Fracturing and Damage to Sandstone Under Coupling Effects of Chemical Corrosion and Freeze-Thaw Cycles

    Science.gov (United States)

    Han, Tielin; Shi, Junping; Cao, Xiaoshan

    2016-11-01

    Rapid freeze-thaw (FT) cycles were adopted to explore the damage deterioration mechanism and mechanical properties of sandstone specimens under the coupling effects of different chemical solutions and FT cycles. The variation regularities of the FT cycles and physical and mechanical properties of sandstone specimens immersed in different chemical solutions were analyzed by using sandstone sampled from a Chinese riverbank slope. The damage variable based on porosity variation was used in the quantitative analysis of the damage to the sandstone under the coupling effects of chemical corrosion and FT cycles. Experimental results showed that the sandstone specimens weakened substantially under those effects. Their fracture toughness K IC, splitting tensile strength, and compressive strength showed a similar deteriorating trend with various numbers of FT cycles. However, a difference exists in the deterioration degree of their mechanical parameters, i.e., the deterioration degree of their fracture toughness K IC is the greatest followed by that of splitting tensile strength, and that of compressive strength is relatively small. Strong acid solutions may aggravate the deterioration of FT damage in sandstones, but at the early stage of the experiment, strong alkaline solutions inhibited sandstone damage deterioration. However, the inhibiting effect disappeared when the number of FT cycles exceeded 25. The different chemical solutions had a different effect on the FT damage degree of the sandstone specimens; for example, SO4 2- ions had a greater effect on FT damage than did HCO3 - ions. Water-chemical solutions and FT cycles promote each other in deteriorating rocks and simultaneously affect the damage deterioration degree of sandstones.

  17. Effect of freeze-thaw cycling on grain size of biochar.

    Science.gov (United States)

    Liu, Zuolin; Dugan, Brandon; Masiello, Caroline A; Wahab, Leila M; Gonnermann, Helge M; Nittrouer, Jeffrey A

    2018-01-01

    Biochar may improve soil hydrology by altering soil porosity, density, hydraulic conductivity, and water-holding capacity. These properties are associated with the grain size distributions of both soil and biochar, and therefore may change as biochar weathers. Here we report how freeze-thaw (F-T) cycling impacts the grain size of pine, mesquite, miscanthus, and sewage waste biochars under two drainage conditions: undrained (all biochars) and a gravity-drained experiment (mesquite biochar only). In the undrained experiment plant biochars showed a decrease in median grain size and a change in grain-size distribution consistent with the flaking off of thin layers from the biochar surface. Biochar grain size distribution changed from unimodal to bimodal, with lower peaks and wider distributions. For plant biochars the median grain size decreased by up to 45.8% and the grain aspect ratio increased by up to 22.4% after 20 F-T cycles. F-T cycling did not change the grain size or aspect ratio of sewage waste biochar. We also observed changes in the skeletal density of biochars (maximum increase of 1.3%), envelope density (maximum decrease of 12.2%), and intraporosity (porosity inside particles, maximum increase of 3.2%). In the drained experiment, mesquite biochar exhibited a decrease of median grain size (up to 4.2%) and no change of aspect ratio after 10 F-T cycles. We also document a positive relationship between grain size decrease and initial water content, suggesting that, biochar properties that increase water content, like high intraporosity and pore connectivity large intrapores, and hydrophilicity, combined with undrained conditions and frequent F-T cycles may increase biochar breakdown. The observed changes in biochar particle size and shape can be expected to alter hydrologic properties, and thus may impact both plant growth and the hydrologic cycle.

  18. Seminal plasma proteins interacting with sperm surface revert capacitation indicators in frozen-thawed ram sperm.

    Science.gov (United States)

    Ledesma, Alba; Fernández-Alegre, Estela; Cano, Adriana; Hozbor, Federico; Martínez-Pastor, Felipe; Cesari, Andreína

    2016-10-01

    This study was conducted to evaluate the effects of interacting seminal plasma proteins (iSPP) obtained by AV or EE on frozen-thawed ram sperm in order to test the hypothesis whether this fraction could be sufficient to emulate the effect of complete seminal plasma (SP). Additionally, we evaluated whether these proteins have a differential effect between spermatozoa from high and low fertility rams and between breeding and non-breeding seasons. We assessed sperm motility, quality parameters (intracellular reactive oxygen species, membrane fluidity, plasma membrane permeability and mitochondrial activity) and capacitation status. The main findings from this work were: i) iSPP had no effect on sperm motility, whereas SP (AV or EE) addition produced the highest values of total motility (74.13±2.99 and 72.27±2.99 for AV and EE, respectively) and progressive motility (64.97±2.64 and 63.73±2.64 for AV and EE, respectively); ii) iSPP had no effect on sperm quality parameters (p>0.05), but whole SP improved all parameters evaluated. Moreover, SP collected by AV yielded significantly higher viability (44.60±2.87) and sperm with stable plasma membrane (44.56±2.49) comparing with the addition of SP collected by EE (35.80±2.47 and 36.67±1.71, respectively); iii) iSPP and SP collected by EE, but not by AV, reverted molecular signals of capacitation as protein tyrosine phosphorylation caused by freezing temperatures; iv) there were no effects of fertility or season in sperm quality parameters evaluated. This study demonstrated that, although the iSPP have a clear decapacitating effect, including the ability to revert cryo-capacitation indicators, they are not sufficient to emulate the effects of complete SP regarding sperm functional parameters. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Continuous removal of glycerol from frozen-thawed red blood cells in a microfluidic membrane device.

    Science.gov (United States)

    Lusianti, Ratih E; Higgins, Adam Z

    2014-09-01

    Cryopreservation of human red blood cells (RBCs) in the presence of 40% glycerol allows a shelf-life of 10 years, as opposed to only 6 weeks for refrigerated RBCs. Nonetheless, cryopreserved blood is rarely used in clinical therapy, in part because of the requirement for a time-consuming (∼1 h) post-thaw wash process to remove glycerol before the product can be used for transfusion. The current deglycerolization process involves a series of saline washes in an automated centrifuge, which gradually removes glycerol from the cells in order to prevent osmotic damage. We recently demonstrated that glycerol can be extracted in as little as 3 min without excessive osmotic damage if the composition of the extracellular solution is precisely controlled. Here, we explore the potential for carrying out rapid glycerol extraction using a membrane-based microfluidic device, with the ultimate goal of enabling inline washing of cryopreserved blood. To assist in experimental design and device optimization, we developed a mass transfer model that allows prediction of glycerol removal, as well as the resulting cell volume changes. Experimental measurements of solution composition and hemolysis at the device outlet are in reasonable agreement with model predictions, and our results demonstrate that it is possible to reduce the glycerol concentration by more than 50% in a single device without excessive hemolysis. Based on these promising results, we present a design for a multistage process that is predicted to safely remove glycerol from cryopreserved blood in less than 3 min.

  20. Viabilitas Spermatozoa Babi dalam Pengencer BTS (Beltsville Thawing Solution yang Dimodifikasi pada Penyimpanan Berbeda

    Directory of Open Access Journals (Sweden)

    N. L. G. Sumardani

    2008-08-01

    Full Text Available The optimal storage temperature for preserve boar semen is 17-18°C. The temperature fluctuations can decrease sperm viability. The aim of this study was to obtain a boar semen extender for Artificial Insemination (AI at a certain distance area. The observation was based on the sperm viability in modified Beltsville Thawing Solution (BTS extender in different storage, and the effect of storage system i.e.: room temperature (22°C and styrofoam box (18°C were conducted for this purpose. The research used a completely randomized design (CRD with two factorial i.e.: BTS and M-BTS extender (F1, room temperature and styrofoam box (F2. Semen from three years old Yorkshire boars (n = 3 were collected twice a week by glove hand method. Semen characteristics and their quality were evaluated macro and microscopically. These semen were added with BTS and M-BTS extender up to fourfold volume (ratio 1 : 3. This is based on the assumption of AI dose of 2 - 3 x 109cells/80ml and the sperm motility and viability were evaluated every six hours for 24 hours observation. The results showed that fresh semen characteristics were good, with the percentage of sperm motility 65.56±2.55% and sperm viability of 87.70±2.87%. The best extender found in this experiment of 24 hours observation was BTS extender with sperm motility 53.33±3.33% in styrofoam box. In conclusion, BTS extender can maintain the quality of spermatozoa stored in styrofoam box for about 24 hours with sperm motility 40%-50%, and the styrofoam box can be used as an alternative container for insemination program in the field.

  1. Assimilation of Freeze - Thaw Observations into the NASA Catchment Land Surface Model

    Science.gov (United States)

    Farhadi, Leila; Reichle, Rolf H.; DeLannoy, Gabrielle J. M.; Kimball, John S.

    2014-01-01

    The land surface freeze-thaw (F-T) state plays a key role in the hydrological and carbon cycles and thus affects water and energy exchanges and vegetation productivity at the land surface. In this study, we developed an F-T assimilation algorithm for the NASA Goddard Earth Observing System, version 5 (GEOS-5) modeling and assimilation framework. The algorithm includes a newly developed observation operator that diagnoses the landscape F-T state in the GEOS-5 Catchment land surface model. The F-T analysis is a rule-based approach that adjusts Catchment model state variables in response to binary F-T observations, while also considering forecast and observation errors. A regional observing system simulation experiment was conducted using synthetically generated F-T observations. The assimilation of perfect (error-free) F-T observations reduced the root-mean-square errors (RMSE) of surface temperature and soil temperature by 0.206 C and 0.061 C, respectively, when compared to model estimates (equivalent to a relative RMSE reduction of 6.7 percent and 3.1 percent, respectively). For a maximum classification error (CEmax) of 10 percent in the synthetic F-T observations, the F-T assimilation reduced the RMSE of surface temperature and soil temperature by 0.178 C and 0.036 C, respectively. For CEmax=20 percent, the F-T assimilation still reduces the RMSE of model surface temperature estimates by 0.149 C but yields no improvement over the model soil temperature estimates. The F-T assimilation scheme is being developed to exploit planned operational F-T products from the NASA Soil Moisture Active Passive (SMAP) mission.

  2. Influence of glutathione on kinetic parameters of frozen-thawed spermatozoa from Ovchepolian Pramenka rams

    Directory of Open Access Journals (Sweden)

    Martin Nikolovski

    2014-10-01

    Full Text Available Motility patterns of spermatozoa are an indicator of their fertilizing capacity. Reduced glutathione (GSH has been reported to induce positive effects on biological quality of the frozen-thawed spermatozoa. The aim of this study was to investigate the effects of GSH addition to semen extender on the following kinetic parameters: continuous line velocity (VSL, average path velocity (VAP, curvilinear velocity (VCL, amplitude of lateral head displacement (ALH, linearity (LIN, straightness (STR, beat cross frequency (BCF, total motility (tMOT and progressive motility (pMOT, and to appoint them as indicators of its presence. A soybean-based extender was used for dilution of the semen samples, fractioned in two parts, one containing GSH (5 mMol/ml and second without GSH. The ejaculates (n=48 were collected from two rams (January – May, 2013 which were classified in two groups according to the used extender: Group 1 (with GSH, n=24 and Group 2 (without GSH, n=24, and then frozen in liquid nitrogen on -196°C degrees in a programmable freezer. Assessment of the samples has been performed postthawing (30 sec. at 37°C on CASA equipment, acquiring kinetic parameters. Results showed that only VSL and BCF have a statistically significant difference between group1 and group 2 (102.98±15.13 vs. 88.47±20.63, t=2.77, p<0.01 and 32.01±2.68 vs. 89.47±2.92, t=3.13, p<0.01, respectively. The summary of the investigation concludes that none of the kinetic parameters could be appointed as indicators that confer the positive effect of GSH as an additive to soy-bean semen extender.

  3. Frozen-thawed rhesus sperm retain normal morphology and highly progressive motility but exhibit sharply reduced efficiency in penetrating cervical mucus and hyaluronic acid gel.

    Science.gov (United States)

    Tollner, Theodore L; Dong, Qiaoxiang; VandeVoort, Catherine A

    2011-02-01

    The preservation of the genetic diversity of captive populations of rhesus monkeys is critical to the future of biomedical research. Cryopreservation of rhesus macaque sperm is relatively simple to perform, yields high post-thaw motility, and theoretically, provides via artificial insemination (AI) a way to easily transfer genetics among colonies of animals. In the interest of optimizing semen cryopreservation methods for use with vaginal AI, we evaluated the ability of frozen-thawed rhesus sperm to penetrate periovulatory cervical mucus (CM). Motile sperm concentration of pre-freeze ("fresh") and post-thawed ("thawed") samples from five different males were normalized for both computer assisted sperm motion analysis and CM penetration experiments. Sperm samples were deposited into slide chambers containing CM or gel composed of hyaluronic acid (HA) as a surrogate for CM and numbers of sperm were recorded as they entered a video field a preset distance from the sperm suspension-CM (or HA) interface. Fresh and thawed sperm were dried on glass slides, "Pap"-stained, and assessed for changes in head dimensions and head and flagellar shape. While retaining better than 80% of fresh sperm progressive motility, thawed sperm from the same ejaculate retained on average only 18.6% of the CM penetration ability. Experiments using HA gel yielded similar results only with reduced experimental error and thus improved detection of treatment differences. Neither the percentage of abnormal forms nor head dimensions differed between fresh and thawed sperm. While findings suggests that sperm-CM interaction is a prominent factor in previous failures of vaginal AI with cryopreserved macaque sperm, neither sperm motility nor morphology appears to account for changes in the ability of cryopreserved sperm to penetrate CM. Our data points to a previously unidentified manifestation of cryodamage which may have implications for assessment of sperm function beyond the cervix and across

  4. Brown bear sperm double freezing: Effect of elapsed time and use of PureSperm(®) gradient between freeze-thaw cycles.

    Science.gov (United States)

    Alvarez-Rodríguez, Manuel; Alvarez, Mercedes; López-Urueña, Elena; Martínez-Rodriguez, Carmen; Borragan, Santiago; Anel-López, Luis; de Paz, Paulino; Anel, Luis

    2013-12-01

    The use of sexed spermatozoa has great potential to captive population management in endangered wildlife. The problem is that the sex-sorting facility is a long distance from the semen collection place and to overcome this difficulty two freeze-thaw cycles may be necessary. In this study, effects of refreezing on brown bear electroejaculated spermatozoa were analyzed. We carried out two experiments: (1) to assess the effects of the two freezing-thawing cycles on sperm quality and to analyze three different elapsed times between freezing-thawing cycles (30, 90 and 180 min), and (2) to analyze the use of PureSperm between freezing-thawing cycles to select a more motile and viable sperm subpopulation which better survived first freezing. The motility, viability and undamaged acrosomes were significantly reduced after the second thawing respect to first thawing into each elapsed time group, but the elapsed times did not significantly affect the viability and acrosome status although motility was damaged. Our results with the PureSperm gradient showed higher values of viability in freezability of select sample (pellet) respect to the rest of the groups and it also showed a significant decrease in the number of acrosome damaged. In summary, the double freezing of bear semen selected by gradient centrifugation is qualitatively efficient, and thus could be useful to carry out a sex-sorting of frozen-thawed bear spermatozoa before to send the cryopreserved sample to a biobank. Given the low recovery of spermatozoa after applying a selection gradient, further studies will be needed to increase the recovery rate without damaging of the cell quality. Copyright © 2013 Elsevier Inc. All rights reserved.

  5. Treating boar sperm with cholesterol-loaded cyclodextrins or cyclodextrins prior to cryopreservation: effects on post-thaw in vitro sperm quality of sperm cryopreserved in different freezing extenders.

    OpenAIRE

    BLANCH TORRES, EVA

    2016-01-01

    [EN] Cryopreserved boar sperm is not used extensively for artificial insemination due to poor fertility rates of the sperm after freezing and thawing. The sperm membrane is damaged when cooled from body temperature to 5 ºC (cold shock), as well as during the freeze-thaw process. Increasing the cholesterol content of boar sperm membranes could increase their post-thaw survival, similarly to other species that are cold shock sensitive. Cholesterol can be easily added to sperm membranes using ch...

  6. Effect of chilling duration on post-thaw characteristics of sperm from the North American bison (Bison bison).

    Science.gov (United States)

    Krishnakumar, S; Whiteside, D; Dance, A; Elkin, B; Thundathil, J

    2013-08-01

    The objective of this study was to determine the duration for which sperm from the North American bison (Bison bison) could be chilled prior to being cryopreserved, without compromising post- thaw sperm quality. This would permit transport of samples collected remotely, to the laboratory (at 4°C) for cryopreservation. Epididymal sperm from plains bison (n = 11) and ejaculated sperm from wood bison (n = 3) were collected, extended and held at 4°C for extended periods of time. At intervals, an aliquot was cryopreserved. Post-thaw sperm motion characteristics were evaluated by computer assisted sperm analysis. Representative plains bison sperm samples (n = 3) were evaluated for their in vitro fertilizing ability in a heterologous system using bovine oocytes. There was no statistical difference in total and progressive motility of plains bison epididymal sperm when cryopreserved after chilling for 24, 48 or 72 h. For wood bison ejaculated sperm, there was no difference in total and progressive motility for sperm cryopreserved following 24 or 48 h of chilling. However, one of the three bulls showed significantly poorer fertilization (based on cleavage rate) with sperm chilled for 72 compared to 24 and 48 h prior to freezing. In conclusion, plains bison epididymal sperm can be chilled for 72 h and wood bison ejaculated sperm can be chilled for at least 48 h prior to cryopreservation without compromising post-thaw sperm motility, while heterologous in vitro fertilization (IVF) assay indicated a between-bull variation in the in vitro fertilizing ability of sperm chilled for an extended duration before cryopreservation. © 2013 Blackwell Verlag GmbH.

  7. Dissolved organic matter composition of winter flow in the Yukon River basin: Implications of permafrost thaw and increased groundwater discharge

    Science.gov (United States)

    O'Donnell, Jonathan A.; Aiken, George R.; Walvoord, Michelle Ann; Butler, Kenna

    2012-01-01

    Groundwater discharge to rivers has increased in recent decades across the circumpolar region and has been attributed to thawing permafrost in arctic and subarctic watersheds. Permafrost-driven changes in groundwater discharge will alter the flux of dissolved organic carbon (DOC) in rivers, yet little is known about the chemical composition and reactivity of dissolved organic matter (DOM) of groundwater in permafrost settings. Here, we characterize DOM composition of winter flow in 60 rivers and streams of the Yukon River basin to evaluate the biogeochemical consequences of enhanced groundwater discharge associated with permafrost thaw. DOC concentration of winter flow averaged 3.9 ± 0.5 mg C L−1, yet was highly variable across basins (ranging from 20 mg C L−1). In comparison to the summer-autumn period, DOM composition of winter flow had lower aromaticity (as indicated by specific ultraviolet absorbance at 254 nm, or SUVA254), lower hydrophobic acid content, and a higher proportion of hydrophilic compounds (HPI). Fluorescence spectroscopy and parallel factor analysis indicated enrichment of protein-like fluorophores in some, but not all, winter flow samples. The ratio of DOC to dissolved organic nitrogen, an indicator of DOM biodegradability, was positively correlated with SUVA254 and negatively correlated with the percentage of protein-like compounds. Using a simple two-pool mixing model, we evaluate possible changes in DOM during the summer-autumn period across a range of conditions reflecting possible increases in groundwater discharge. Across three watersheds, we consistently observed decreases in DOC concentration and SUVA254 and increases in HPI with increasing groundwater discharge. Spatial patterns in DOM composition of winter flow appear to reflect differences in the relative contributions of groundwater from suprapermafrost and subpermafrost aquifers across watersheds. Our findings call for more explicit consideration of DOC loss and stabilization

  8. Effect of citrate ions on the softening of root crops prepared with freeze-thaw impregnation of macerating enzymes.

    Science.gov (United States)

    Nakatsu, Sayaka; Shimoda, Mitsuya; Shibata, Kenya; Kajihara, Ryo; Ishihara, Masako; Sakamoto, Koji

    2014-03-01

    Freeze-thaw impregnation is a technique used for the rapid impregnation of substances into foodstuffs. Freeze-thaw impregnation with macerating enzymes has been applied to soften foodstuffs, while retaining their original shapes and flavors. In this study, we found that co-impregnation with citrate ions and macerating enzymes significantly facilitated the softening of root crops. When burdock roots were processed by the impregnating solution at pH 4.0-5.0, co-impregnated burdock roots exhibited 1/6-1/3 firmness values compared with burdock roots impregnated with only enzymes. The impregnation with citrate ions alone at pH 4.0 to 5.0 did not soften burdock roots. The firmness of burdock roots was positively correlated with the amount of water-insoluble calcium in the samples. The results suggested that the degradation of pectins by pectinolytic activities could promote contact with citrate to bridging-calcium ions interacting with the pectin chains. Therefore, the softening by the synergistic effect of citrate ions and macerating enzymes was related to the amount of pectins contained in root crops. That is, the synergistic effect was significant with burdock roots and carrots (from which 50% of polysaccharides are pectins) unlike with lotus rhizomes and bamboo shoots (from which 30% and 10% of polysaccharides are pectins, respectively). Freeze-thaw impregnation with macerating enzymes and citrate ions can be applied for the production of care foods which can be eaten without chewing. The softened products induce the pleasure of eating for consumers because their original shapes and flavors are retained. © 2014 Institute of Food Technologists®

  9. Soil Redox Conditions Are a Strong Determinant of Microbial Community Composition and the Fate of Carbon Following Permafrost Thaw.

    Science.gov (United States)

    Bottos, E. M.; Bramer, L.; Kim, Y. M.; Fansler, S.; Nicora, C.; Zink, E.; Chu, R. K.; Tfaily, M. M.; Metz, T. O.; Jansson, J.; Stegen, J.

    2016-12-01

    Permafrost-affected soils contain enormous stocks of carbon, which are becoming increasingly available to microbial transformation as permafrost regions warm; however, how this warming will influence the permafrost microbiome and the transformation of soil carbon remains unclear. We hypothesize that the redox conditions that arise following permafrost thaw will dictate the structure and function of the microbial community, and strongly influence the nature of carbon transformations. To examine this, permafrost-affected soils from Caribou Poker Creek Research Watershed, Alaska were incubated at 4 °C under aerobic and anaerobic conditions for periods of 9 and 94 days. Over the incubation period, rates of CO2 and CH4 production were measured by gas chromatography, shifts in microbial community structure were characterized by 16S rRNA gene sequencing, and changes in metabolite and organic matter composition were analyzed by GC-MS and ESI-FTICR MS, respectively. CO2 production rates were significantly higher in aerobic treatments in 9-day and 94-day incubations, by 3-times and 12-times, respectively. Rates of CH4 production were not significantly different between treatments in 9-day incubations, but were 1.6-times higher in anaerobic treatments in 94-day incubations. The community composition remained largely unchanged in the incubated samples, with the exception of the 94-day aerobic incubations, which shifted strongly to become dominated by a single OTU, Rhodoferax ferrireducens. Metabolite profiles also shifted most strongly in the 94-day aerobic incubations, with the abundance of phosphorylated carbon compounds overrepresented in these samples. This work suggests that the redox conditions that arise following permafrost thaw will be a strong determinant of community composition and will govern the ultimate fate of carbon stocks in permafrost-affected soils. Our results are currently being integrated with numerical models aimed at predicting the coupled microbiome

  10. Temporal monitoring of the soil freeze-thaw cycles over snow-cover land by using off-ground GPR

    KAUST Repository

    Jadoon, Khan

    2013-07-01

    We performed off-ground ground-penetrating radar (GPR) measurements over a bare agricultural field to monitor the freeze-thaw cycles over snow-cover. The GPR system consisted of a vector network analyzer combined with an off-ground monostatic horn antenna, thereby setting up an ultra-wideband stepped-frequency continuous-wave radar. Measurements were performed during nine days and the surface of the bare soil was exposed to snow fall, evaporation and precipitation as the GPR antenna was mounted 110 cm above the ground. Soil surface dielectric permittivity was retrieved using an inversion of time-domain GPR data focused on the surface reflection. The GPR forward model used combines a full-waveform solution of Maxwell\\'s equations for three-dimensional wave propagation in planar layered media together with global reflection and transmission functions to account for the antenna and its interactions with the medium. Temperature and permittivity sensors were installed at six depths to monitor the soil dynamics in the top 8 cm depth. Significant effects of soil dynamics were observed in the time-lapse GPR, temperature and permittivity data and in particular freeze and thaw events were clearly visible. A good agreement of the trend was observed between the temperature, permittivity and GPR time-lapse data with respect to five freeze-thaw cycles. The GPR-derived permittivity was in good agreement with sensor observations. The proposed method appears to be promising for the real-time mapping and monitoring of the frozen layer at the field scale. © 2013 IEEE.

  11. Spatial Variability of L-Band Brightness Temperature during Freeze/Thaw Events over a Prairie Environment

    Directory of Open Access Journals (Sweden)

    Alexandre Roy

    2017-08-01

    Full Text Available Passive microwave measurements from space are known to be sensitive to the freeze/thaw (F/T state of the land surface. These measurements are at a coarse spatial resolution (~15–50 km and the spatial variability of the microwave emissions within a pixel can have important effects on the interpretation of the signal. An L-band ground-based microwave radiometer campaign was conducted in the Canadian Prairies during winter 2014–2015 to examine the spatial variability of surface emissions during frozen and thawed periods. Seven different sites within the Kenaston soil monitoring network were sampled five times between October 2014 and April 2015 with a mobile ground-based L-band radiometer system at approximately monthly intervals. The radiometer measurements showed that in a seemingly homogenous prairie landscape, the spatial variability of brightness temperature (TB is non-negligible during both frozen and unfrozen soil conditions. Under frozen soil conditions, TB was negatively correlated with soil permittivity (εG. This correlation was related to soil moisture conditions before the main freezing event, showing that the soil ice volumetric content at least partly affects TB. However, because of the effect of snow on L-Band emission, the correlation between TB and εG decreased with snow accumulation. When compared to satellite measurements, the average TB of the seven plots were well correlated with the Soil Moisture Ocean Salinity (SMOS TB with a root mean square difference of 8.1 K and consistent representation of the strong F/T signal (i.e., TB increases and decreases when soil freezing and thawing, respectively. This study allows better quantitative understanding of the spatial variability in L-Band emissions related to landscape F/T, and will help the calibration and validation of satellite-based F/T retrieval algorithms.

  12. Using dissolved organic matter age and composition to detect permafrost thaw in boreal watersheds of interior Alaska

    Science.gov (United States)

    O'Donnell, Jonathan A.; Aiken, George R.; Walvoord, Michelle Ann; Raymond, Peter A.; Butler, Kenna D.; Dornblaser, Mark M.; Heckman, Katherine

    2014-01-01

    Recent warming at high latitudes has accelerated permafrost thaw, which can modify soil carbon dynamics and watershed hydrology. The flux and composition of dissolved organic matter (DOM) from soils to rivers are sensitive to permafrost configuration and its impact on subsurface hydrology and groundwater discharge. Here, we evaluate the utility of DOM composition and age as a tool for detecting permafrost thaw in three rivers (Beaver, Birch, and Hess Creeks) within the discontinuous permafrost zone of interior Alaska. We observed strong temporal controls on Δ14C content of hydrophobic acid isolates (Δ14C-HPOA) across all rivers, with the most enriched values occurring during spring snowmelt (75 ± 8‰) and most depleted during winter flow (−21 ± 8‰). Radiocarbon ages of winter flow samples ranged from 35 to 445 yr BP, closely tracking estimated median base flow travel times for this region (335 years). During spring snowmelt, young DOM was composed of highly aromatic, high molecular-weight compounds, whereas older DOM of winter flow had lower aromaticity and molecular weight. We observed a significant correlation between Δ14C-HPOA and UV absorbance coefficient at 254 nm (α254) across all study rivers. Usingα254 as an optical indicator for Δ14C-HPOA, we also observed a long-term decline in α254 during maximum annual thaw depth over the last decade at the Hess Creek study site. These findings suggest a shift in watershed hydrology associated with increasing active layer thickness. Further development of DOM optical indicators may serve as a novel and inexpensive tool for detecting permafrost degradation in northern watersheds.

  13. The effect of vegetation type and fire on permafrost thaw: An empirical test of a process based model

    Science.gov (United States)

    Thierry, Aaron; Estop-Aragones, Cristian; Fisher, James; Hartley, Iain; Murton, Julian; Phoenix, Gareth; Street, Lorna; Williams, Mathew

    2015-04-01

    As conditions become more favourable for plant growth in the high latitudes, most models predict that these areas will take up more carbon during the 21st century. However, vast stores of carbon are frozen in boreal and arctic permafrost, and warming may result in some of this carbon being released to the atmosphere. The recent inclusion of permafrost thaw in large-scale model simulations has suggested that the permafrost feedback could potentially substantially reduce the predicted global net uptake of carbon by terrestrial ecosystems, with major implications for the rate of climate change. However, large uncertainties remain in predicting rates of permafrost thaw and in determining the impacts of thaw in contrasting ecosystems, with many of the key processes missing from carbon-climate models. The role that different plant communities play in insulating soils and protecting permafrost is poorly quantified, with key groups such as mosses absent in many models. But it is thought that they may play a key role in determining permafrost resilience. In order to test the importance of these ecological processes we use a new specially acquired dataset from sites in the Canadian arctic to develop, parameterise and evaluate a detailed process-based model of vegetation-soil-permafrost interactions which includes an insulating moss understory. We tested the sensitivity of modelled active layer depth to a series of factors linked to fire disturbance, which is common in boreal permafrost areas. We show how simulations of active layer depth (ALD) respond to removals of (i) vascular vegetation, (ii) moss cover, and (iii) organic soil layers. We compare model responses to observed patterns from Canada. We also describe the sensitivity of our modelled ALD to changes in temperature and precipitation. We found that four parameters controlled most of the sensitivity in the modelled ALD, linked to conductivity of organic soils and mosses.

  14. Dose-dependent effects of homologous seminal plasma on motility and kinematic characteristics of post-thaw stallion epididymal spermatozoa.

    Science.gov (United States)

    Neuhauser, S; Dörfel, S; Handler, J

    2015-05-01

    Preservation of epididymal spermatozoa is important to save genetic material of endangered species and breeds, or in case of unexpected injury, which will end the breeding career of valuable sires. Seminal plasma (SP) influences sperm quality in a dose-dependent manner and its addition to preserved semen immediately before insemination may be beneficial for sperm fertility. Increased plasma membrane stability of epididymal spermatozoa reduces freezing injury of cells, and the addition of SP after freezing and thawing might have activating and protecting effects on spermatozoa within the female genital tract. In this study, epididymal spermatozoa were harvested by retrograde flush of the epididymal cauda immediately after routine castration and frozen. Seminal plasma was collected from other six stallions. Homologous SP (SP from the same species, but from a different animal) was added to frozen-thawed epididymal spermatozoa at concentrations of 0, 5, 20, 50 and 80% SP. Addition of SP increased sperm motility and influenced kinematic values in a dose-dependent manner (p sperm motility among SP from six different donor stallions regardless of the concentrations of SP (p > 0.05). Total and progressive motility of ten frozen-thawed epididymal spermatozoa samples collected from different stallions after dilution with extender and 5, 20, 50 or 80% SP differed significantly (p epididymal spermatozoa immediately improved motility in a dose-dependent manner regardless of semen quality of SP donor stallions. This might positively influence fertility when SP is added before insemination. Moreover, there seems to be a threshold level of SP concentration for optimal improvement of sperm motility. © 2015 American Society of Andrology and European Academy of Andrology.

  15. Permafrost thaw in upland catchments of central Alaska: groundwater connection and landscape evolution as discerned from U isotopes and dissolved organic carbon

    Science.gov (United States)

    Ewing, S. A.; O'Donnell, J. A.; Paces, J. B.; Jorgenson, M. T.; Kanevskiy, M. Z.; Harden, J. W.; Aiken, G.; Striegl, R. G.

    2009-12-01

    Permafrost thaw mobilizes carbon and transforms hydrologic flowpaths, with the potential for large feedback effects on climate. Permafrost thaw also results in poorly quantified geomorphic effects that depend on ground ice volumes, sediment texture, and thermal effects of thaw waters. Here we use 234U/238U activity ratios (ARs) to indicate the influence of deep groundwater following fire-induced permafrost thaw in geologically distinct upland catchments in central Alaska. The 234U/238U AR in water or ice increases as a function of contact time with sediment, at a rate that depends on sediment and water U concentrations, surface area, and sediment/water ratio. Combining U series data with solute concentrations for soil porewaters, shallow permafrost and surface streams, we make inferences about the influence of recent thaw (last 100 y) on landscapes, hydrology and dissolved organic carbon (DOC) dynamics in central Alaska. In a loess-dominated catchment where ice-rich silt is present to depths of up to 25 m, the depth of fire-induced thaw is limited to ~50 cm. DOC concentrations in surface waters and soil porewaters showed little seasonal or spatial variation (40±7 ppm in spring and fall 2008) and were positively correlated with solutes indicating mineral contact in fall 2008. In soil porewaters, surface waters and upper permafrost (2 m depth), 234U/238U ARs (1.15-1.27) were lower than those in deep permafrost (up to 1.55) and groundwater (1.54), suggesting no deep thaw or connection to deeper groundwater regardless of time-since-fire. Shallow thaw and soil wetting allowed for post-fire recovery of shallow permafrost and hence black spruce communities on the order of 100 y. Yet we observed landscape responses to thaw including thermokarst pits and channels, bank collapse, and stream incision, suggesting longer-term landscape equilibration. By contrast, in a colluvium-dominated catchment, gravelly textures allow better drainage of thaw water, resulting in deep thaw

  16. Effect of permafrost thawing on organic carbon and trace element colloidal speciation in the thermokarst lakes of western Siberia

    Directory of Open Access Journals (Sweden)

    O. S. Pokrovsky

    2011-03-01

    Full Text Available To examine the mechanisms of carbon mobilization and biodegradation during permafrost thawing and to establish a link between organic carbon (OC and other chemical and microbiological parameters in forming thermokarst (thaw lakes, we studied the biogeochemistry of OC and trace elements (TEs in a chronosequence of small lakes that are being formed due to permafrost thawing in the northern part of western Siberia. Twenty lakes and small ponds of various sizes and ages were sampled for dissolved and colloidal organic carbon, metals and culturable heterotrophic bacterial cell number. We observed a sequence of ecosystems from peat thawing and palsa degradation due to permafrost subsidence in small ponds to large, km-size lakes that are subject to drainage to, finally, the khasyrey (drained lake formation. There is a systematic evolution of both total dissolved and colloidal concentration of OC and TEs in the lake water along with the chronosequence of lake development that may be directly linked to the microbial mineralization of dissolved organic matter and the liberation of the inorganic components (Fe, Al, and TEs from the organo-mineral colloids.

    In this chronosequence of lake development, we observed an apparent decrease in the relative proportion of low molecular weight <1 kDa (1 kDa ~ 1 nm OC concentration along with a decrease in the concentration of total dissolved (<0.45 μm OC. This decrease was accompanied by an increase in the small size organic ligands (probably autochthonous exometabolites produced by the phytoplankton and a simultaneous decrease in the proportion of large-size organic (humic complexes of allochthonous (soil origin. This evolution may be due to the activity of heterotrophic bacterioplankton that use allochthonous organic matter and dissolved nutrients originating from peat lixiviation. Most insoluble TEs demonstrate a systematic decrease in concentration during filtration (5 μm, 0.45 μm exhibiting a similar

  17. Twin pregnancy obtained with frozen-thawed embryos after in vitro maturation in a patient with polycystic ovarian syndrome

    OpenAIRE

    Godin, P. A.; Gaspard, Olivier; Thonon, Fabienne; Jouan, Caroline; Wijzen, F.; Dubois, Michel; Foidart, Jean-Michel

    2003-01-01

    Purpose: A twin pregnancy was obtained in a patient with polycystic ovary syndrome after the transfer of three in vitro maturation-derived day 3 embryos that has been frozen and thawed. Methods: The patient had received mild hMG stimulation followed by hCG injection. After culture for 24 - 48 h, mature oocytes were fertilized by ICSI. Embryos were cultured until day 3; supernumerary embryos were cryopreserved using a slow protocol. Results: Among 15 nonatretic oocytes, 9 matured, 8 were ferti...

  18. Cryopreservation of turkey semen: effect of breeding line and freezing method on post-thaw sperm quality, fertilization, and hatching.

    Science.gov (United States)

    Long, Julie A; Purdy, Phillip H; Zuidberg, Kees; Hiemstra, Sipke-Joost; Velleman, Sandra G; Woelders, Henri

    2014-06-01

    Cryopreservation methods for poultry semen are not reliable for germplasm preservation, especially for turkeys, where fertility rates from frozen/thawed semen are particularly low. The objective was to evaluate cryopreservation methods for effectiveness in promoting cryosurvival and post-thaw function of sperm from five turkey lines: one commercial line and four research (RBC1; E; RBC2; F) lines from Ohio State University (OSU). The model for cryopreservation was set up as a 2×2×2×5 design for cryoprotectant (glycerol or dimethylacetamide (DMA)), cryopreservation medium (Lake or ASG), method of dilution (fixed dilution volume versus fixed sperm concentration) and turkey line, respectively. The final cryoprotectant concentrations were 11% glycerol or 6% DMA. Thawed sperm were evaluated for plasma membrane integrity and quality, motility, acrosome integrity and, after artificial insemination, for egg fertility and hatchability. Commercial turkey hens were used for all fertility trials, regardless of semen source. Turkey sperm frozen with glycerol exhibited higher membrane integrity and membrane quality upon thawing than turkey sperm frozen with DMA although no differences in total motility, and only minimal differences in progressive motility, were detected among the eight cryopreservation treatments. Within line, fertility was affected by cryoprotectant, medium and dilution method, where the overall highest percentages of fertile, viable embryos (Day 7) occurred for the DMA/ASG/fixed sperm concentration method, while high percentages (15.8-31.5%) of fertile, non-viable embryos (Day 1-6) were observed for multiple cryopreservation methods, including two glycerol treatments. From a single insemination, the duration of true and viable fertility in all lines was 10-13 weeks and 9-10 weeks, respectively. The duration of hatchability was 4-6 weeks after insemination for four of the turkey lines. The highest percentage of viable embryos was observed for the commercial

  19. Micro-fractures produced in the Cadalso de los Vidrios granite (Madrid) subjected to Freeze-Thaw Durability Testing

    Science.gov (United States)

    Freire-Lista, D. M.; Varas-Muriel, M. J.; Fort, R.

    2012-04-01

    A specific leucogranite (fine to medium grain sized) from Cadalso de los Vidrios, Madrid, Spain, from where it takes the name of the stone variety, which is a traditional heritage building material used in Central Spain, was subjected to freezing-thaw durability tests or accelerated artificial ageing tests (according to Spanish standard EN 12371:2001) to assess its durability by means of ultrasonic velocity measurements (a non-destructive technique), and optical and fluorescence petrography using a polarized optical microscope (destructive technique), both techniques used before, during and after laboratory ageing tests, or in other words, what is determined is the improvement or deterioration in some properties. The measurement of the ultrasonic velocity in the leucogranite cubic test specimens along the freezing-thaw cycles shown that the velocity diminishes with the number of cycles, in relation to the decay that the stones were experiencing. This deterioration can be observed by the loss of crystalline minerals in the surface of the analyzed samples and by the micro-fractures appearance up to one centimeter deep, which have been detected by the petrographic techniques previously mentioned. The images taken by means of the fluorescence microscope clearly show the micro-fractures generated during the durability test. These images have been processed and analyzed by the UTHSCSA Image Tool program with the purpose of being able to quantify the degree of decay that this type of crystalline materials undergone, when subjected to a number of freezing-thaw test cycles. It is therefore an effective, reliable and complementary technique to that of the petrography analysis, both optical and fluorescence ones. In the first cycles of the ageing test, the micro-fractures propagate along crystals edges and during the last cycles of the test, intracrystalline micro-fractures are generated, which are developed in different ways depending on the mineralogy of the crystals. Thus

  20. Evaluation, including effects of storage and repeated freezing and thawing, of a method for measurement of urinary creatinine

    DEFF Research Database (Denmark)

    Garde, A H; Hansen, Åse Marie; Kristiansen, J

    2003-01-01

    The aims of this study were to elucidate to what extent storage and repeated freezing and thawing influenced the concentration of creatinine in urine samples and to evaluate the method for determination of creatinine in urine. The creatinine method was based on the well-known Jaffe's reaction.......1 mmol/L), was 0.3 mmol/L, and the recovery of a certified reference material was 97%. The relative precision at 3.15 mmol/L was 2.3%. It was concluded that the method is appropriate for measurement of urinary creatinine....

  1. The positive net radiative greenhouse gas forcing of increasing methane emissions from a thawing boreal forest-wetland landscape.

    Science.gov (United States)

    Helbig, Manuel; Chasmer, Laura E; Kljun, NatasCha; Quinton, William L; Treat, Claire C; Sonnentag, Oliver

    2017-06-01

    At the southern margin of permafrost in North America, climate change causes widespread permafrost thaw. In boreal lowlands, thawing forested permafrost peat plateaus ('forest') lead to expansion of permafrost-free wetlands ('wetland'). Expanding wetland area with saturated and warmer organic soils is expected to increase landscape methane (CH4 ) emissions. Here, we quantify the thaw-induced increase in CH4 emissions for a boreal forest-wetland landscape in the southern Taiga Plains, Canada, and evaluate its impact on net radiative forcing relative to potential long-term net carbon dioxide (CO2 ) exchange. Using nested wetland and lan