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Sample records for thawed human femora

  1. The error of midshaft cross-sectional location on human femora

    Czech Academy of Sciences Publication Activity Database

    Sládek, Vladimír; Berner, M.; Friedl, L.

    2008-01-01

    Roč. 135, S46 (2008), s. 195-196 ISSN 0002-9483. [Annual Meeting of the American Association of Physical Anthropologists /77./. 09.04.2008-12.04.2008, Columbus, Ohio] Institutional research plan: CEZ:AV0Z60930519 Keywords : human femora * Central Europe Subject RIV: AC - Archeology, Anthropology, Ethnology http://www3.interscience.wiley.com/cgi-bin/fulltext/117908222/PDFSTART

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

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    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.

  3. Structure and composition of the Trinil femora: functional and taxonomic implications.

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    Ruff, Christopher B; Puymerail, Laurent; Macchiarelli, Roberto; Sipla, Justin; Ciochon, Russell L

    2015-03-01

    The original hominin femur (Femur I) and calotte discovered at Trinil, Java by Eugene Dubois in 1891/1892 played a key role in the early history of human paleontology by purportedly demonstrating the contemporaneity of archaic cranial form with modern human erect (bipedal) posture. On this basis, both specimens were subsequently assigned to Pithecanthropus erectus, later transferred to Homo erectus. However, chronological and phylogenetic links between the two have been questioned from the beginning. Four additional hominin partial femora (Femora II-V) from Trinil were subsequently described but have played a relatively minor part in evolutionary scenarios. Here we present the results of a new analysis of structural and density characteristics of the Trinil femora obtained using computed tomography. Trinil Femur I shows none of the characteristics typical of early Homo femora from elsewhere in Asia or Africa, including a relatively long neck, increased mediolateral bending rigidity of the mid-proximal shaft, or a low position of minimum mediolateral breath on the shaft. In contrast, Femora II-V all demonstrate features that are more consistent with this pattern. In addition, material density distributions within the specimens imply more recent and less complete fossilization of Femur I than Femora II-V. Thus, it is very likely that Trinil Femur I derives from a much more recent time period than the calotte, while the less famous and less complete Femora II-V may represent H. erectus at Trinil. The morphological variation within the Trinil femora can be attributed to broader changes in pelvic morphology occurring within the Homo lineage between the Early and late Middle Pleistocene. Copyright © 2015. Published by Elsevier Ltd.

  4. Stress fractures of the femora in soldiers

    International Nuclear Information System (INIS)

    Meurman, K.O.A.; Somer, K.; Lamminen, A.

    1981-01-01

    Amongst 936 stress fractures found in soldiers, there were 58 in the femora (6%); of these 31 were in the neck and 27 in the shaft. Two were bilateral, and two patients had other stress fractures. Three displacements were found in the necks. In the shaft, 20 fractures were proximal, four were in the middle third and three in the distal third. In the latter group, it is necessary to differentiate from a sarcoma. CT is a new aid in this respect. Sport in highly motivated individuals appears to contribute particularly to fractures of the shaft. The symptoms from these fractures are relatively mild. (orig.) [de

  5. Effects of the freezing and thawing process on biomechanical properties of the human skull.

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    Torimitsu, Suguru; Nishida, Yoshifumi; Takano, Tachio; Koizumi, Yoshinori; Hayakawa, Mutsumi; Yajima, Daisuke; Inokuchi, Go; Makino, Yohsuke; Motomura, Ayumi; Chiba, Fumiko; Iwase, Hirotaro

    2014-03-01

    The aim of this study was to determine if biomechanical investigations of skull samples are reliable after skulls have been subjected to a freezing and thawing process. The skulls were obtained from 105 Japanese cadavers (66 males, 39 females) of known age that were autopsied in our department between October 2012 and June 2013. We obtained bone specimens from eight sites (four bilaterally symmetrical pairs) of each skull and measured the mass of each specimen. They were then classified into three groups (A, B, C) based on the duration of freezing of the experimental samples. The left-side samples were subjected to frozen storage (experimental group). The corresponding right-side samples were their controls. Bending tests were performed on the controls immediately after they were obtained. The experimental samples were preserved by refrigeration at -20 °C for 1 day (group A), 1 month (group B), or 3 months (group C). Following refrigeration, these samples were placed at 37 °C to thaw for 1 h and then were subjected to bending tests using a three-point-bending apparatus attached to a Handy force gauge. The device recorded the fracture load automatically when the specimen fractured. Statistical analyses revealed that there were no significant differences in sample fracture loads between the frozen preserved/thawed samples and the unfrozen controls for each of the cryopreservation intervals. We eliminated any possible sample mass bias by using controls from the same skull in each case. The results suggest that the freezing/thawing process has little effect on the mechanical properties of human skulls. Thus, frozen storage for up to 3 months is a good method for preserving human skulls. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  6. Freezing and thawing effects on fat, protein, and lactose levels of human natural milk administered by gavage and continuous infusion

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    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.

  7. 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.

  8. 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

  9. Liquid nitrogen vapor is comparable to liquid nitrogen for storage of cryopreserved human sperm: evidence from the characteristics of post-thaw human sperm.

    Science.gov (United States)

    Hu, Jingmei; Zhao, Shidou; Xu, Chengyan; Zhang, Lin; Lu, Shaoming; Cui, Linlin; Ma, Jinlong; Chen, Zi-Jiang

    2015-11-01

    To compare the differences in the characteristics of post-thaw human sperm after storage in either liquid nitrogen (LN2; -196 °C) or LN2 vapor (-167 °C). Experimental study. University hospital. Thirty healthy volunteers who agreed to donate their normal semen samples for infertility or research were included in the study. Semen samples (n = 30) were divided into eight aliquots and frozen. Four aliquots of each human semen sample were stored in LN2 (-196 °C), and the other four aliquots were stored in LN2 vapor (-167 °C). After 1, 3, 6, or 12 months, samples were thawed and analyzed. The motility was evaluated by the manual counting method. The viability was estimated by eosin staining. The morphology was analyzed by Diff-Quik staining. The sperm DNA integrity was determined with acridine orange fluorescent staining, and acrosin activity was assayed by the modified Kennedy method. The characteristics of post-thaw human sperm, including motility, viability, morphology, DNA integrity, and acrosin activity, showed no significant difference between LN2 and LN2 vapor storage for the different time periods. LN2 vapor was comparable to LN2 in post-thaw sperm characteristics, suggesting that LN2 vapor may be substituted for LN2 for the long-term storage of human sperm. Copyright © 2015 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

  10. A STUDY ON FEMORAL ANTEVERSION IN ADULT DRY FEMORA OF SOUTH INDIAN POPULATION

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    Sushma Korukonda

    2017-01-01

    Full Text Available BACKGROUND Femoral Neck Anteversion (FNA is an important parameter for diagnosis of gait abnormality in children, risk of various congenital and acquired orthopaedic disorders as well as corrective osteotomy and hip arthroplasty. Femoral anteversion is the lateral rotation of the neck of the femur to the long axis of its shaft. Variability in FNA has been reported and is due to torsional forces applied on femur during development. The aim of this study was to estimate the angle of anteversion of femur in both genders on both sides. The present study was an attempt to provide baseline data of FNA in South Indian population, in particular, Andhra Pradesh. MATERIALS AND METHODS The study was conducted mechanically on 70 dried adult unpaired human femora, i.e. 48 male and 22 female bones. The Kingsley Olmsted 1 method was used for the study and the data was analysed. Statistical analysis - Statistical analysis was done using student unpaired ‘t’ test. The data was analysed using GraphPad Prism 5.0 (Free Trial Version. RESULTS Out of the 70 femora undertaken, mean value of FNA obtained in male is 15.95, 14.1 on right and 17.8 on left sides and in female it is 19.2, 21.8 on right and 16.6 on left side. Statistical analysis revealed significant (p < 0.05 greater average anteversion in female bones and right-left variations being greater on the left side. CONCLUSION In the present study, the mean FNA was 17.8 deg. There was a gender variation for the FNA values in the population studied with females showing higher value than the male with a statistically significant difference. The reason for the difference obtained could be the small sample size of female femora due to the rarity of the donated female bodies. The value was higher on the left side than the right; 50% of the femora had the range of 16 - 25 deg of FNA. The overall mean of femoral anteversion determined is very much different from the studies in various regions in India.

  11. Improved recovery of post-thaw motility and vitality of human spermatozoa cryopreserved in the presence of dithiothreitol.

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    Rao, B; David, G

    1984-10-01

    Semen was collected in the laboratory from nine healthy donors. The concentrations and the percentages of live and motile spermatozoa in all semen samples were within the normal range. Each sample was diluted with citrate-egg yolk-glycerol medium with and without 5 mM dithiothreitol (DTT). Samples were frozen in liquid nitrogen vapor (-70 degrees C) for 7 min and subsequently stored in liquid nitrogen. The effect of DTT in cryopreservation of sperm was determined by comparing percentage of motile and live spermatozoa between controls and DTT-treated post-thaw samples. Percentage of motile spermatozoa was determined by two techniques, laser Doppler velocimetry (LDV) and light microscopy. The percentage of live spermatozoa was measured by microscopic evaluation after staining with eosin-nigrosin. It was shown that the addition of DTT to the freezing medium significantly improved the recovery of motile and live spermatozoa in the post-thaw samples. The mean motility recovery, as measured by LDV, was 44.9% in the controls as compared to 73.9% in the DTT-treated samples. Similarly the mean recovery of live spermatozoa in the controls and DTT-treated samples was 66.5 and 86.6%, respectively. Based on these results, a new hypothesis implicating lipid peroxidation in cryoinjury is proposed. It is also suggested that the use of DTT in the freezing medium may offer an advantage over the commonly used techniques of human sperm cryopreservation.

  12. Melatonin affects membrane integrity, intracellular reactive oxygen species, caspase3 activity and AKT phosphorylation in frozen thawed human sperm.

    Science.gov (United States)

    Najafi, Atefeh; Adutwum, Emmanuel; Yari, Abazar; Salehi, Ensieh; Mikaeili, Saideh; Dashtestani, Fariba; Abolhassani, Farid; Rashki, Leila; Shiasi, Setareh; Asadi, Ebrahim

    2018-04-01

    Cryopreservation is known to induce oxidative stress in spermatozoa. Although melatonin has powerful antioxidant properties, little is known about its effects on human sperm quality during cryopreservation. The present study was undertaken to investigate the effects of melatonin treatment on human sperm parameters essential for fertilization. We first evaluated the effects of various concentrations of melatonin (0-15 mM) on human sperm parameters such as motility, viability and levels of intracellular reactive oxygen species during cryopreservation in order to identify an optimal dose with the greatest effects for further studies. Liquefied semen samples were then divided into three aliquots: cryopreserved without melatonin (control), cryopreserved with 3 mM melatonin and fresh groups. After being thawed, samples were evaluated for motility, viability, membrane integrity, intracellular reactive oxygen species levels, caspase-3 activity and AKT phosphorylation. Treatment of spermatozoa with the various concentrations of melatonin significantly increased their motility and viability and decreased their intracellular reactive oxygen species levels compared with the control group. The optimal melatonin concentration (3 mM) significantly decreased the intracellular reactive oxygen species levels, caspase-3 activity and the percentage of both dead and apoptotic-like sperm cells and increased the vitality, progressive motility and total motility and AKT phosphorylation compared with the control group. Thus, melatonin exerts protective effects against cryodamage during human spermatozoa cryopreservation and may exert its effects via the PI3K/AKT signaling pathway.

  13. A pragmatic RCT of conventional versus increased concentration sucrose in freezing and thawing solutions for human embryos

    OpenAIRE

    Wood, M. J.; Mollison, J.; Harrild, K.; Ferguson, E.; McKay, T.; Srikantharajah, A.; Bell, L.; Bhattacharya, S.

    2011-01-01

    BACKGROUND Intact frozen-thawed embryos have a greater potential than damaged embryos to establish successful pregnancies. This study aimed to determine whether elevated concentrations of sucrose during freezing would increase the proportion of patients with ≥50% of embryos intact after thawing (primary outcome), and improve clinical outcome. METHODS In a two arm, parallel group, pragmatic trial, IVF/ICSI couples were randomized prospectively to have their supernumerary embryos frozen in a me...

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

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    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.

  15. A pragmatic RCT of conventional versus increased concentration sucrose in freezing and thawing solutions for human embryos.

    Science.gov (United States)

    Wood, M J; Mollison, J; Harrild, K; Ferguson, E; McKay, T; Srikantharajah, A; Bell, L; Bhattacharya, S

    2011-08-01

    Intact frozen-thawed embryos have a greater potential than damaged embryos to establish successful pregnancies. This study aimed to determine whether elevated concentrations of sucrose during freezing would increase the proportion of patients with ≥ 50% of embryos intact after thawing (primary outcome), and improve clinical outcome. In a two arm, parallel group, pragmatic trial, IVF/ICSI couples were randomized prospectively to have their supernumerary embryos frozen in a medium containing 0.1 M sucrose (control; n = 99) or 0.3 M sucrose (intervention; n = 102). More control (74/99) than intervention (63/102) couples had at least one embryo thawed (P = 0.07). Significantly more (P = 0.005) intervention (53/63) than control (45/74) couples had ≥ 50% of embryos intact. Freezing in a medium containing 0.3 M sucrose increased by 3.4-fold [95% confidence interval (CI) (1.45, 7.82)] the likelihood of a couple having ≥ 50% of their embryos intact. In the fresh cycle, live birth rate per transfer was similar in the control (35/95) and intervention (36/93) groups (P = 0.91). More control (19/63) than intervention (9/59) couples had a live birth after frozen embryo transfer (P = 0.08). When fresh and frozen cycles were combined, fewer intervention (n = 102) than control (n = 99) couples had at least one live birth (42 versus 53%). The difference in cumulative live birth rate was not significant [hazard ratio = 0.75, 95% CI (0.49, 1.13); P = 0.17]. Increasing the concentration of sucrose in the freezing medium improves embryo survival, but this is not reflected by increased cumulative birth rates. ISRCTN93314892.

  16. Triggering of final oocyte maturation with gonadotropin-releasing hormone agonist or human chorionic gonadotropin. Live birth after frozen-thawed embryo replacement cycles

    DEFF Research Database (Denmark)

    Griesinger, Georg; Kolibianakis, E M; Papanikolaou, E G

    2007-01-01

    . PATIENT(S): Patients under observation previously had been recruited into two concurrently performed, independent, randomized controlled trials (comparing hCG with GnRH-agonist for triggering final oocyte maturation in GnRH-antagonist multiple-dose protocols in normal responder patients) encompassing...... a total of 228 participants. Surplus embryos or oocytes at the pronuclear stage were cryopreserved in 53 patients after hCG administration and 32 patients after GnRH-agonist administration on the basis of patient choice, pronuclear/embryo availability, and local laws. INTERVENTION(S): Transfer of frozen......-thawed embryos. MAIN OUTCOME MEASURE(S): Live birth rate. RESULT(S): Thirty-one and 23 patients after administration of hCG and GnRH-agonist, respectively, started a frozen-embryo replacement cycle by September 2005, with 25 and 16 patients eventually undergoing at least one frozen-thawed ET. Live birth rate per...

  17. 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...

  18. Moisture controls decomposition rate in thawing tundra

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    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...

  19. Obstetric and perinatal outcomes after either fresh or thawed frozen embryo transfer: an analysis of 112,432 singleton pregnancies recorded in the Human Fertilisation and Embryology Authority anonymized dataset.

    Science.gov (United States)

    Maheshwari, Abha; Raja, Edwin Amalraj; Bhattacharya, Siladitya

    2016-12-01

    To explore obstetric and perinatal outcomes in singleton pregnancies occurring as a result of fresh and thawed frozen embryo transfer using anonymized Human Fertilisation and Embryology Authority data. Retrospective cohort study. Not applicable. Singleton births after IVF/intracytoplasmic sperm injection cycles in the United Kingdom (1991-2011). A total of 112,432 cycles (95,911 fresh and 16,521 frozen) were analyzed using multivariate logistic regression to explore associations between type of embryo transferred (frozen vs. fresh) and obstetric and perinatal outcomes. Relative risks (RRs) and their 99.5% confidence intervals (CIs) were calculated using Stata 14 MP, adjusting for potential confounders. Birth weight. The adjusted RR (99.5% CI) of low birth weight [0.73 (0.66-0.80)] and very low birth weight [0.78 (0.63-0.96)] were all lower after frozen embryo transfer; however, RR of having a high birth weight baby was higher [1.64 (1.53-1.76)]. There was no difference in RR of preterm birth [0.96 (0.88-1.03)], very preterm birth [0.86 (0.70-1.05)], and congenital anomalies [0.86 (0.73-1.01)]. The findings of low birth and very low birth weight after thawed frozen embryo transfer are consistent with the literature and provide reassurance regarding the outcome of pregnancies after frozen embryo transfers. However, they highlight the possibility of high birth weight in these babies. Because these results are based on observational data, further evidence from randomized, controlled trials is needed before elective cryopreservation of all embryos is practiced in preference to the current practice of transfer of fresh embryos. Crown Copyright © 2016. Published by Elsevier Inc. All rights reserved.

  20. 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.

  1. The Effects of Interlocking a Universal Hip Cementless Stem on Implant Subsidence and Mechanical Properties of Cadaveric Canine Femora.

    Science.gov (United States)

    Buks, Yonathan; Wendelburg, Kirk L; Stover, Susan M; Garcia-Nolen, Tanya C

    2016-02-01

    To determine if an interlocking bolt would limit subsidence of the biological fixation universal hip (BFX(®)) femoral stem under cyclic loading and enhance construct stiffness, yield, and failure properties. Ex vivo biomechanical study. Cadaveric canine femora (10 pairs). Paired femora implanted with a traditional stem or an interlocking stem (constructs) were cyclically loaded at walk, trot, and gallop loads while implant and bone motions were captured using kinematic markers and high-speed video. Constructs were then loaded to failure to evaluate failure mechanical properties. Implant subsidence was greater (P = .037) for the traditional implant (4.19 mm) than the interlocking implant (0.78 mm) only after gallop cyclic loading, and cumulatively after walk, trot, and gallop cyclic loads (5.20 mm vs. 1.28 mm, P = .038). Yield and failure loads were greater (P = .029 and .002, respectively) for the interlocking stem construct (1155 N and 2337 N) than the traditional stem construct (816 N and 1405 N). Version angle change after cyclic loading was greater (P = .020) for the traditional implant (3.89 degrees) than for the interlocking implant (0.16 degrees), whereas stem varus displacement at failure was greater (P = .008) for the interlocking implant (1.5 degrees) than the traditional implant (0.17 degrees). Addition of a stabilizing bolt enhanced construct stability and limited subsidence of a BFX(®) femoral stem. Use of the interlocking implant may decrease postoperative subsidence. However, in vivo effects of the interlocking bolt on osseointegration, bone remodeling, and stress shielding are unknown. © Copyright 2016 by The American College of Veterinary Surgeons.

  2. Dual-energy X-ray absorptiometry and force-plate analysis of gait in dogs with healed femora after leg-lengthening plate fixation

    International Nuclear Information System (INIS)

    Muir, P.; Markel, M.D.; Bogdanske, J.J.; Johnson, K.A.

    1995-01-01

    Dual-energy x-ray absorptiometry was used to measure bone mineral density of four regions in healed femora of nine dogs after fracture fixation with a leg-lengthening plate. Six to 85 months (mean, 46 months) after surgery, the bone mineral density of healed femora was not significantly different from the contralateral uninjured femora (P > .05; power = 0.8 at delta = 15%). Radiolucencies around the proximal screws, apparently associated with screw loosening, were seen on radiographic views of the healed femora of three dogs. In one of these dogs, one screw in the proximal metaphysis had broken. Force-plate analysis of gait was also performed on dogs at the time of bone mineral density measurement. Peak vertical force was decreased in the pelvic limb with the healed fracture compared with the contralateral unoperated limb (P < 0.05). Clinically apparent lameness in three dogs did not appear to be associated with altered bone mineral density and may have been caused by hip osteoarthritis, a nondisplaced hairline diaphyseal fracture, and screw loosening in conjunction with extensive post-traumatic soft tissue injury

  3. Are the dinosauromorph femora from the Upper Triassic of Hayden Quarry (New Mexico) three stages in a growth series of a single taxon?

    Science.gov (United States)

    Müller, Rodrigo T

    2017-01-01

    The lagerpetid Dromomeron romeri and the theropod Tawa hallae are two dinosauromorphs from the Norian (Upper Triassic) of the Chinle Formation, situated in New Mexico, USA. However, a recent study suggests the inclusion of the holotype of D. romeri (GR 218) and paratype (GR 155) and referred (GR 235) specimens of T. hallae in an ontogenetic series of a single species. The specimens GR 218 and GR 155 include just an isolated femur, while GR235 includes femora, pelvis and tail. The inclusion of the specimens in an unique ontogenetic series relies on the putative immature condition and plastic deformation of the specimen GR 218. However, as observed here, the disparity between the femora of D. romeri and T. hallae is considerably higher than those expected from the ontogenetic variance in dinosauromorphs. In addition, D. romeri shares an unique suite of traits with Dromomeron gigas, a species known from a mature specimen. Therefore, the high disparity between D. romeri and T. hallae, lack of traits shared solely between the three femora, and a suite of traits shared between D. romeri and D. gigas, precludes the inclusion of the three femora from Hayden Quarry in a growth series of a single taxon.

  4. 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.

  5. Assessment of the geometry of proximal femur for short cephalomedullary nail placement: An observational study in dry femora and living subjects

    Directory of Open Access Journals (Sweden)

    Devendra Pathrot

    2016-01-01

    Full Text Available Background: Intramedullary devices have increasingly become popular and are widely used for fixation of unstable intertrochanteric and subtrochanteric fractures as well. These implants have been designed taking into consideration the anthropometry of the western population whose anthropometry varies from those of other ethnic groups. This study was carried out to assess the geometry of proximal femur for the placement of short cephalomedullary nails in our subset of patients and suggest suitable design modifications based on these parameters. Materials and Methods: The study was conducted in the following three groups: (1 Anthropometric study of 101 adult human dry femora, (2 radiographs of the same femora, and (3 radiographs of the contralateral uninjured limb of 102 patients with intertrochanteric or subtrochanteric fractures. In Group 1, standard anthropometric techniques were used to measure neck shaft angle (NSA, minimal neck width (NW, trochanteric offset, and distance from the tip of greater trochanter (GT to the lower border of lesser trochanter on the femoral shaft axis (distance X. In Group 2 and 3, the NSA, minimal NW, NW at 130° and 135°, trochanteric shaft angle (TSA, trochanteric offset, distance X, distance between the tip of GT and the point where the neck axis crosses the line joining the tip of the GT to the lower border of the lesser trochanter on the femoral shaft axis (distance Y, and canal width at 10, 15, and 20 cm from tip of GT were measured on standard radiographs. The values obtained in these three groups were pooled to obtain mean values. Various parameters of commonly used short cephalomedullary nails available for fixation of pertrochanteric fractures were obtained. These were compared to the results obtained to suggest suitable modifications in the nail designs for our subset of patients. Results: The mean parameters observed were as follows: NSA 128.07° ± 4.97 (range 107°–141°, minimum NW 29.0 ± 2.8 mm

  6. Production of recombinant human growth hormone in Eschericia coli strain Origami and comparing freeze/ thaw and sonication methods for proteins extraction

    OpenAIRE

    marzieh savari; sayyed hamid Zarkesh-Esfahani

    2015-01-01

     Introduction: Human growth hormone (hGH) is a single-chain polypeptide derived from pituitary gland that participates in a wide range of biological functions and has therapeutic applications. The hormone consists of 191 amino acid residues (22kD) which folds into a four-helix bundle structure with two disulfide bridges. Due to the complication of internal cell protein extraction, several methods have been established for this purpose that most of them need special...

  7. The Effect of Thawing Condition for Frozen Fish Meats

    Science.gov (United States)

    Abe, Shuji; Osako, Kazufumi; Watanabe, Manabu; Suzuki, Toru

    The influence of thawing speed on denaturation of muscle protein and quality of several kinds frozen fish meat was studied by measuring Ca-ATPase activity, drip loss, and microscopic observation. Frozen bigeye tuna, chub mackerel, alaska pollack and yellow tail meat thawed at 10°C by air (slow thawing) and water (rapid thawing). Ca-ATPase activity of slow thawed fishes meat decreased than it of rapid thawed fishes meat. On the other hand drip loss of slow thawed fishes meat increased than it of rapid thawed fishes meat. Decreasing of Ca-ATPase activity showed a good linear relation to increasing of drip loss. Further, from microscopic observation, it was confirmed that muscle cells of slow thawed fishes meat were disrupted than it of rapid thawed samples. Therefore,it was suggested that rapid warming on thawing process is better to inhibit protein denaturation and drip loss.

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

    Science.gov (United States)

    2013-02-18

    REPORT Multi-Scale Process of soil Freezing, Thawing, and Thaw-Settlement 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: Freezing and thawing of soils...penetration resistance of sand after dynamic compaction, Second International Symposium on Computational Geomechanics (ComGeo II), Cavtat-Dubrovnik...2011) TOTAL: 4 Books Number of Manuscripts: Received Paper TOTAL: Patents Submitted Patents Awarded Awards MTS Visiting Professor of Geomechanics

  9. 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...

  10. SHORT-TERM FREE-FALL LANDING CAUSES REDUCED BONE SIZE AND BENDING ENERGY IN FEMORA OF GROWING RATS

    Directory of Open Access Journals (Sweden)

    Hsin-Shih Lin

    2013-03-01

    Full Text Available The purpose of this study was to determine the effects of a mechanical loading course (short-term free-fall landing on femoral geometry and biomechanical properties in growing rats. Thirty-two female Wistar rats (7-week-old were randomly assigned to three groups: L30 (n = 11, L10 (n = 11 and CON (n = 10 groups. Animals in the L10 and L30 groups were subjected to a 5-day free-fall landing program in which animals were dropped from a height of 40cm 10 and 30 times per day, respectively. Landing ground reaction force (GRF was measured on the 1st and 5th days of landing training. All animals were subjected to two fluorescent labeling injections on the days before and after the 5-day landing training. Three days after the last labeling injection, animals were sacrificed under deep anesthesia. Methods of dynamic histomorphometry, tissue geometry and tissue biomechanical measurements were used to investigate the response in femora. A significant decrease in peak GRF in the hind-limb was shown from day 1 to day 5. No significant difference was shown among groups in dynamic histomorphometry. Biomechanical property analyses showed significantly lower maximal energy and post-yield energy in the L10 and L30 groups as compared to the CON group (p < 0.05. Moreover, geometric measurements revealed that cross-sectional cortical areas and thicknesses were significantly lower in landing groups than in the CON group. Short-term (5-day free-fall landing training resulted in minor compromised long bone tissue, as shown by reduced bending energy and cortical bone area but not in other mechanical properties or tissue measurements (e.g. weights and length of growing female rats. Further studies would be valuable to investigate whether this compromised bone material represents the existence of a latency period in the adaptation of bone material to external mechanical loading.

  11. 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

  12. Isotropic thaw subsidence in undisturbed permafrost landscapes

    Science.gov (United States)

    Shiklomanov, Nikolay I.; Streletskiy, Dmitry A.; Little, Jonathon D.; Nelson, Frederick E.

    2013-12-01

    in undisturbed terrain within some regions of the Arctic reveal limited correlation between increasing air temperature and the thickness of the seasonally thawed layer above ice-rich permafrost. Here we describe landscape-scale, thaw-induced subsidence lacking the topographic contrasts associated with thermokarst terrain. A high-resolution, 11 year record of temperature and vertical movement at the ground surface from contrasting physiographic regions of northern Alaska, obtained with differential global positioning systems technology, indicates that thaw of an ice-rich layer at the top of permafrost has produced decimeter-scale subsidence extending over the entire landscapes. Without specialized observation techniques the subsidence is not apparent to observers at the surface. This "isotropic thaw subsidence" explains the apparent stability of active layer thickness records from some landscapes of northern Alaska, despite warming near-surface air temperatures. Integrated over extensive regions, it may be responsible for thawing large volumes of carbon-rich substrate and could have negative impacts on infrastructure.

  13. 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.

  14. Freeze-thaw performance testing of whole concrete railroad ties.

    Science.gov (United States)

    2013-10-01

    Freezing and thawing durability tests of prestressed concrete ties are normally performed according to ASTM C666 specifications. Small specimens are cut from the shoulders of concrete ties and tested through 300 cycles of freezing and thawing. Saw-cu...

  15. 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...

  16. Differentiation between fresh and frozen-thawed sea bass (Dicentrarchus labrax) fillets using two-dimensional gel electrophoresis.

    Science.gov (United States)

    Ethuin, Pierrette; Marlard, Sylvain; Delosière, Mylène; Carapito, Christine; Delalande, François; Van Dorsselaer, Alain; Dehaut, Alexandre; Lencel, Valérie; Duflos, Guillaume; Grard, Thierry

    2015-06-01

    This study aimed to identify a protein marker that can differentiate between fresh skinless and frozen-thawed sea bass (Dicentrarchus labrax) fillets using the two-dimensional polyacrylamide gel electrophoresis (2-DE) technique. Distinct gel patterns, due to proteins with low molecular weight and low isoelectric points, distinguished fresh fillets from frozen-thawed ones. Frozen-thawed fillets showed two specific protein spots as early as the first day of the study. However, these spots were not observed in fresh fillets until at least 13days of storage between 0 and 4°C, fillets were judged, beyond this period, fish were unfit for human consumption as revealed by complementary studies on fish spoilage indicators namely total volatile basic nitrogen and biogenic amines. Mass spectrometry identified the specific proteins as parvalbumin isoforms. Parvalbumins may thus be useful markers of differentiation between fresh and frozen-thawed sea bass fillets. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. L-carnitine Supplemented Extender Improves Cryopreserved-thawed Cat Epididymal Sperm Motility

    Directory of Open Access Journals (Sweden)

    S. Manee-in

    2014-06-01

    Full Text Available Cryopreservation of epididymal sperm is an effective technique to preserve genetic materials of domestic cats and wild felids when they unexpectedly die. However, this technique inevitably causes detrimental changes of cryopreserved-thawed spermatozoa, for example, by physical damage and excessive oxidative stress. L-carnitine is an antioxidant that has been used to improve sperm motility in humans and domestic animals. This study aimed to investigate the effects of L-carnitine on cat epididymal sperm quality following cryopreservation and thawing. After routine castration, cauda epididymides were collected from 60 cat testes. The epididymal spermatozoa from 3 cauda epididymides were pooled as 1 replicate. Spermatozoa samples (16 replicates were examined for spermatozoa quality and then randomly divided into 4 groups: 0 mM L-carnitine (control, 12.5 mM, 25 mM and 50 mM L-carnitine. The sperm aliquots were then equilibrated and conventionally frozen. After thawing, sperm motility, plasma membrane integrity, DNA integrity and acrosome integrity were evaluated. The 25 mM L-carnitine significantly improved sperm motility compared with a control group (p<0.05, although this was not significantly different among other concentrations. In conclusion, supplementation of 25 mM L-carnitine in freezing extender improves cauda epididymal spermatozoa motility. The effects of L-carnitine on the levels of oxidative stress during freezing and thawing remains to be examined.

  18. 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.

  19. Artificial insemination with frozen-thawed boar sperm.

    Science.gov (United States)

    Yeste, Marc; Rodríguez-Gil, Joan E; Bonet, Sergi

    2017-09-01

    Artificial insemination with frozen-thawed semen in pigs is not a routine technique; its use is restricted to specific cases, such as preservation of valuable genetic material (germplasm banks), safety strategies in case of natural disasters, long-distance transport of sperm, and in combination with sex-sorting. Cryoinjuries resulting from freeze-thawing protocols are a major concern with regard to the fertilization capacity of the treated sperm, which is lower than that of liquid-stored semen. Here, we provide an overview of artificial insemination using cryopreserved sperm, and summarize the factors that influence cryopreservation success before, during, and after freeze-thaw (i.e., sperm selection before starting the cryopreservation process, holding time, use of cryoprotectants, and rates of freezing and thawing) and that are driving the identification of biomarkers to predict sensitivity to cryodamage. Three different artificial insemination techniques (conventional or intracervical; intrauterine; and deep intrauterine) are also discussed with regards to their relevance when using frozen-thawed semen. Finally, we review the use of additives to freezing and thawing media, given reports that they may maintain and improve the quality and fertilizing capacity of frozen-thawed sperm. In sum, artificial insemination with frozen-thawed boar sperm can provide reasonable fertility outcomes, if freezable ejaculates, specific additives, and appropriate insemination techniques are used. © 2017 Wiley Periodicals, Inc.

  20. L-carnitine Supplemented Extender Improves Cryopreserved-thawed Cat Epididymal Sperm Motility

    OpenAIRE

    S. Manee-in; S. Parmornsupornvichit; S. Kraiprayoon; T. Tharasanit; P. Chanapiwat; K. Kaeoket

    2014-01-01

    Cryopreservation of epididymal sperm is an effective technique to preserve genetic materials of domestic cats and wild felids when they unexpectedly die. However, this technique inevitably causes detrimental changes of cryopreserved-thawed spermatozoa, for example, by physical damage and excessive oxidative stress. L-carnitine is an antioxidant that has been used to improve sperm motility in humans and domestic animals. This study aimed to investigate the effects of L-carnitine on cat epididy...

  1. Transplantation of frozen-thawed ovarian tissue

    DEFF Research Database (Denmark)

    Gellert, S E; Pors, S E; Kristensen, Stine Gry

    2018-01-01

    . CONCLUSION: This study found no indications of sufficient numbers of malignant cells present in the ovarian tissue to cause recurrence of cancer after OTT. Further, it is unlikely that OTC affects the well-being of children born. OTC is now an established method of fertility preservation in Denmark......PURPOSE: The purpose of the study is to review all peer-reviewed published reports of women receiving ovarian tissue transplantation (OTT) with frozen/thawed tissue (OTC) with respect to age, diagnosis, transplantation site, fertility outcome, and potential side effects, including data from all...... women in the Danish program. METHODS: A systematic review of the literature was performed in PubMed combined with results from all patients who had received OTT in Denmark up to December 2017. RESULTS: OTT has been reported from 21 different countries comprising a total of 360 OTT procedures in 318...

  2. Freeze-thaw durability of air-entrained concrete.

    Science.gov (United States)

    Shang, Huai-Shuai; Yi, Ting-Hua

    2013-01-01

    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.

  3. 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.

  4. Differentiation between fresh beef and thawed frozen beef.

    Science.gov (United States)

    Chen, M T; Yang, W D; Guo, S L

    1988-01-01

    In order to prevent meat retailers offering thawed, imported frozen beef as fresh domestic beef, the method of Gottesmann and Hamm for differentiating between fresh and frozen/thawed meat is recommended. The principle of this method is based on the fact that freezing and thawing of meat results in a release of the enzyme β-hydroxyacyl CoA-dehydrogenase (HADH) from the mitochondrion into the sarcoplasm; an elevated HADH activity in the muscle press-juice indicates freezing and thawing of tissue. The HADH colour test of Gottesmann and Hamm was modified by replacing the electron-transmitter meldolablue by resazurin which results in a much higher colour stability after reaction with fresh meat extracts. Copyright © 1989. Published by Elsevier Ltd.

  5. The Thaw:How Mexico and The United States Thawed Their Cold Peace And What Comes Next

    Science.gov (United States)

    2014-04-01

    Trade Agreement ( NAFTA ) in 1994. On the political front, Mexico and the United States have made little progress toward deepening and thickening the...AU/ACSC/GRISWOLD/AY14 AIR COMMAND AND STAFF COLLEGE AIR UNIVERSITY THE THAW: HOW MEXICO & THE UNITED STATES THAWED THEIR COLD PEACE AND WHAT...Fortunately, at a decisive moment, the United States nudged Mexico toward integration with the liberal international economic order. Mexico has

  6. 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.

  7. 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.

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

    Directory of Open Access Journals (Sweden)

    Jurandy Mauro Penitente-Filho

    2014-01-01

    Full Text Available 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.

  9. 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....

  10. Repeated freeze-thaw cycles reduce the survival rate of osteocytes in bone-tendon constructs without affecting the mechanical properties of tendons.

    Science.gov (United States)

    Suto, Kaori; Urabe, Ken; Naruse, Kouji; Uchida, Kentaro; Matsuura, Terumasa; Mikuni-Takagaki, Yuko; Suto, Mitsutoshi; Nemoto, Noriko; Kamiya, Kentaro; Itoman, Moritoshi

    2012-03-01

    Frozen bone-patellar tendon bone allografts are useful in anterior cruciate ligament reconstruction as the freezing procedure kills tissue cells, thereby reducing immunogenicity of the grafts. However, a small portion of cells in human femoral heads treated by standard bone-bank freezing procedures survive, thus limiting the effectiveness of allografts. Here, we characterized the survival rates and mechanisms of cells isolated from rat bones and tendons that were subjected to freeze-thaw treatments, and evaluated the influence of these treatments on the mechanical properties of tendons. After a single freeze-thaw cycle, most cells isolated from frozen bone appeared morphologically as osteocytes and expressed both osteoblast- and osteocyte-related genes. Transmission electron microscopic observation of frozen cells using freeze-substitution revealed that a small number of osteocytes maintained large nuclei with intact double membranes, indicating that these osteocytes in bone matrix were resistant to ice crystal formation. We found that tendon cells were completely killed by a single freeze-thaw cycle, whereas bone cells exhibited a relatively high survival rate, although survival was significantly reduced after three freeze-thaw cycles. In patella tendons, the ultimate stress, Young's modulus, and strain at failure showed no significant differences between untreated tendons and those subjected to five freeze-thaw cycles. In conclusion, we identified that cells surviving after freeze-thaw treatment of rat bones were predominantly osteocytes. We propose that repeated freeze-thaw cycles could be applied for processing bone-tendon constructs prior to grafting as the treatment did not affect the mechanical property of tendons and drastically reduced surviving osteocytes, thereby potentially decreasing allograft immunogenecity.

  11. Spring thaw predictor & development of real time spring load restrictions.

    Science.gov (United States)

    2011-02-01

    This report summarizes the results of a study to develop a correlation between weather forecasts and the : spring thaw in order to reduce the duration of load limits on New Hampshire roadways. The study used a falling : weight deflectometer at 10 sit...

  12. Freeze/thaw phenomena in concrete at low temperatures

    DEFF Research Database (Denmark)

    Johannesson, Björn

    2007-01-01

    , however, in most part unknown. In this work samples of concrete at different water to cement ratios and air bubble contents subjected to freeze/thaw cycles with the lowest temperature at about -80 oC are investigated. By adopting a novel technique a scanning calorimeter is used to obtain data from which...

  13. Hydrologic impacts of thawing permafrost—A review

    Science.gov (United States)

    Walvoord, Michelle Ann; Kurylyk, Barret L.

    2016-01-01

    Where present, permafrost exerts a primary control on water fluxes, flowpaths, and distribution. Climate warming and related drivers of soil thermal change are expected to modify the distribution of permafrost, leading to changing hydrologic conditions, including alterations in soil moisture, connectivity of inland waters, streamflow seasonality, and the partitioning of water stored above and below ground. The field of permafrost hydrology is undergoing rapid advancement with respect to multiscale observations, subsurface characterization, modeling, and integration with other disciplines. However, gaining predictive capability of the many interrelated consequences of climate change is a persistent challenge due to several factors. Observations of hydrologic change have been causally linked to permafrost thaw, but applications of process-based models needed to support and enhance the transferability of empirical linkages have often been restricted to generalized representations. Limitations stem from inadequate baseline permafrost and unfrozen hydrogeologic characterization, lack of historical data, and simplifications in structure and process representation needed to counter the high computational demands of cryohydrogeologic simulations. Further, due in part to the large degree of subsurface heterogeneity of permafrost landscapes and the nonuniformity in thaw patterns and rates, associations between various modes of permafrost thaw and hydrologic change are not readily scalable; even trajectories of change can differ. This review highlights promising advances in characterization and modeling of permafrost regions and presents ongoing research challenges toward projecting hydrologic and ecologic consequences of permafrost thaw at time and spatial scales that are useful to managers and researchers.

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

    Indian Academy of Sciences (India)

    Unknown

    2000-06-03

    Jun 3, 2000 ... Abstract. 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 lar- ger median radius of the pores and total porosity of M–SAB compared to those of M–PC ...

  15. Cryopreservation of Byrsonima intermedia embryos followed by room temperature thawing

    Directory of Open Access Journals (Sweden)

    Luciano Coutinho Silva

    2014-07-01

    Full Text Available Byrsonima intermedia is a shrub from the Brazilian Cerrado with medicinal properties. The storage of biological material at ultra-low temperatures (-196°C is termed cryopreservation and represents a promising technique for preserving plant diversity. Thawing is a crucial step that follows cryopreservation. The aim of this work was to cryopreserve B. intermedia zygotic embryos and subsequently thaw them at room temperature in a solution rich in sucrose. The embryos were decontaminated and desiccated in a laminar airflow hood for 0-4 hours prior to plunging into liquid nitrogen. The embryo moisture content (% MC during dehydration was assessed. Cryopreserved embryos were thawed in a solution rich in sucrose at room temperature, inoculated in a germination medium and maintained in a growth chamber. After 30 days, the embryo germination was evaluated. No significant differences were observed between the different embryo dehydration times, where they were dehydrated for at least one hour. Embryos with a MC between 34.3 and 20.3% were germinated after cryopreservation. In the absence of dehydration, all embryos died following cryopreservation. We conclude that B. intermedia zygotic embryos can be successfully cryopreserved and thawed at room temperature after at least one hour of dehydration in a laminar airflow bench.

  16. 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...

  17. Microbial Insights into Shifting Methane Production Potential in Thawing Permafrost

    Science.gov (United States)

    Crossen, K.; Wilson, R.; Raab, N.; Neumann, R.; Chanton, J.; Saleska, S. R.; Rich, V. I.

    2017-12-01

    Permafrost, which stores 50% of global soil carbon, is thawing rapidly due to climate change, and resident microbes are contributing to changing carbon gas emissions. Predictions of the fate of carbon in these regions is poorly constrained; however, improved, careful mapping of microbial community members influencing CO2 and CH4 emissions will help clarify the system response to continued change. In order to more fully understand connections between the microbial communities, major geochemical transformations, and CO2 and CH4 emissions, peat cores were collected from the active layers of three permafrost habitats spanning a thaw gradient (collapsed palsa, bog, and fen) at Stordalen Mire, Abisko, Sweden. Anaerobic incubations of shallow and deep subsamples from these sites were performed, with time-course characterization of the changes in microbial communities, peat geochemistry, and carbon gas production. The latter were profiled with 16S rRNA amplicon sequencing, and targeted metagenomes. The communities within each habitat and depth were statistically distinct, and changed significantly over the course of the incubations. Acidobacteria was consistently the dominant bacterial phylum in all three habitat types. With increased thaw, the relative abundance of Actinobacteria tended to decrease, while Chloroflexi and Bacteroidetes increased with thaw. The relative abundance of methanogens increased with thaw and with depth within each habitat. Over time in the incubations, the richness of the communities tended to decrease. Homoacetogenesis (CO2 + H2 -> CH3COOH) has been documented in other peatlands, and homoacetogens can influence CH4 production by interacting with methanogens, competing with hydrogenotrophs while providing substrate for acetoclasts. Modelling of microbial reaction networks suggests potential for highest homoacetogenesis rates in the collapsed palsa, which also contains the highest relative abundances of lineages taxonomically affiliated with known

  18. Supplementing zinc oxide nanoparticles to cryopreservation medium minimizes the freeze-thaw-induced damage to spermatozoa.

    Science.gov (United States)

    Isaac, Ann V; Kumari, Sandhya; Nair, Ramya; Urs, Deepak Raj; Salian, Sujith Raj; Kalthur, Guruprasad; Adiga, Satish Kumar; Manikkath, Jyothsna; Mutalik, Srinivas; Sachdev, Divya; Pasricha, Renu

    2017-12-16

    The sperm DNA integrity post cryopreservation of human semen samples is one of the serious concerns in human infertility treatment. In the present study, the beneficial effects of zinc oxide nanoparticles in preserving the functional ability of spermatozoa was explored. Ejaculates of normozoospermic men cryopreserved along with Zinc oxide nanoparticles (ZnONPs) exhibited non-significantly higher percentage of total and progressive motility in frozen-thawed samples compared to control. The sperm chromatin damage and malondialdehyde (MDA) level was significantly lower in ZnONPs group (P spermatozoa's ability to undergo acrosome reaction was also unaltered. Fluorescence microscopy and High resolution transmission electron microscopy analysis demonstrated that the ZnONPs do not penetrate the membrane of spermatozoa but stay around the spermatozoa. In conclusion, the presence of ZnONPs during cryopreservation appears to be beneficial to the spermatozoa as they withstand freeze-thaw process competently better than control, without any adverse effect shown. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Small molecule ice recrystallization inhibitors mitigate red blood cell lysis during freezing, transient warming and thawing.

    Science.gov (United States)

    Briard, Jennie G; Poisson, Jessica S; Turner, Tracey R; Capicciotti, Chantelle J; Acker, Jason P; Ben, Robert N

    2016-03-29

    During cryopreservation, ice recrystallization is a major cause of cellular damage. Conventional cryoprotectants such as dimethyl sulfoxide (DMSO) and glycerol function by a number of different mechanisms but do not mitigate or control ice recrystallization at concentrations utilized in cryopreservation procedures. In North America, cryopreservation of human red blood cells (RBCs) utilizes high concentrations of glycerol. RBC units frozen under these conditions must be subjected to a time-consuming deglycerolization process after thawing in order to remove the glycerol to recrystallization inhibitors (IRIs) that are effective cryoprotectants for human RBCs, resulting in 70-80% intact RBCs using only 15% glycerol and slow freezing rates. These compounds are capable of reducing the average ice crystal size of extracellular ice relative to a 15% glycerol control validating the positive correlation between a reduction in ice crystal size and increased post-thaw recovery of RBCs. The most potent IRI from this study is also capable of protecting frozen RBCs against the large temperature fluctuations associated with transient warming.

  20. 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

  1. 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.

  2. Nonlinear CO2 flux response to 7 years of experimentally induced permafrost thaw.

    Science.gov (United States)

    Mauritz, Marguerite; Bracho, Rosvel; Celis, Gerardo; Hutchings, Jack; Natali, Susan M; Pegoraro, Elaine; Salmon, Verity G; Schädel, Christina; Webb, Elizabeth E; Schuur, Edward A G

    2017-09-01

    Rapid Arctic warming is expected to increase global greenhouse gas concentrations as permafrost thaw exposes immense stores of frozen carbon (C) to microbial decomposition. Permafrost thaw also stimulates plant growth, which could offset C loss. Using data from 7 years of experimental Air and Soil warming in moist acidic tundra, we show that Soil warming had a much stronger effect on CO 2 flux than Air warming. Soil warming caused rapid permafrost thaw and increased ecosystem respiration (R eco ), gross primary productivity (GPP), and net summer CO 2 storage (NEE). Over 7 years R eco , GPP, and NEE also increased in Control (i.e., ambient plots), but this change could be explained by slow thaw in Control areas. In the initial stages of thaw, R eco , GPP, and NEE increased linearly with thaw across all treatments, despite different rates of thaw. As thaw in Soil warming continued to increase linearly, ground surface subsidence created saturated microsites and suppressed R eco , GPP, and NEE. However R eco and GPP remained high in areas with large Eriophorum vaginatum biomass. In general NEE increased with thaw, but was more strongly correlated with plant biomass than thaw, indicating that higher R eco in deeply thawed areas during summer months was balanced by GPP. Summer CO 2 flux across treatments fit a single quadratic relationship that captured the functional response of CO 2 flux to thaw, water table depth, and plant biomass. These results demonstrate the importance of indirect thaw effects on CO 2 flux: plant growth and water table dynamics. Nonsummer R eco models estimated that the area was an annual CO 2 source during all years of observation. Nonsummer CO 2 loss in warmer, more deeply thawed soils exceeded the increases in summer GPP, and thawed tundra was a net annual CO 2 source. © 2017 John Wiley & Sons Ltd.

  3. 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

  4. Comparison of the mechanical behaviors of semicontoured, locking plate-rod fixation and anatomically contoured, conventional plate-rod fixation applied to experimentally induced gap fractures in canine femora.

    Science.gov (United States)

    Goh, Clara S S; Santoni, Brandon G; Puttlitz, Christian M; Palmer, Ross H

    2009-01-01

    To compare the mechanical behaviors of a semicontoured, locking compression plate-rod (LCP-rod) construct and an anatomically contoured, limited-contact dynamic compression plate-rod (LC-DCP-rod) construct applied to experimentally induced gap fractures in canine femora. 16 femora from 8 cadaveric dogs. 8 limbs from 8 dogs were assigned to the LCP-rod construct group or the LC-DCP-rod construct group. In each femur, a 39-mm mid-diaphyseal ostectomy was performed at the same plate location and the assigned construct was applied. Construct stiffness and ostectomy gap subsidence were determined before and after cyclic axial loading (6,000 cycles at 20%, 40%, and 60% of live body weight [total, 18,000 cycles]). Three constructs from each group further underwent 45,000 cycles at 60% of body weight (total, 63,000 cycles). Following cyclic loading, mode of failure during loading to failure at 5 mm/min was recorded for all constructs. After 18,000 or 63,000 cycles, construct stiffness did not differ significantly between construct groups. No implant failure occurred in any construct that underwent 63,000 cycles. In both construct groups, ostectomy gap subsidence similarly increased as axial load increased but did not change after 18,000 cycles. Mean +/- SEM loads at failure in the LCP-rod (1,493.83 +/- 200.12 N) and LC-DCP-rod (1,276.05 +/- 156.11 N) construct groups were not significantly different. The primary failure event in all constructs occurred at the screw hole immediately distal to the ostectomy. Biomechanically, the semicontoured LCP-rod construct is similar to the anatomically contoured LC-DCP-rod system.

  5. Use of frozen-thawed semen in equine artificial insemination programmes

    Directory of Open Access Journals (Sweden)

    Alonso A

    2016-12-01

    Full Text Available The use of equine frozen semen has variable results. Pregnancy rates per cycle may be between 10 to 70%. Although an inseminating dose of 280 a 320 millones progressive motile sperm (PMS has been recommended, under experimental conditions it is posible to obtain acceptable results with doses of 50 to 100 millones PMS. Deep intrauterine insemination is prefered when using frozen thawed semen, which consists in depositing the dose at the tip of the horn, ipsiltateral to ovulation. Young mares usually have better uterine condition and that increase their chance of become pregnant. It is important to make a correct follicular monitoring, in order to determine the right time to induce ovulation. Ovulation may be induced with Human Chorionic Gonadotrophin (hCG or deslorelin. It posible to perform a fixed time insemination or to choose an ultrasound follicular following protocol, inseminating within 6 h of ovulation. This option offers the best prenancy rates. Our laboratory manages a protocol which includes ultrasound monitoring every 6 hours, beginning 24 hous after induction of ovulation; this protocol had a first insemination pregnancy rate of 73%. If we consider that one of the main disadvantages of frozen-thawed semen is decreased fertility, these results are encouraging, since they are similar to those obtained with fresh or cooled semen, so it may represent an advantage when having stored semen of stallions that are dead, or have been sold or even castrated.

  6. Freezing and thawing resistance of aerial lime mortar with metakaolin\

    Czech Academy of Sciences Publication Activity Database

    Nunes, Cristiana Lara; Slížková, Zuzana

    2016-01-01

    Roč. 114, July (2016), s. 896-905 ISSN 0950-0618 R&D Projects: GA ČR(CZ) GBP105/12/G059 Institutional support: RVO:68378297 Keywords : freeze-thaw * lime * metakaolin * linseed oil * mortar * water-repellency Subject RIV: JN - Civil Engineering Impact factor: 3.169, year: 2016 http://www.sciencedirect.com/science/article/pii/S0950061816305645

  7. Exploring Viral Mediated Carbon Cycling in Thawing Permafrost Microbial Communities

    Science.gov (United States)

    Trubl, G. G.; Solonenko, N.; Moreno, M.; Sullivan, M. B.; Rich, V. I.

    2014-12-01

    Viruses are the most abundant biological entities on Earth and their impact on carbon cycling in permafrost habitats is poorly understood. Arctic C cycling is particularly important to interpret due to the rapid climate change occurring and the large amount of C stockpiled there (~1/3 of global soil C is stored in permafrost). Viruses of microbes (i.e. phages) play central roles in C cycling in the oceans, through cellular lysis (phage drive the largest ocean C flux about 150 Gt yr-1, dwarfing all others by >5-fold), production of associated DOC, as well as transport and expression during infection (1029 transduction events day-1). C cycling in thawing permafrost systems is critical in understanding the climate trajectory and phages may be as important for C cycling here as they are in the ocean. The thawed C may become a food source for microbes, producing CO2 and potentially CH4, both potent greenhouse gases. To address the potential role of phage in C cycling in these dynamic systems, we are examining phage from an arctic permafrost thaw gradient in northern Sweden. We have developed a protocol for successfully extracting phage from peat soils and are quantifying phage in 15 peat and 2 lake sediment cores, with the goal of sequencing viromes. Preliminary data suggest that phage are present at 109 g-1 across the permafrost thaw gradient (compared to the typical marine count ~105 ml-1), implying a potentially robust phage-host interaction web in these changing environments. We are examining phage from 11 depth intervals (covering the active and permafrost layer) in the cores to assess phage-host community dynamics. Phage morphology and abundance for each layer and environment are being determined using qTEM and EFM. Understanding the phage that infect bacteria and archaea in these rapidly changing habitats will provide insight into the controls on current and future CH4 and CO2 emissions in permafrost habitats.

  8. Dissolved organic matter photolysis in Canadian arctic thaw ponds

    Science.gov (United States)

    Laurion, Isabelle; Mladenov, Natalie

    2013-09-01

    The abundant thaw lakes and ponds in the circumarctic receive a new pool of organic carbon as permafrost peat soils degrade, which can be exposed to significant irradiance that potentially increases as climate warms and ice cover shortens. Exposure to sunlight is known to accelerate the transformation of dissolved organic matter (DOM) into molecules that can be more readily used by microbes. We sampled the water from two common classes of ponds found in the ice-wedge system of continuous permafrost regions of Canada, polygonal and runnel ponds, and followed the transformation of DOM over 12 days by looking at dissolved organic carbon (DOC) concentration and DOM absorption and fluorescence properties. The results indicate a relatively fast decay of color (3.4 and 1.6% loss d-1 of absorption at 320 nm for the polygonal and runnel pond, respectively) and fluorescence (6.1 and 8.3% loss d-1 of total fluorescent components, respectively) at the pond surface, faster in the case of humic-like components, but insignificant losses of DOC over the observed period. This result indicates that direct DOM mineralization (photochemical production of CO2) is apparently minor in thaw ponds compared to the photochemical transformation of DOM into less chromophoric and likely more labile molecules with a greater potential for microbial mineralization. Therefore, DOM photolysis in arctic thaw ponds can be considered as a catalytic mechanism, accelerating the microbial turnover of mobilized organic matter from thawing permafrost and the production of greenhouse gases, especially in the most shallow ponds. Under a warming climate, this mechanism will intensify as summers lengthen.

  9. Dissolved organic matter photolysis in Canadian arctic thaw ponds

    International Nuclear Information System (INIS)

    Laurion, Isabelle; Mladenov, Natalie

    2013-01-01

    The abundant thaw lakes and ponds in the circumarctic receive a new pool of organic carbon as permafrost peat soils degrade, which can be exposed to significant irradiance that potentially increases as climate warms and ice cover shortens. Exposure to sunlight is known to accelerate the transformation of dissolved organic matter (DOM) into molecules that can be more readily used by microbes. We sampled the water from two common classes of ponds found in the ice-wedge system of continuous permafrost regions of Canada, polygonal and runnel ponds, and followed the transformation of DOM over 12 days by looking at dissolved organic carbon (DOC) concentration and DOM absorption and fluorescence properties. The results indicate a relatively fast decay of color (3.4 and 1.6% loss d −1 of absorption at 320 nm for the polygonal and runnel pond, respectively) and fluorescence (6.1 and 8.3% loss d −1 of total fluorescent components, respectively) at the pond surface, faster in the case of humic-like components, but insignificant losses of DOC over the observed period. This result indicates that direct DOM mineralization (photochemical production of CO 2 ) is apparently minor in thaw ponds compared to the photochemical transformation of DOM into less chromophoric and likely more labile molecules with a greater potential for microbial mineralization. Therefore, DOM photolysis in arctic thaw ponds can be considered as a catalytic mechanism, accelerating the microbial turnover of mobilized organic matter from thawing permafrost and the production of greenhouse gases, especially in the most shallow ponds. Under a warming climate, this mechanism will intensify as summers lengthen. (letter)

  10. 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.

  11. 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.

  12. Field information links permafrost carbon to physical vulnerabilities of thawing

    Science.gov (United States)

    Harden, Jennifer W.; Koven, Charles; Ping, Chien-Lu; Hugelius, Gustaf; McGuire, A. David; Camill, P.; Jorgenson, Torre; Kuhry, Peter; Michaelson, Gary; O'Donnell, Jonathan A.; Schuur, Edward A.G.; Tamocai, Charles; Johnson, K.; Grosse, G.

    2012-01-01

    Deep soil profiles containing permafrost (Gelisols) were characterized for organic carbon (C) and total nitrogen (N) stocks to 3m depths. Using the Community Climate System Model (CCSM4) we calculate cumulative probability functions (PDFs) for active layer depths under current and future climates. The difference in PDFs over time was multiplied by C and N contents of soil horizons in Gelisol suborders to calculate newly thawed C and N, Thawing ranged from 147 PgC with 10 PgN by 2050 (representative concentration pathway RCP scenario 4.5) to 436 PgC with 29 PgN by 2100 (RCP 8.5). Organic horizons that thaw are vulnerable to combustion, and all horizon types are vulnerable to shifts in hydrology and decomposition. The rates and extent of such losses are unknown and can be further constrained by linking field and modelling approaches. These changes have the potential for strong additional loading to our atmosphere, water resources, and ecosystems.

  13. 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.

  14. 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.

  15. Phototrophic pigment diversity and picophytoplankton in permafrost thaw lakes

    Science.gov (United States)

    Przytulska, A.; Comte, J.; Crevecoeur, S.; Lovejoy, C.; Laurion, I.; Vincent, W. F.

    2016-01-01

    Permafrost thaw lakes (thermokarst lakes) are widely distributed across the northern landscape, and are known to be biogeochemically active sites that emit large amounts of carbon to the atmosphere as CH4 and CO2. However, the abundance and composition of the photosynthetic communities that fix CO2 have been little explored in this ecosystem type. In order to identify the major groups of phototrophic organisms and their controlling variables, we sampled 12 permafrost thaw lakes along a permafrost degradation gradient in northern Québec, Canada. Additional samples were taken from five rock-basin reference lakes in the region to determine if the thaw lakes differed in limnological properties and phototrophs. Phytoplankton community structure was determined by high-performance liquid chromatography analysis of their photoprotective and photosynthetic pigments, and autotrophic picoplankton concentrations were assessed by flow cytometry. One of the black-colored lakes located in a landscape of rapidly degrading palsas (permafrost mounds) was selected for high-throughput 18S rRNA sequencing to complement conclusions based on the pigment and cytometry analyses. The results showed that the limnological properties of the thaw lakes differed significantly from the reference lakes, and were more highly stratified. However, both waterbody types contained similarly diverse phytoplankton groups, with dominance of the pigment assemblages by fucoxanthin-containing taxa, as well as chlorophytes, cryptophytes and cyanobacteria. Chlorophyll a concentrations (Chl a) were correlated with total phosphorus (TP), and both were significantly higher in the thaw lakes (overall means of 3.3 µg Chl a L-1 and 34 µg TP L-1) relative to the reference lakes (2.0 µg Chl a L-1 and 8.2 µg TP L-1). Stepwise multiple regression of Chl a against the other algal pigments showed that it was largely a function of alloxanthin, fucoxanthin and Chl b (R2 = 0.85). The bottom waters of two of the thaw

  16. 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

  17. 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.

  18. Research on strength attenuation law of concrete in freezing - thawing environment

    Science.gov (United States)

    Xiao, qianhui; Cao, zhiyuan; Li, qiang

    2018-03-01

    By rapid freezing and thawing method, the experiments of concrete have been 300 freeze-thaw cycles specimens in the water. The cubic compression strength value under different freeze-thaw cycles was measured. By analyzing the test results, the water-binder ratio of the concrete under freeze-thaw environments, fly ash and air entraining agent is selected dosage recommendations. The exponential attenuation prediction model and life prediction model of compression strength of concrete under freezing-thawing cycles considering the factors of water-binder ratio, fly ash content and air-entraining agent dosage were established. The model provides the basis for predicting the durability life of concrete under freezing-thawing environment. It also provides experimental basis and references for further research on concrete structures with antifreeze requirements.

  19. Initial discussion on the damage propagation of rock under the frost and thaw condition

    Energy Technology Data Exchange (ETDEWEB)

    Yang, G.; Pu, Y. [Xian University of Science and Technology, Xian (China). Dept. of Civil Engineering

    2002-08-01

    Based on the experimental results obtained from CT scanning of rocks under the condition of frost-and-thaw cycle, the characteristics of damage propagation of three types of rock materials (sandstone, shale and coal) were studied under the conditions of frost-and-thaw cycles. The effect of the number of frost-and-thaw cycles on the damage propagation of rock is emphasised in the discussion. 6 refs., 4 figs., 4 tabs.

  20. 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

    Decomposition of organic carbon from thawing permafrost soils and the resulting release of carbon to the atmosphere are considered to represent a potentially critical global-scale feedback on climate change1, 2. The accompanying heat production from microbial metabolism of organic material has been...... 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...... by microbial heat production with crucial implications for the amounts of carbon being decomposed. The same is shown to be true for organic middens5 with the risk of losing unique evidence of early human presence in the Arctic....

  1. Effect of Novel Quick Freezing Techniques Combined with Different Thawing Processes on Beef Quality.

    Science.gov (United States)

    Jo, Yeon-Ji; Jang, Min-Young; Jung, You-Kyoung; Kim, Jae-Hyeong; Sim, Jun-Bo; Chun, Ji-Yeon; Yoo, Seon-Mi; Han, Gui-Jung; Min, Sang-Gi

    2014-01-01

    This study investigated the effect of various freezing and thawing techniques on the quality of beef. Meat samples were frozen using natural convection freezing (NF), individual quick freezing (IQF), or cryogenic freezing (CF) techniques, followed by natural convection thawing (NCT) or running water thawing (RT). The meat was frozen until the core temperature reached -12℃ and then stored at -24℃, followed by thawing until the temperature reached 5℃. Quality parameters, such as the pH, water binding properties, CIE color, shear force, and microstructure of the beef were elucidated. Although the freezing and thawing combinations did not cause remarkable changes in the quality parameters, rapid freezing, in the order of CF, IQF, and NF, was found to minimize the quality deterioration. In the case of thawing methods, NCT was better than RT and the meat quality was influence on the thawing temperature rather than the thawing rate. Although the microstructure of the frozen beef exhibited an excessive loss of integrity after the freezing and thawing, it did not cause any remarkable change in the beef quality. Taken together, these results demonstrate that CF and NCT form the best combination for beef processing; however, IQF and NCT may have practical applications in the frozen food industry.

  2. 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.

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

    Data.gov (United States)

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

  4. Post-thaw bovine spermatozoal quality estimated from fresh samples.

    Science.gov (United States)

    Thomas, C A; Garner, D L

    1994-01-01

    Comparisons were made among flow cytometrically quantified populations of fresh and cryopreserved bovine spermatozoa, tri-stained with fluorophores rhodamine 123 (R123), 5- (and 6-) carboxy-4',5'-dimethylfluorescein diacetate (CMFDA), and propidium iodide (PI), and analyzed by dual parameter flow cytometry. The purpose was to find parameters in fresh semen samples that were potentially predictive of frozen sample parameters so that bulls with marginal cryopreservation capacity could be identified. Fresh and cryopreserved aliquots of semen from two sets of six bulls were semen processed in either milk (bulls 1-6) or egg yolk citrate (bulls 11-16). Membrane-damaged red (PI) and intact green (CMFDA + R123) populations were evaluated as percentages of 10,000-cell samples or numbers per straw. In milk, gated central subsets of membrane-damaged sperm cells in fresh samples and moribund cells in post-thaw samples were significantly correlated for sample percentages (r = 0.90, P = 0.014) and cell numbers per straw (r = 0.94, P = 0.006). In egg yolk citrate, fresh and frozen membrane-damaged populations were correlated (percentages: r = 0.81, P = 0.048; numbers: r = 0.88, P = 0.019). Additionally, post-thaw motility estimated by a photographic method was correlated with the number of sperm cells per straw in the intact central green subset (r = 0.98, P = 0.0006). These findings suggest that partitioning red and gree populations into smaller, central subset populations reveals significant relationships between fresh and cryopreserved bull ejaculates. The proportion of membrane-damaged spermatozoa in fresh semen seems to be predictive of the proportion of post-thaw membrane-damaged or moribund spermatozoa. The data consistently showed ejaculates of bulls 1 and 12 as having the greatest cryopreservation potentials, and bulls 4 and 16 the least. Thus, flow cytometric evaluation of fresh semen may be useful for identifying young sires with relatively poor fertilizing potential.

  5. 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.

  6. 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, M.; Billet, M. F.; Canário, J.; Cory, R. M.; Deshpande, B. N.; Helbig, M.; Jammet, M.; Karlsson, J.; Larouche, J.; MacMillan, G.; Rautio, M.; Anthony, K. M. Walter; Wickland, K. P.

    2015-12-01

    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

  7. 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

  8. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Melillo, Jerry [Marine Biological Lab., Woods Hole, MA (United States)

    2017-12-12

    uncertainties. Based on our study results along with a review of observed and projected climate changes in Northern Eurasia by others, we have also outlined a more integrated modelling approach that may be developed and applied in future studies to better capture the influence of earth system feedbacks and human activities on the evolution of climate change effects over time. Specifically, we have examined: 1) how evapotranspiration and water availability have been changing in Northern Eurasia and may change in the future including the impact of forcing uncertainties (Liu et al., 2013, 2014, 2015); 2) how soil consumption of atmospheric methane across the globe have been influenced and may be influenced by climate change and nitrogen deposition during the 20th and 21st centuries (Zhuang et al., 2013); 3) how wetland inundation extent influences net CO2 and CH4 fluxes from northern high latitudes (Zhuang et al., 2015); 4) the relative effects of various environmental factors (including permafrost degradation) on terrestrial dissolved organic carbon (DOC) loading of river networks across the pan-Arctic and how they have changed over the 20th century (Kicklighter et al., 2013); 5) the impacts of recent and future permafrost thaw on land-atmosphere greenhouse gas exchange across the pan-Arctic (Gao et al., 2012, 2013; Hayes et al., 2014; Kicklighter et al. 2015a, 2018); 6) how climate-induced vegetation shifts may affect carbon fluxes and future land use in Northern Eurasia (Jiang et al., 2012, 2016; Kicklighter et al., 2014a) and the globe (Zhuang et al. 2015b); 7) the relative importance of legacies from past land use, future land-use change and climate change on projections of terrestrial carbon fluxes (Monier et al., 2015; Kicklighter et al., 2016); and 8) how the effects of earth system feedbacks and human activities can be better incorporated in assessments of climate change impacts (Monier et al., 2017; Groisman et al., 2018).

  10. 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

  11. 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...

  12. Effects of straw mulching on soil evaporation during the soil thawing ...

    Indian Academy of Sciences (India)

    26

    The influence of different quantities of straw mulch on soil water evaporation during the thawing period was analyzed using the Mallat algorithm, statistical analysis and information cost function. The results showed that straw mulching could delay the thawing of the surface soil by 3-6 d, decrease the speed at which the ...

  13. Repeated freeze-thaw cycles induce embolism in drought stressed conifers (Norway spruce, stone pine).

    Science.gov (United States)

    Mayr, Stefan; Gruber, Andreas; Bauer, Helmut

    2003-07-01

    Freezing and thawing lead to xylem embolism when gas bubbles caused by ice formation expand during the thaw process. However, previous experimental studies indicated that conifers are resistant to freezing-induced embolism, unless xylem pressure becomes very negative during the freezing. In this study, we show that conifers experienced freezing-induced embolism when exposed to repeated freeze-thaw cycles and simultaneously to drought. Simulating conditions at the alpine timberline (128 days with freeze-thaw events and thawing rates of up to 9.5 K h(-1) in the xylem of exposed twigs during winter), young trees of Norway spruce [Picea abies (L.) Karst.] and stone pine (Pinus cembra L.) were exposed to 50 and 100 freeze-thaw cycles. This treatment caused a significant increase in embolism rates in drought-stressed samples. Upon 100 freeze-thaw cycles, vulnerability thresholds (50% loss of conductivity) were shifted 1.8 MPa (Norway spruce) and 0.8 MPa (stone pine) towards less negative water potentials. The results demonstrate that freeze-thaw cycles are a possible reason for winter-embolism in conifers observed in several field studies. Freezing-induced embolism may contribute to the altitudinal limits of conifers.

  14. 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

  15. 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...

  16. 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.

  17. 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.

  18. 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.

  19. INFLUENCE OF CYCLIC FREEZING AND THAWING UPON SPRUCE WOOD PROPERTIES

    Directory of Open Access Journals (Sweden)

    Maria Bernadett SZMUTKU

    2012-03-01

    Full Text Available The paper presents the results concerning the change of some physical and mechanical properties of spruce wood (Picea abies L., after repeated freezing and thawing, respectively after being subjected to temperature variation from positive valuea (+100C to negative values (-250C. Through this approach, the authors aimed at simulating normal temperature variations that occur in winter between night and daytime and which fresh cut timber has to stand if being stored in an open yard for one week before being kilndried. By comparing these results with the ones obtained after continuous freezing at -250C for one week, it was established that the temperature variation and the repeated changing phase of water inside wood increase dimensional instability and reduce the mechanical strengths much more than the simple exposure to theconstant negative temperature.

  20. 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.

  1. 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.

  2. Viral impacts on microbial carbon cycling in thawing permafrost soils

    Science.gov (United States)

    Trubl, G. G.; Roux, S.; Bolduc, B.; Jang, H. B.; Emerson, J. B.; Solonenko, N.; Li, F.; Solden, L. M.; Vik, D. R.; Wrighton, K. C.; Saleska, S. R.; Sullivan, M. B.; Rich, V. I.

    2017-12-01

    Permafrost contains 30-50% of global soil carbon (C) and is rapidly thawing. While the fate of this C is unknown, it will be shaped in part by microbes and their associated viruses, which modulate host activities via mortality and metabolic control. To date, viral research in soils has been outpaced by that in aquatic environments, due to the technical challenges of accessing viruses as well as the dramatic physicochemical heterogeneity in soils. Here, we describe advances in soil viromics from our research on permafrost-associated soils, and their implications for associated terrestrial C cycling. First, we optimized viral resuspension-DNA extraction methods for a range of soil types. Second, we applied cutting-edge viral-specific informatics methods to recover viral populations, define their gene content, connect them to potential hosts, and analyze their relationships to environmental parameters. A total of 781 viral populations were recovered from size-fractionated virus samples of three soils along a permafrost thaw gradient. Ecological analyses revealed endemism as recovered viral populations were largely unique to each habitat and unlike those in aquatic communities. Genome- and network-based classification assigned these viruses into 226 viral clusters (VCs; genus-level taxonomy), 55% of which were novel. This increases the number of VCs by a third and triples the number of soil viral populations in the RefSeq database (currently contains 256 VCs and 316 soil viral populations). Genomic analyses revealed 85% of the genes were functionally unknown, though 5% of the annotatable genes contained C-related auxiliary metabolic genes (AMGs; e.g. glycoside hydrolases). Using sequence-based features and microbial population genomes, we were able to in silico predict hosts for 30% of the viral populations. The identified hosts spanned 3 phyla and 6 genera but suggested these viruses have species-specific host ranges as >80% of hosts for a given virus were in the same

  3. 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...

  4. Rapid stabilization of thawing soils For enhanced vehicle mobility: a field demonstration project

    Science.gov (United States)

    1999-02-01

    Thawing soil presents a formidable challenge for vehicle operations cross-country and on unsurfaced roads. To mitigate the problem, a variety of stabilization techniques were evaluated for their suitability for rapid employment to enhance military ve...

  5. 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...

  6. 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.

  7. 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...

  8. Prediction model for carbonation depth of concrete subjected to freezing-thawing cycles

    Science.gov (United States)

    Xiao, Qian Hui; Li, Qiang; Guan, Xiao; Xian Zou, Ying

    2018-03-01

    Through the indoor simulation test of the concrete durability under the coupling effect of freezing-thawing and carbonation, the variation regularity of concrete neutralization depth under freezing-thawing and carbonation was obtained. Based on concrete carbonation mechanism, the relationship between the air diffusion coefficient and porosity in concrete was analyzed and the calculation method of porosity in Portland cement concrete and fly ash cement concrete was investigated, considering the influence of the freezing-thawing damage on the concrete diffusion coefficient. Finally, a prediction model of carbonation depth of concrete under freezing-thawing circumstance was established. The results obtained using this prediction model agreed well with the experimental test results, and provided a theoretical reference and basis for the concrete durability analysis under multi-factor environments.

  9. 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...

  10. 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...

  11. 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...

  12. 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.

  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

    superoxide dismutase to compensate for the lack of the cytoplasmic enzyme. Free radicals generated as a result of freezing and thawing were detected in cells directly using electron paramagnetic resonance spectroscopy with either alpha-phenyl-N-tert-butylnitrone or 5, 5-dimethyl-1-pyrroline-N-oxide as spin...... the sod1 mutant could be made more resistant by treatment with the superoxide anion scavenger MnCl2, or by freezing in the absence of oxygen, or by the generation of a rho0 petite. Increased expression of SOD2 conferred freeze-thaw tolerance on the sod1 mutant indicating the ability of the mitochondrial...

  14. 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.

  15. 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.

  16. 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.

  17. Freeze-Thaw Cycles and Soil Biogeochemistry: Implications for Greenhouse Gas emission

    Science.gov (United States)

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

    2016-12-01

    Freeze-thaw cycles represent a major natural climate forcing acting on soils at middle and high latitudes. Repeated freezing and thawing of soils changes their physical properties, geochemistry, and microbial community structure, which together govern the biogeochemical cycling of carbon and nutrients. In this presentation, we focus on how freeze-thaw cycles regulate carbon and nitrogen cycling and how these transformations influence greenhouse gas (GHG) fluxes. We present a novel approach, which combines the acquisition of physical and chemical data in a newly developed experimental soil column system. This system simulates realistic soil temperature profiles during freeze-thaw cycles. A high-resolution, Multi-Fiber Optode (MuFO) microsensor technique was used to detect oxygen (O2) continuously in the column at multiple depths. Surface and subsurface changes to gas and aqueous phase chemistry were measured to delineate the pathways and quantify soil respiration rates during freeze-thaw cycles. The results indicate that the time-dependent release of GHG from the soil surface is influenced by a combination of two key factors. Firstly, fluctuations in temperature and O2 availability affect soil biogeochemical activity and GHG production. Secondly, the recurrent development of a physical ice barrier prevents exchange of gaseous compounds between the soil and atmosphere during freezing conditions; removal of this barrier during thaw conditions increases GHG fluxes. During freezing, O2 levels in the unsaturated zone decreased due to restricted gas exchange with the atmosphere. As the soil thawed, O2 penetrated deeper into the soil enhancing the aerobic mineralization of organic carbon and nitrogen. Additionally, with the onset of thawing a pulse of gas flux occurred, which is attributed to the build-up of respiratory gases in the pore space during freezing. The latter implies enhanced anaerobic respiration as O2 supply ceases when the upper soil layer freezes.

  18. 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.

  19. 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.

  20. Superplasticizer effect on cement paste structure and concrete freeze-thaw resistance

    Science.gov (United States)

    Shuldyakov, Kirill; Kramar, Lyudmila; Trofimov, Boris; Ivanov, Ilya

    2016-01-01

    Article presents the results of studies of various types of superplasticizer additives and their influence on concrete structure and resistance under cyclic freezing-thawing. Glenium ACE 430 was taken as a polycarboxylate superplasticizer, and SP-1 - as a naphthalene-formaldehyde superplasticizer. It is revealed that at identical structure, W/C and fluidity of concrete mix, application of the polycarboxylate superplasticizer, Glenium AC 430, in comparison to the naphthalene-formaldehyde one SP-1, facilitates the increase of the concrete grade in freeze and thaw resistance from F2300 to F2400, concrete freeze and thaw resistance can be possible even higher if the gravel with higher freeze and thaw resistance is applied. To assess the superplasticizers influence on cement paste structure tests of the phase composition of the cement paste of the studied concrete were conducted. It is established that the use of polycarboxylate superplasticizer together with silica fume facilitates formation of cement plaster structure from tobermorite gel. This gel has increased basicity and is resistant to crystallization due to cyclic freezing. It is shown that in the presence of SP-1+SF in the cement paste of concrete during hydration the structure of hydrosilicate phases preferably comprises of C-S-H(I) and C-S-H(II) phases which actively crystallize while cyclic freezing and thawing and reduce freeze-thaw resistance of concrete.

  1. Effects of Thawing on Frozen Semen Quality of Limousin and Brahman Bulls

    Directory of Open Access Journals (Sweden)

    wc Pratiwi

    2009-01-01

    Full Text Available The success of Artificial Insemination (AI influenced by many factor, there are nutrition, body condition and post thawing motility (PTM. The PTM influenced by liquid N2 storage, equilibration temperature and handling straw. The purpose of this research to compare the effect of thawing duration to frozen semen quality of Limousin and Brahman. This research was done in BIBD, Agriculture Official of Blora, Central Java and Laboratory of Beef Cattle Station Research, Grati. As semen source is bull of Limousin and Brahman with age 2-3 years, body weight + 1200 kg. The data was observed such as: (1 pH, (2 Motility, (3 Live sperm, (4 Abnormality. The research use Randomized Complete Design (RCD one way there are time of thawing 0, 15, 30, 45 minutes with 10 time repetition. The result of this research showed that the highest motility and live sperm (P<0,05 at the treatment with the duration of thawing 0 minute, there are 41,50% and 66,50% (Limousin frozen semen; 40,00% and 39,58% (Brahman frozen semen. It was concluded that shortening the time of thawing could be repairing the PTM and S/C value. (Animal Production 11(1: 48-52 (2009 Key Words : semen quality, frozen semen, thawing

  2. Permafrost carbon loss and chemical changes associated with thaw slumps in the northern Qinghai Tibetan Plateau

    Science.gov (United States)

    Mu, C.

    2015-12-01

    Permafrost thaw causes ground subsidence or thermokarst. Thermokarst terrain on hilly slopes can lead to the formation of thaw slumps, which dramatically alter soil properties and carbon emissions, but little is known regarding the effects of thaw slumps on the biogeochemical processes of soil carbon. In the present study, we measured the soil carbon contents and physiochemical properties in different thaw slump stages (no slump, slumping and slumped) in the upper reach of the Heihe River Basin in the northeastern Qinghai Tibetan Plateau (QTP). With these samples, the C mineralization rates were measured using laboratory incubations. Meanwhile, the chemistry changes of organic matter were examined using Fourier transform infrared (FTIR) spectroscopy analyzer before and after the incubation. The results showed that there was a significant decrease in soil carbon and nitrogen stocks in the slumping and slumped stages. The loss of organic carbon and total nitrogen was 29.6 ± 5.9% and 31.1 ± 8.8% in the upper 0-10 cm layer of the slumping soil compared to the no slump soil. The slumped soil had a significantly lower loss of carbon and nitrogen content than the slumping soil (t-test, p production than that of slumping soil (t-test, p chemical structure and characteristics. These results demonstrate that thaw slump plays an important role in the impact of permafrost thaw on chemical characteristics of organic matter and merits greater attention.

  3. 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.

  4. Non-invasive metabolomic profiling of embryo culture media and morphology grading to predict implantation outcome in frozen-thawed embryo transfer cycles.

    Science.gov (United States)

    Li, Xiong; Xu, Yan; Fu, Jing; Zhang, Wen-Bi; Liu, Su-Ying; Sun, Xiao-Xi

    2015-11-01

    Assessment of embryo viability is a crucial component of in vitro fertilization and currently relies largely on embryo morphology and cleavage rate. Because morphological assessment remains highly subjective, it can be unreliable in predicting embryo viability. This study investigated the metabolomic profiling of embryo culture media using near-infrared (NIR) spectroscopy for predicting the implantation potential of human embryos in frozen-thawed embryo transfer (FET) cycles. Spent embryo culture media was collected on day 4 after thawed embryo transfer (n = 621) and analysed using NIR spectroscopy. Viability scores were calculated using a predictive multivariate algorithm of fresh embryos with known pregnancy outcomes. The mean viability indices of embryos resulting in clinical pregnancy following FET were significantly higher than those of non-implanted embryos and differed between the 0, 50, and 100 % implantation groups. Notably, the 0 % group index was significantly lower than the 100 % implantation group index (-0.787 ± 0.382 vs. 1.064 ± 0.331, P  0.05). NIR metabolomic profiling of thawed embryo culture media is independent of morphology and correlates with embryo implantation potential in FET cycles. The viability score alone or in conjunction with morphologic grading is a more objective marker for implantation outcome in FET cycles than morphology alone.

  5. Cumulative evidence of the low reliability of frozen/thawed pig skin as a model for in vitro percutaneous permeation testing.

    Science.gov (United States)

    Sintov, Amnon C

    2017-05-01

    Porcine skin has frequently been used as a model in in vitro permeation studies being considered as an excellent alternative for human skin due to biochemical similarities. The use of frozen skin after thawing is particularly more convenient for these studies since it is available whenever needed. Even though several researchers have noticed that freezing and then thawing the tissue result in enhancement of drug permeation, many published articles have still described studies using frozen pig skin for bioequivalence and transdermal evaluation of drug products. The aim of this commentary article is therefore to explicitly demonstrate, according to our experience, the low-reliability of the convenient protocol of freezing pig skin for in vitro percutaneous studies. It has been shown in three separate studies using three different drugs that frozen/thawed pig skin had a higher permeability to drugs compared to that obtained by using fresh skin. The results have further demonstrated that the abnormal permeability through frozen pig skin is independent of the effect of different formulations, placing a question mark on the validity of the not freshly-used porcine skin for in vitro penetration studies. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Conception Rate and Litter Size in Multiparous Sows after Intrauterine Insemination Using Frozen-Thawed Boar Semen in a Commercial Swine Herd in Thailand

    Science.gov (United States)

    CHANAPIWAT, Panida; OLANRATMANEE, Em-On; KAEOKET, Kampon; TUMMARUK, Padet

    2014-01-01

    ABSTRACT The aim of the present study was to determine the conception rate and litter size in sows after fixed time intra-uterine insemination using frozen-thawed boar semen in a commercial swine herd in Thailand. Sixty-nine Landrace multiparous sows were randomly allocated into two groups, including control (n=36) and treatment (n=33). The control sows were inseminated with extended fresh semen (3 × 109 motile sperm/dose, 100 ml) at 24, 36 and 48 hr after the onset of estrus. The treatment sows were inseminated with frozen-thawed semen (2 × 109 motile sperm/dose, 20 ml) at 24 and 36 hr after induction of ovulation by human chorionic gonadotropin. All inseminations were carried out by using an intra-uterine insemination technique. The time of ovulation was determined by using transrectal real-time B-mode ultrasonography. The conception rate, farrowing rate, total number of piglets born/litter (TB) and number of piglets born alive/litter (BA) were evaluated. The sows inseminated with extended fresh semen yield a higher TB (10.8 versus 9.0 piglets/l, P=0.015) and tended to have a higher conception rate (88.9% versus 75.8%, P=0.150) than sows inseminated with frozen-thawed semen. In conclusion, insemination using frozen-thawed boar semen can be practiced with convinced fertility under field conditions by fixed-time intrauterine insemination with 2 × 109 sperm/ dose of 20 ml at 24 and 36 hr after the onset of estrus. PMID:24954517

  7. 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

  8. Freeze and Thaw of CD4+CD25+Foxp3+ Regulatory T Cells Results in Loss of CD62L Expression and a Reduced Capacity to Protect against Graft-versus-Host Disease.

    Directory of Open Access Journals (Sweden)

    Mareike Florek

    Full Text Available The adoptive transfer of CD4+CD25+Foxp3+ regulatory T cells (Tregs in murine models of allogeneic hematopoietic cell transplantation (HCT has been shown to protect recipient mice from lethal acute graft-versus-host disease (GVHD and this approach is being actively investigated in human clinical trials. Here, we examined the effects of cryopreservation on Tregs. We found that freeze and thaw of murine and human Tregs is associated with reduced expression of L-selectin (CD62L, which was previously established to be an important factor that contributes to the in vivo protective effects of Tregs. Frozen and thawed murine Tregs showed a reduced capacity to bind to the CD62L binding partner MADCAM1 in vitro as well as an impaired homing to secondary lymphoid organs in vivo. Upon adoptive transfer frozen and thawed Tregs failed to protect against lethal GVHD compared with fresh Tregs in a murine model of allogeneic HCT across major histocompatibility barriers. In summary, the direct administration of adoptively transferred frozen and thawed Tregs adversely affects their immunosuppressive potential which is an important factor to consider in the clinical implementation of Treg immunotherapies.

  9. 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.

  10. 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.

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

    Science.gov (United States)

    Thongtip, Nikorn; Mahasawangkul, Sittidet; Thitaram, Chatchote; Pongsopavijitr, Pornsawan; Kornkaewrat, Kornchai; Pinyopummin, Anuchai; Angkawanish, Taweepoke; Jansittiwate, Saran; Rungsri, Ronnachit; Boonprasert, Khajornpat; Wongkalasin, Warut; Homkong, Pongpon; Dejchaisri, Suthathip; Wajjwalku, Worawit; Saikhun, Kulnasan

    2009-01-01

    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. PMID:19615097

  12. 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.

  13. Nitrogen availability drives priming effect by altering microbial carbon-use efficiency after permafrost thaw

    Science.gov (United States)

    Chen, L.; Liu, L.; Zhang, Q.; Mao, C.; Liu, F.; Yang, Y.

    2017-12-01

    Enhanced vegetation growth can potentially aggravate soil C loss by accelerating the decomposition of soil organic matter (SOM) ("priming effect"), thereby reinforcing the positive C-climate feedback in permafrost ecosystems. However, the degree to which priming effect alters permafrost C dynamics is expected to be modified by nitrogen (N) availability after permafrost thaw. Despite this recognition, experimental evidence for the linkage between priming effect and post-thaw N availability is still lacking. Particularly, the microbial mechanisms involved remain unknown. Here, using a thermokarst-induced natural N gradient combined with an isotope-labeled glucose and N addition experiment, we presented a strong linkage between soil N availability and priming effect in Tibetan permafrost. We observed that the magnitude of priming effect along the thaw gradient was negatively associated with soil total dissolved nitrogen (TDN) concentration. This negative effect of post-thaw N availability was further proved by a sharply reduced priming effect following mineral N supply. These two lines of evidence jointly illustrated that the priming effect along the thaw chronosequence was controlled by N availability, supporting the `N mining theory'. In contrast to the prevailing assumption, this N-regulated priming effect was independent from changes in C- or N-acquiring enzyme activities, but positively associated with the change in metabolic quotients (△SOM-qCO2), highlighting that decreased microbial metabolism efficiency rather than increased enzyme activities account for greater priming effect under reduced N availability. Taken together, these findings demonstrate that C dynamics in melting permafrost largely depends on post-thaw N availability due to its effect of retarding SOM mineralization. This C-N interaction and the relevant microbial metabolic efficiency should be considered in Earth System Models for a better understanding of soil C dynamics after permafrost thaw.

  14. Effect of freeze-thaw cycles on greenhouse gas fluxes from peat soils

    Science.gov (United States)

    Oh, H. D.; Rezanezhad, F.; Markelov, I.; McCarter, C. P. R.; Van Cappellen, P.

    2017-12-01

    The ongoing displacement of climate zones by global warming is increasing the frequency and intensity of freeze-thaw cycles in middle and high latitude regions, many of which are dominated by organic soils such as peat. Repeated freezing and thawing of soils changes their physical properties, geochemistry, and microbial community structure, which together govern the biogeochemical cycling of carbon and nutrients. In this presentation, we focus on how freeze-thaw cycles influence greenhouse gas fluxes from peat using a newly developed experimental soil column system that simulates realistic soil temperature profiles during freeze-thaw cycles. We measured the surface and subsurface changes to gas and aqueous phase chemistry to delineate the diffusion pathways and quantify soil greenhouse gas fluxes during freeze-thaw cycles using sulfur hexafluoride (SF6) as a conservative tracer. Three peat columns were assembled inside a temperature controlled chamber with different soil structures. All three columns were packed with 40 cm of undisturbed, slightly decomposed peat, where the soil of two columns had an additional 10 cm layer on top (one with loose Sphagnum moss and one with an impermeable plug). The results indicate that the release of SF6 and CO2 gas from the soil surface was influenced by the recurrent development of a physical ice barrier, which prevented gas exchange between the soil and atmosphere during freezing conditions. With the onset of thawing a pulse of SF6 and CO2 occurred, resulting in a flux of 3.24 and 2095.52 µmol/m2h, respectively, due to the build-up of gases in the liquid-phase pore space during freezing. Additionally, we developed a model to determine the specific diffusion coefficients for each peat column. These data allow us to better predict how increased frequency and intensity of freeze-thaw cycles will affect greenhouse gas emissions in northern peat soils.

  15. Patterns of nitrogen export from a seasonal freezing agricultural watershed during the thawing period.

    Science.gov (United States)

    Zhao, Qiang; Chang, Dan; Wang, Kang; Huang, Jiesheng

    2017-12-01

    The objectives of this study were to investigate water, ammonium nitrogen (NH 4 + -N), and nitrate nitrogen (NO 3 - -N) export processes during the thawing period in a watershed with heavy agricultural activities and to evaluate contributions of N (i.e., NO 3 - -N and NH 4 + -N) from different source areas under different climate conditions. Experiments were conducted within the 75km 2 agricultural Heidingzi watershed in northeast China. The thawing period was divided into four stages: early-melt, late-melt, rain-on-melt, and post-melt. Drainage regions (DRs) were separated into three types. The processes of water and N discharge from soil into rivers were monitored in these DRs during the thawing periods of 2014, 2015, and 2016. Results show that the processes of water and N discharge were not synchronous during the thawing period. Variations in discharge concentrations of NH 4 + -N and NO 3 - -N during the thawing period were mainly affected by the flushing effect, which was controlled by the physical state of the surface water (snow or ice) and the melt rate of frozen soil. Contributions of N export from the DRs varied under different land uses and climate conditions during the thawing period. NO 3 - -N export was mainly from maize fields. Thawing stages with high NO 3 - -N export were always accompanied by higher discharge rates. NH 4 + -N export mainly occurred during the early-melt and late-melt stages and from riverside rural regions. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. 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.

  17. 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.

  18. 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.

  19. Experimental Study and Numerical Simulation of Seismic Behavior for RC Columns Subjected to Freeze-Thaw Cycles

    OpenAIRE

    Qing Qin; Shansuo Zheng; Lei Li; Liguo Dong; Yixin Zhang; Sha Ding

    2017-01-01

    Freeze-thaw of concrete is significantly responsible for serious damage to RC buildings, which may result in premature failure with little warning. Therefore, it is necessary to consider the effects of freeze-thaw environment when assessing seismic performance for RC structures. In this study, pseudo-static experiments of four RC columns were conducted in terms of different number of freeze-thaw cycles (FTCs). The results showed that the FTCs had an influence on the bearing capacity, ductilit...

  20. 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

    of prognostic factors showed that more retrieved oocytes were associated with a significantly higher CLBR in both treatment groups. For the subgroup of obese women (BMI >30 kg/m2), the CLBR was significantly higher in the GnRH-antagonist group (P = 0.02). LIMITATIONS, REASONS FOR CAUTION: The duration......, 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...... of the trial is a possible limitation with introduction of new methods as 'Freeze all' and 'GnRH-agonist triggering', but as these treatments were used in only few women, a systematic bias is not likely. Blastocyst culture of surplus embryos for freezing was introduced to both groups simultaneously, thereby...

  1. Evaluating the freeze-thaw durability of portland cement-stabilized-solidified heavy metal waste using acoustic measurements

    International Nuclear Information System (INIS)

    El-Korchi, T.; Gress, D.; Baldwin, K.; Bishop, P.

    1989-01-01

    The use of stress wave propagation to assess freeze-thaw resistance of portland cement solidified/stabilized waste is presented. The stress wave technique is sensitive to the internal structure of the specimens and would detect structural deterioration independent of weight loss or visual observations. The freeze-thaw resistance of a cement-solidified cadmium waste and a control was evaluated. The control and cadmium wastes both showed poor freeze-thaw resistance. However, the addition of cadmium and seawater curing increased the resistance to more cycles of freezing and thawing. This is attributed to microstructural changes

  2. 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.

  3. Monitoring Freeze Thaw Transitions in Arctic Soils using Complex Resistivity Method

    Science.gov (United States)

    Wu, Y.; Hubbard, S. S.; Ulrich, C.; Dafflon, B.; Wullschleger, S. D.

    2012-12-01

    The Arctic region, which is a sensitive system that has emerged as a focal point for climate change studies, is characterized by a large amount of stored carbon and a rapidly changing landscape. Seasonal freeze-thaw transitions in the Arctic alter subsurface biogeochemical processes that control greenhouse gas fluxes from the subsurface. Our ability to monitor freeze thaw cycles and associated biogeochemical transformations is critical to the development of process rich ecosystem models, which are in turn important for gaining a predictive understanding of Arctic terrestrial system evolution and feedbacks with climate. In this study, we conducted both laboratory and field investigations to explore the use of the complex resistivity method to monitor freeze thaw transitions of arctic soil in Barrow, AK. In the lab studies, freeze thaw transitions were induced on soil samples having different average carbon content through exposing the arctic soil to temperature controlled environments at +4 oC and -20 oC. Complex resistivity and temperature measurements were collected using electrical and temperature sensors installed along the soil columns. During the laboratory experiments, resistivity gradually changed over two orders of magnitude as the temperature was increased or decreased between -20 oC and 0 oC. Electrical phase responses at 1 Hz showed a dramatic and immediate response to the onset of freeze and thaw. Unlike the resistivity response, the phase response was found to be exclusively related to unfrozen water in the soil matrix, suggesting that this geophysical attribute can be used as a proxy for the monitoring of the onset and progression of the freeze-thaw transitions. Spectral electrical responses contained additional information about the controls of soil grain size distribution on the freeze thaw dynamics. Based on the demonstrated sensitivity of complex resistivity signals to the freeze thaw transitions, field complex resistivity data were collected over

  4. 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

  5. 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

  6. Review of Thawing Time Prediction Models Depending on Process Conditions and Product Characteristics

    Directory of Open Access Journals (Sweden)

    Walter E. L. Spiess

    2016-01-01

    Full Text Available Determining thawing times of frozen foods is a challenging problem as the thermophysical properties of the product change during thawing. A number of calculation models and solutions have been developed. The proposed solutions range from relatively simple analytical equations based on a number of assumptions to a group of empirical approaches that sometimes require complex calculations. In this paper analytical, empirical and graphical models are presented and critically reviewed. The conditions of solution, limitations and possible applications of the models are discussed. The graphical and semi-graphical models are derived from numerical methods. Using the numerical methods is not always possible as running calculations takes time, whereas the specialized software and equipment are not always cheap. For these reasons, the application of analytical-empirical models is more useful for engineering. It is demonstrated that there is no simple, accurate and feasible analytical method for thawing time prediction. Consequently, simplified methods are needed for thawing time estimation of agricultural and food products. The review reveals the need for further improvement of the existing solutions or development of new ones that will enable accurate determination of thawing time within a wide range of practical conditions of heat transfer during processing.

  7. 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.

  8. Effect of repeated freezing-thawing on the Achilles tendon of rabbits.

    Science.gov (United States)

    Chen, Lianxu; Wu, Yanping; Yu, Jiakuo; Jiao, Zhaode; Ao, Yingfang; Yu, Changlong; Wang, Jianquan; Cui, Guoqing

    2011-06-01

    The increased use of allograft tissue in the reconstruction of anterior cruciate ligament has brought more focus to the effect of storage and treatment on allograft. The purpose of this study was to observe the effect of histology and biomechanics on Achilles tendon in rabbits through repeated freezing-thawing before allograft tendon transplantation. Rabbit Achilles tendons were harvested and processed according to the manufacture's protocol of tissue bank, and freezing-thawing was repeated three times (group 1) and ten times (group 2). Those received only one cycle were used as controls. Then, tendons in each group were selected randomly to make for histological observations and biomechanics test. Histological observation showed that the following changes happened as the number of freezing-thawing increased: the arrangement of tendon bundles and collagen fibrils became disordered until ruptured, cells disrupted and apparent gaps appeared between tendon bundle because the formation of ice crystals. There were significant differences between the experimental and control groups in the values of maximum load, energy of maximum load and maximum stress, whereas no significant differences existed in other values such as stiffness, maximum strain, elastic modulus, and energy density. Therefore, repeated freezing-thawing had histological and biomechanical effect on Achilles tendon in rabbits before allograft tendon transplantation. This indicates that cautions should be taken in the repeated freezing-thawing preparation of allograft tendons in clinical application.

  9. Tolerance of jenipapo seeds to cryoprotectants and thawing after immersion in liquid nitrogen

    Directory of Open Access Journals (Sweden)

    Severino de Paiva Sobrinho

    2017-12-01

    Full Text Available The objective of this study was to evaluate the effects of two cryoprotectants followed by thawing on the physiological potential of Genipa americana L. seeds. Two experiments testing 12 treatments were conducted, one for each cryoprotectant, both in a factorial scheme of 6 × 2 (cryoprotectant concentrations × thawing methods. We tested 0, 5, 10, 15, 20, and 25% for dimethyl sulfoxide, and 0, 0.25, 0.5, 0.75, 1.0, and 1.25 M for sucrose. The thawing methods were fast (38 °C for 30 min and slow (25 °C for 4 h. The seeds were immersed in the cryoprotectant solution for 3 h, stored for 120 h, and then thawed. The seeds were then sown in substrate (sand and vermiculite, 1:1. Emergence percentage along with speed index, length, fresh and dry matter mass of seedlings were evaluated. Dimethyl sulfoxide and sucrose can be used as cryoprotectants in G. americana seeds. Thawing should be slow when treating seeds with dimethyl sulfoxide.

  10. 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.

  11. 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 (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.

  12. 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.

  13. Three-Dimensional Microstructure of Biological Tissues during Freezing and Thawing

    Science.gov (United States)

    Ishiguro, Hiroshi; Horimizu, Takashi; Kataori, Akinobu; Kajigaya, Hiroshi

    Three-dimensional behavior of ice crystals and cells during the freezing and thawing of biological tissues was investigated microscopically in real time by using a confocal laser scanning microscope(CLSM) and a fluorescent dye, acridine orange (AO). Fresh tender meat (2nd pectoral muscles) of chicken was stained with the AO in physiological saline to distinguish ice crystals and cells by their different colors, and then frozen and thawed under two different thermal protocols: a) slow-cooling and rapid-warming and b) rapid-cooling and rapid-warming. The CLSM noninvasively produced optical tomograms of the tissues to clarify the pattern of freezing, morphology of ice crystals in the tissues, and the interaction between ice crystals and cells. Also, the tissues were morphologically investigated by pathological means after the freezing and thawing. Typical freezing pattern during the slow-cooling was extracellular-freezing, and those during the rapid-cooling were extracellular-freezing and intracellular freezing with a lot of fine ice crystals in the cells. Cracks caused by the extracellular and intracellular ice crystals remained in the muscle tissues after the thawing. The results obtained by using the CLSM/dye method were consistent with pathologically morphological changes in the tissues through freezing and thawing.

  14. Isolated total RNA and protein are preserved after thawing for more than twenty-four hours

    Science.gov (United States)

    de Oliveira, Ivone Braga; Ramos, Débora Rothstein; Lopes, Karen Lucasechi; de Souza, Regiane Machado; Heimann, Joel Claudio; Furukawa, Luzia Naôko Shinohara

    2012-01-01

    OBJECTIVE: The preservation of biological samples at a low temperature is important for later biochemical and/or histological analyses. However, the molecular viability of thawed samples has not been studied sufficiently in depth. The present study was undertaken to evaluate the viability of intact tissues, tissue homogenates, and isolated total RNA after defrosting for more than twenty-four hours. METHODS: The molecular viability of the thawed samples (n = 82) was assessed using the A260/A280 ratio, the RNA concentration, the RNA integrity, the level of intact mRNA determined by reverse transcriptase polymerase chain reaction, the protein level determined by Western blotting, and an examination of the histological structure. RESULTS: The integrity of the total RNA was not preserved in the thawed intact tissue, but the RNA integrity and level of mRNA were perfectly preserved in isolated defrosted samples of total RNA. Additionally, the level of β-actin protein was preserved in both thawed intact tissue and homogenates. CONCLUSION: Isolated total RNA does not undergo degradation due to thawing for at least 24 hours, and it is recommended to isolate the total RNA as soon as possible after tissue collection. Moreover, the protein level is preserved in defrosted tissues. PMID:22473407

  15. The Antiquity of the Cam Deformity: A Comparison of Proximal Femoral Morphology Between Early and Modern Humans.

    Science.gov (United States)

    Moats, Allison R; Badrinath, Raghav; Spurlock, Linda B; Cooperman, Daniel

    2015-08-19

    The precise etiology of cam impingement continues to be incompletely understood. The prevailing hypothesis posits that the deformity arises as a developmental injury prior to skeletal maturation. There is a possible evolutionary role, with an aspherical femoral head affording upright humans better stability. We set out to identify the antiquity of the cam deformity to better understand the comparative roles of modern behavior and evolution in its development. We used 249 physical specimens of femora from the Libben osteological collection, a set of bones from an ancient population who lived between the eighth and the eleventh century. These femora were photographed in four different orientations, and six specific proximal femoral angles were measured. The values were also compared with those from modern human femora using the Student t test, with a two-tailed p value of 0.05 denoting significance. In total, 249 femora from 175 individuals were included in the final analysis. The ages of the individuals ranged between seventeen and fifty-five years. Interobserver and intraobserver correlation was good or excellent for all variables measured. Compared with modern populations, ancient human hips were significantly more anteverted (19.96° versus 12.85°; p humans (35.33° versus 45.61°; p 50°). It appears that the cam deformity was nonexistent among ancient humans and is perhaps predominantly a product of modern-day stresses. Further clinical investigation into behavioral modifications in adolescence is warranted to potentially prevent the development of deformity and impingement. Copyright © 2015 by The Journal of Bone and Joint Surgery, Incorporated.

  16. Differentiating human versus non-human bone by exploring the nutrient foramen: implications for forensic anthropology.

    Science.gov (United States)

    Johnson, Vail; Beckett, Sophie; Márquez-Grant, Nicholas

    2017-11-01

    One of the roles of a forensic anthropologist is to assist medico-legal investigations in the identification of human skeletal remains. In some instances, only small fragments of bone may be present. In this study, a non-destructive novel technique is presented to distinguish between human and non-human long bones. This technique is based on the macroscopic and computed tomography (CT) analysis of nutrient foramina. The nutrient foramen of long bone diaphyses transmits the nutrient artery which provides much of the oxygen and nutrients to the bone. The nutrient foramen and its canal were analysed in six femora and humeri of human, sheep (Ovies aries) and pig (Sus scrofa) species. The location, position and direction of the nutrient foramina were measured macroscopically. The length of the canal, angle of the canal, circumference and area of the entrance of the foramen were measured from CT images. Macroscopic analysis revealed the femora nutrient foramina are more proximal, whereas humeri foramina are more distal. The human bones and sheep humerus conform to the perceived directionality, but the pig bones and sheep femur do not. Amongst the parameters measured in the CT analysis, the angle of the canal had a discriminatory power. This study shows the potential of this technique to be used independently or complementary to other methods in distinguishing between human and non-human bone in forensic anthropology.

  17. 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.

  18. The effect of freeze-thaw cycles on the hydraulic conductivity of compacted clay

    International Nuclear Information System (INIS)

    Waite, D.; Anderson, L.; Caliendo, J.; McFarland, M.

    1994-01-01

    A study was conducted to investigate the detrimental effects of freeze-thaw on the hydraulic conductivity of compacted clay. The purpose of this study was to determine the effect that molding water content has on the hydraulic conductivity of a compacted clay soil that is subjected to freeze-thaw cycles, and to determine the relationship between the number of freeze-thaw cycles and the hydraulic conductivity of the compacted clay soil. Clay soils compacted and frozen wet of optimum experienced an increase in hydraulic conductivity of approximately 140 fold. The hydraulic conductivity of clay compacted dry of optimum increased ten fold. These results are consistent with recent research which suggests that clay compacted wet of optimum experiences large increases in hydraulic conductivity while the hydraulic conductivity of clay compacted dry of optimum increases to a lesser extent. 12 refs., 9 figs

  19. Resveratrol and Epigallocatechin-3-gallate addition to thawed boar sperm improves in vitro fertilization.

    Science.gov (United States)

    Gadani, B; Bucci, D; Spinaci, M; Tamanini, C; Galeati, G

    2017-03-01

    Thawing is one of the most delicate process after semen cryopreservation as spermatozoa pass from a dormant metabolic stage to a sudden awakening in cellular metabolism. The rapid oxygen utilization leads to an overproduction of reactive oxygen species that can damage sperm cells, thus causing a significant decrease of fertilizing potential of frozen-thawed spermatozoa. Resveratrol (Res) is a natural grape-derived phytoalexin and Epigallocatechin-3-gallate (EGCG) is the major polyphenol in green tea (Camellia sinensis); both molecules are known to possess high levels of antioxidant activity. The objective of the present study was to assess the effect of different concentrations of Res (0.5, 1 or 2 mM; Experiment 1) or EGCG (25, 50 or 100 μM; Experiment 2) supplementation to thawing boar semen extender on sperm quality parameters (viability and acrosome integrity) and in vitro fertilization (IVF). Semen after thawing and dilution with three volumes of Beltsville Thawing Solution (BTS), was immediately divided in control group without antioxidants addition (CTR) and either Res or EGCG groups. Sperm viability and acrosome integrity were evaluated in CTR, Res or EGCG groups after 1 h of incubation at 37 °C. The addition of different doses of Res or EGCG to thawing extender for 1 h did not induce any effect on boar sperm viability and acrosome integrity. However, both Res and EGCG treated samples exhibited a significantly higher penetration rate compared with CTR when used for IVF. In particular the treatment with all the EGCG concentrations increased the penetration rate (P fertilization efficiency as compared to control (EGCG 25 μM: 40.3 ± 8.2 vs 26.8 ± 9.5, P fertilization. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. 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.

  1. 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).

  2. A Peltier-based freeze-thaw device for meteorite disaggregation

    Science.gov (United States)

    Ogliore, R. C.

    2018-02-01

    A Peltier-based freeze-thaw device for the disaggregation of meteorite or other rock samples is described. Meteorite samples are kept in six water-filled cavities inside a thin-walled Al block. This block is held between two Peltier coolers that are automatically cycled between cooling and warming. One cycle takes approximately 20 min. The device can run unattended for months, allowing for ˜10 000 freeze-thaw cycles that will disaggregate meteorites even with relatively low porosity. This device was used to disaggregate ordinary and carbonaceous chondrite regoltih breccia meteorites to search for micrometeoroid impact craters.

  3. 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.

  4. 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

    superoxide dismutase to compensate for the lack of the cytoplasmic enzyme. Free radicals generated as a result of freezing and thawing were detected in cells directly using electron paramagnetic resonance spectroscopy with either alpha-phenyl-N-tert-butylnitrone or 5, 5-dimethyl-1-pyrroline-N-oxide as spin...... of superoxide radicals formed from oxygen and electrons leaked from the mitochondrial electron transport chain....

  5. 4-D permafrost thaw observations from ambient road traffic noise and a very dense distributed fiber optic sensing array

    Science.gov (United States)

    Lindsey, N.; Dou, S.; Martin, E. R.; Wagner, A. M.; Ajo Franklin, J. B.

    2017-12-01

    How does frozen soil thaw? The answer to this question affects hydrology, ecology, climate, and human infrastructure. We are using the local ambient noise field from a road recorded on a distributed fiber optic acoustic sensing (DAS) array to monitor the evolution in seismic parameters related to the top-down permafrost thaw process in the upper 10 m. Our field experiment demonstrates the advantages of "Large N" ambient noise studies using DAS, particularly to probe near surface critical zone dynamics. Over 60 days beginning in August 2016, we made continuous seismic recordings with a >4000 channel trenched fiber optic DAS dataset above a controlled permafrost warming demonstration experiment in Fairbanks, AK. The warming experiment accelerated the state of permafrost degradation by approximately two decades in a small 15 m x 20 m area, deepening the permafrost table from 4 m to 5.5 m. Continuous seismic DAS recording of high frequency surface waves (5-30 Hz) generated by vehicles traveling along a nearby road enables our investigation of hypothesized shear wave speed and attenuation changes, which lab measurements suggest may result from decreasing shear modulus and increasing saturation. We develop daily auto- and crosscorrelation function estimates using combinations of horizontal inline, collinear, and crossline DAS sensor orientations and vertical component geophone data, and then invert for maps of Love and Rayleigh wave speed that are sensitive to the upper 30 m. Many issues related to the accuracy, stability, and repeatability of the recovered empirical Green's tensor, as well as the sensitivity of the DAS sensor network will be considered.

  6. 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.

  7. Cryopreservation of turkey semen: effects of breeding line and freezing method on post-thaw sperm quality, fertilization, and hatching

    NARCIS (Netherlands)

    Long, J.A.; Purdy, P.H.; Zuidberg, C.A.; Hiemstra, S.J.; Velleman, S.G.; Woelders, H.

    2014-01-01

    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

  8. 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 mackerel. Thawing was either done fast in 18 degrees C water for 2 h or slowly at 30 degrees C overnight. Subsequent storage was at 30 degrees C (ambient) for 36 h and 2 to 5 degrees C (refrigerated) for 12 days. The cultivation methods used were total viable counts, hydrogen sulfide producing bacteria...... time of hydrogen sulfide producing bacteria was significantly affected by both thawing methods, and further, the interaction between thawing and storage significantly affected the maximum growth rate of these bacteria. However, the maximum growth rate of Pseudomonas was higher during refrigerated...

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

    African Journals Online (AJOL)

    The motility of semen subjected only to cooling for 24 h before freezing was optimal (70.0%) for artificial insemination. Moreover, semen subjected to cooling for 7 or 24 h before and after frozen-thawed could be used still with some considerations for artificial insemination. Keywords: Stallion, semen, motility, cooling, frozen- ...

  10. 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 (changes in surface wetness and wetland area, rather than the anaerobic decomposition of previously frozen C, may determine the effect of permafrost thaw on CH4 emissions from northern peatlands.

  11. 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 ...

  12. Effects of straw mulching on soil evaporation during the soil thawing ...

    Indian Academy of Sciences (India)

    Qiang Fu

    2018-03-27

    Mar 27, 2018 ... https://doi.org/10.1007/s12040-018-0933-4. Effects of straw mulching on soil evaporation during the soil thawing period in a cold region in northeastern China. Qiang Fu*, Peiru Yan, Tianxiao Li, Song Cui and Li Peng. College of Water Conservancy & Civil Engineering, Northeast Agricultural University, ...

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

    African Journals Online (AJOL)

    mz

    2017-03-13

    Mar 13, 2017 ... known that the in vivo fertility of epididymal sperm tends to be lower than that of ejaculated ones (Papa et al.,. 2015). While cryopreservation has deleterious effects on mammalian sperm, the extent of that damage varies across species and relies heavily on sperm resilience to the freezing-thawing process ...

  14. 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.

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

    Science.gov (United States)

    Shen, Tao; Jiang, Zhong-Liang; Li, Cong-Jun; Hu, Xiao-Chen; Li, Qing-Wang

    2016-04-01

    Alpha-lipoic acid (ALA) is known to be a natural antioxidant. The aim of the present study was to evaluate the cryoprotective effect of ALA on the motility of boar spermatozoa and its antioxidant effect on boar spermatozoa during freezing-thawing. Different concentrations (2.0, 4.0, 6.0, 8.0 or 10.0 mg/ml) of ALA were added to the extender used to freeze boar semen, and the effects on the quality and endogenous antioxidant enzyme activities of frozen-thawed spermatozoa were assessed. The results indicated that the addition of ALA to the extender resulted in a higher percentage of motile spermatozoa post-thaw (P < 0.05). The activities of superoxide dismutase, lactate dehydrogenase, glutamic-oxaloacetic transaminase and catalase improved after adding ALA to the extender (P < 0.05). Artificial insemination results showed that pregnancy rate and litter size were significantly higher at 6.0 mg/ml in the ALA group than in the control group (P < 0.05). In conclusion, ALA conferred a cryoprotective capacity to the extender used for boar semen during the process of freezing-thawing, and the optimal concentration of ALA for the frozen extender was 6.0 mg/ml.

  16. Transformation between Phreatic Water and Soil Water during Freeze–Thaw Periods

    Directory of Open Access Journals (Sweden)

    Junfeng Chen

    2018-03-01

    Full Text Available During freeze–thaw periods, the exchange between shallow groundwater and soil water is unusually strong and bidirectional, which causes soil salinization and affects the accuracy of water resources assessment. The objectives of this study were to explore the laws of transformation between phreatic water and soil water through nine different groundwater table depths (GTDs and three kinds of lithologies during three successive freeze–thaw periods using field lysimeters. The results showed that phreatic evaporation increased with smaller average soil particle sizes. The differences between phreatic evaporation and recharge to groundwater (DPR and GTDs were well fitted by the semi-logarithmic model, and the regression coefficients A and B of the model were well fitted by the linear relationship with the average soil particle size. With the increase of soil particle size, the change of DPR decreased with the change rate of soil particle size. The extent of transformation between phreatic water and soil water decreased with the increase of soil particle size. During the whole freeze–thaw period, the negative value of DPR increased with an decrease in GTD. The groundwater depths of zero DPR (D-zero of sandy loam, fine sand and sandy soil during the freeze–thaw periods were 2.79 m, 2.21 m and 2.12 m, respectively. This research is significant for the prevention of soil salinization disasters and the accurate assessment of water resources.

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

    DEFF Research Database (Denmark)

    Johannesson, Björn

    2010-01-01

    Samples of concrete at different water-to-cement ratios and air contents subjected to freeze/thaw cycles with the lowest temperature at about -80 degrees C are investigated. By adopting a novel technique, a scanning calorimeter is used to obtain data from which the ice contents at different freeze...

  18. 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...

  19. Novel and traditional traits of frozen-thawed porcine sperm related to in vitro fertilization success

    Science.gov (United States)

    Cryopreserved semen allows the use of single ejaculates for repeated analyses, potentially improving in vitro fertilization (IVF) consistency by eliminating inter-ejaculate variability observed with fresh semen. However, the freezing and thawing processes result in compromised sperm function and IVF...

  20. Snow cover, freeze-thaw, and the retention of nutrients in an oceanic mountain ecosystem

    NARCIS (Netherlands)

    Wipf, Sonja; Sommerkorn, Martin; Stutter, Marc I.; Wubs, E. R. Jasper; van der Wal, René

    2015-01-01

    As the climate warms, winters with less snow and therefore more soil freeze-thaw cycles are likely to become more frequent in oceanic mountain areas. It is a concern that this might impair the soil's ability to store carbon and nutrients, and lead to increased leaching losses of dissolved C and

  1. 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,

  2. Holocene carbon stocks and carbon accumulation rates altered in soils undergoing permafrost thaw

    Science.gov (United States)

    Caitlin E. Hicks Pries; Edward A.G. Schuur; K. Grace Crummer

    2012-01-01

    Permafrost soils are a significant global store of carbon (C) with the potential to become a large C source to the atmosphere. Climate change is causing permafrost to thaw, which can affect primary production and decomposition, therefore affecting ecosystem C balance. We modeled decadal and millennial soil C inputs, decomposition constants, and C accumulation rates by...

  3. Accumulation of γ-aminobutyric acid in soybean by hypoxia germination and freeze-thawing incubation.

    Science.gov (United States)

    Yang, Runqiang; Feng, Li; Wang, Shufang; Yu, Nanjing; Gu, Zhenxin

    2016-04-01

    γ-Aminobutyric acid (GABA) can be synthesised by the GABA shunt and polyamine degradation pathway in plants under hypoxia stress and lower temperature. The hypoxia germination freeze-thawing incubation was used as a new technique for accumulating more GABA in soybean. Results showed that glutamate decarboxylase (GAD) and diamine oxidase (DAO) activity as well as GABA content increased during germination within 24 h under hypoxia. However, the contents of dry matters and protein decreased. When the hypoxia-treated sprouts were frozen at -18 °C for 12 h and thawed at 25 °C for 6 h, GABA content increased drastically to 7.21-fold of the non-frozen sprouts. Subsequently, the freeze-thawing sprouts were ground into homogenates and incubated. GABA content was 14.20-fold of the only-soaked seeds when homogenates was incubated at 45 °C for 80 min within 400 µmol L(-1) pyridoxine (VB6) (pH 6.5). The hypoxia germination freeze-thawing incubation was an effective method for accumulating GABA in soybean. During incubation, DAO was more important for GABA formation in homogenate of germinated soybean compared with GAD. © 2015 Society of Chemical Industry.

  4. Evaluation of freeze-thaw durability of pervious concrete by use of operational modal analysis

    DEFF Research Database (Denmark)

    Lund, M.S.M.; Hansen, K. K.; Brincker, R.

    2018-01-01

    was evaluated from the decrease in mass and from operational modal analysis which provides an accurate determination of the change in natural frequencies with freeze-thaw exposure. Operational modal analysis was also used to determine the Young's modulus, shear modulus, and Poisson's ratio of the pervious...

  5. FREEZE-THAW AND FIRE RESISTANCE OF GEOPOLYMER MORTAR BASED ON NATURAL AND WASTE POZZOLANS

    Directory of Open Access Journals (Sweden)

    F.Nurhayat Degirmenci

    2017-12-01

    Full Text Available The purpose of this research was to investigate the resistance of pozzolan-based geopolymer mortars subjected to high temperatures and freeze-thaw cycles. Low calcium fly ash and granulated blast furnace slag as waste pozzolans and natural zeolite as a natural pozzolan were used as base materials for producing geopolymer mortar. The other purpose the research was to study the effect of alkaline activator ratio (Na₂SiO₃/NaOH on the performance of pozzolan-based geopolymer mortar specimens subjected to extreme temperatures. The influence of high temperatures on the properties of mortars was investigated at 300°C, 600°C, and 900°C. Fire and freeze-thaw and resistance of mortars were investigated in terms of visual appearance, weight loss and residual compressive strength. The minimal values of the residual compressive strength were obtained at 900°C for all mixtures. The residual compressive strength of all specimens was lower than the values obtained for specimens not subjected to any freeze-thaw resistance test, except those containing GGBS. The Na₂SiO₃/NaOH ratios of the alkaline activator solution used to prepare the geopolymer mortars have an effect on the weight losses and residual compressive strengths of the specimens subjected to high temperatures and freeze-thaw cycles. As the Na2SiO3/NaOH ratios increased, the weight and strength losses decreased.

  6. 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...

  7. Isolation of total ribonucleic acid from fresh and frozen-thawed boar ...

    African Journals Online (AJOL)

    RNA) from raw fresh semen and frozen-thawed boar semen, using a protocol comprising the conventional TRIzol assay and a membrane-based technique, the PureLink RNA mini kit. Bioanalyzer profile revealed that the sperm RNA size ...

  8. First successful artificial insemination with frozen-thawed semen in rhinoceros.

    Science.gov (United States)

    Hermes, R; Göritz, F; Saragusty, J; Sós, E; Molnar, V; Reid, C E; Schwarzenberger, F; Hildebrandt, T B

    2009-02-01

    The first successful artificial insemination (AI) in a rhinoceros was reported in 2007 using fresh semen. Following that success, we decided to evaluate the possibility of using frozen-thawed semen for artificial insemination. Semen, collected from a 35-36 year old Southern white rhinoceros (Ceratotherium simum simum) in the UK was frozen using the directional freezing technique. This frozen semen was used in two intrauterine AI attempts on a 30 years old female rhinoceros in Hungary. The first attempt, conducted 30 days postpartum with an insemination dose of approximately 135 x 10(6) motile cells, failed. The second attempt, conducted two estrus cycles later with an insemination dose of approximately 500 x 10(6) motile cells, resulted in pregnancy and the birth of a healthy offspring. This represents the first successful AI using frozen-thawed semen in a rhinoceros, putting it among very few wildlife species in which AI with frozen-thawed semen resulted in a live birth. The incorporation of AI with frozen-thawed semen into the assisted reproduction toolbox opens the way to preserve and transport semen between distant individuals in captivity or between wild and captive populations, without the need to transport stressed or potentially disease carrying animals. In addition, cryopreserved spermatozoa, in combination with AI, are useful methods to extend the reproductive lifespan of individuals beyond their biological lifespan and an important tool for managing genetic diversity in these endangered mammals.

  9. Effects of vitrification and post-thawing interval on the cytoskeleton ...

    African Journals Online (AJOL)

    In conclusion, vitrification reduces the subsequent fertilization rate of MO, however, a prolonged post-thawing incubation period (120 min) improves survival, cleavage and blastocyst formation rates, and enhances the reorganization of MO\\'s cytoskeleton (MT and MS). Keywords: Vitrification; cytoskeleton; bovine; oocytes; ...

  10. 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...

  11. 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…

  12. Effects of straw mulching on soil evaporation during the soil thawing ...

    Indian Academy of Sciences (India)

    26

    Keywords: straw mulching, soil water evaporation, soil thawing period, freezing depth, soil liquid water content. 1. Introduction. The Songnen Plain, located in northeastern China, has 594×104 ha of cultivated land area and a grain yield of 395×108 kg. It is one of the most important food production bases in China (Yan et al.

  13. The anti-cell death FNK protein protects cells from death induced by freezing and thawing

    International Nuclear Information System (INIS)

    Sudo, Kentaro; Asoh, Sadamitsu; Ohsawa, Ikuroh; Ozaki, Daiya; Yamagata, Kumi; Ito, Hiromoto; Ohta, Shigeo

    2005-01-01

    The FNK protein, constructed from anti-apoptotic Bcl-x L with enhanced activity, was fused with the protein transduction domain (PTD) of the HIV/Tat protein to mediate the delivery of FNK into cells. The fusion protein PTD-FNK was introduced into chondrocytes in isolated articular cartilage-bone sections, cultured neurons, and isolated bone marrow mononuclear cells to evaluate its ability to prevent cell death induced by freezing and thawing. PTD-FNK protected the cells from freeze-thaw damage in a concentration-dependent manner. Addition of PTD-FNK with conventional cryoprotectants (dimethyl sulfoxide and hydroxyethyl starch) increased surviving cell numbers around 2-fold compared with controls treated only with the cryoprotectants. Notably, PTD-FNK allowed CD34 + cells among bone marrow mononuclear cells to survive more efficiently (12-fold more than the control cells) from two successive freeze-thaw cycles. Thus, PTD-FNK prevented cell death induced by freezing and thawing, suggesting that it provides for the successful cryopreservation of biological materials

  14. Illuminating Geochemical Controls of Methane Oxidation Along a Gradient of Permafrost Thaw

    Science.gov (United States)

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

    2017-12-01

    Increases in annual mean temperature in the subarctic have accelerated the thaw of organic-rich permafrost peatlands, exacerbating methane (CH4) production from microbial decomposition of peat deposits and subsequent CH4 emissions. Methanotrophic bacteria may oxidize/consume upwards of 90% of produced CH4 in some settings, pending substrate availability and environmental conditions. Redox chemistry may also control the rate of CH4 oxidation in thawing permafrost areas, particularly redox potential (Eh) and the availability of oxygen (O2) and other terminal electron receptors. We investigated potential CH4 oxidation rates across a permafrost thaw gradient in Stordalen Mire (68°21'N,18°49'E) near Abisko, Sweden. Methane oxidation rates for sites from thawing and collapsed palsa, semi-wet Sphagnum, and open-water sedge sites were determined through laboratory incubations. Peat cores were extracted from two depths at each site and incubated at in situ temperatures and CH4 concentrations. Headspace samples were collected over a 48-hour period and analyzed for CH4 concentration using flame ionization detection gas chromatography (GC-FID). Dissolved O2, Eh, and dissolved CH4 were measured in sites with porewater. Oxidation rates ranged from <0.1 to 19 μg of CH4 per gram of dry biomass per day. Eh remained positive (41.6 to 316.8 mV) with available dissolved O2 (0.3 - 5.2 mg/L) in all measurement locations down to 20cm, indicating in situ aerobic CH4 oxidation is viable across these environments. Potential CH4 oxidation rates increased with increasing dissolved CH4 concentration. Highest potential CH4 oxidation rates were found in open-water sedge sites. Eh and dissolved O2 were lowest at these sites, suggesting that methanotrophs with low-O2 demand may populate sedge areas. Furthermore, potential CH4 oxidation rates were higher at depth than at the surface in thawing palsa, suggesting CH4 oxidation may mitigate CH4 production triggered by warming in these actively

  15. Changes to the Carbon and Energy fluxes in a Northern Peatland with Thawing Permafrost

    Science.gov (United States)

    Harder, S. R.; Roulet, N. T.; Crill, P. M.; Strachan, I. B.

    2017-12-01

    The maintenance of thaw of high carbon density landscapes in the permafrost region ultimately depends of how the energy balance is partitioned as temperatures and precipitation change, yet there are comparatively few energy balance studies, especially in peatlands that contain permafrost. While permafrost peatlands are currently net sinks of carbon, as Arctic temperatures rise and permafrost thaws, the future of these ecosystems and their capacity for carbon uptake is in question. Since 2012 we have been measuring the spatially integrated CO2, energy and water vapour fluxes from the Stordalen peatland (68°22'N, 19°03'E) using eddy covariance (EC). The Stordalen peatland is a heterogeneous peatland in the discontinuous permafrost zone where permafrost thaw is actively occurring, resulting in large changes to the landscape from year to year. Areas where permafrost is present are elevated by up to 1.5 m compared to the areas where permafrost has thawed causing differences in water table depth, peat temperatures, snow distribution, vegetation community and therefore in the carbon and energy fluxes. Our EC tower is located on the edge of a permafrost peat plateau (or palsa) where one fetch measures fluxes from an area underlain by permafrost and the other fetch sees the portion of the peatland where the permafrost has thawed. Within each sector, we have an array of soil temperature and water content sensors to determine the physical characteristics of each fetch. Extensive vegetation surveys (based on plant functional types or PFTs) have also been conducted to run a footprint analysis on the flux data to complete a comparative analysis of the magnitude and variability of the carbon and energy exchanges from PFT. The footprint analysis allows us to explain the difference in energy and carbon fluxes by examining the ecological, biogeochemical and physical characteristics within each footprint. We see distinctly different energy partitioning between the fetches

  16. 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

  17. Effects of aging and freezing/thawing sequence on quality attributes of bovineMm. gluteus mediusandbiceps femoris.

    Science.gov (United States)

    Kim, Hyun-Wook; Brad Kim, Yuan H

    2017-02-01

    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. 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). 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. 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.

  18. Effects of aging and freezing/thawing sequence on quality attributes of bovine Mm. gluteus medius and biceps femoris

    Science.gov (United States)

    Kim, Hyun-Wook; Brad Kim, Yuan H.

    2017-01-01

    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. PMID:27488843

  19. Micrometeorological Measurements Reveal Large Nitrous Oxide Losses during Spring Thaw in Alberta

    Directory of Open Access Journals (Sweden)

    Thomas K. Flesch

    2018-03-01

    Full Text Available Agricultural soils in Canada have been observed to emit a large pulse of nitrous oxide (N2O gas during the spring thaw, representing a large percentage of the annual emissions. We report on three years of spring thaw N2O flux measurements taken at three Alberta agricultural sites: a crop production site (Crop, cattle winter-feeding site (WF, and a cattle winter-grazing site (WG. Soil fluxes were calculated with a micrometeorological technique based on the vertical gradient in N2O concentration above each site measured with an open-path (line-averaging FTIR gas detector. The Crop and WG sites showed a clear N2O emission pulse lasting 10 to 25 days after thawing began. During this pulse there was a strong diurnal cycle in emissions that paralleled the cycle in near-surface soil temperature. The emission pulse was less pronounced at the WF site. The average spring thaw losses (over 25 to 31 days were 5.3 (Crop, 7.0 (WF, and 8.0 (WG kg N2O-N ha−1, representing 1 to 3.5% of the annual nitrogen input to the sites. These large losses are higher than found in most previous western Canadian studies, and generally higher than the annual losses estimated from the Intergovernmental Panel on Climate Change and Canadian National Inventory Report calculations. The high N2O losses may be explained by high soil nitrate levels which promoted rapid denitrification during thawing. The application of a high resolution (temporal micrometeorological technique was critical to revealing these losses.

  20. Shallow soil moisture - ground thaw interactions and controls - Part 2: Influences of water and energy fluxes

    Science.gov (United States)

    Guan, X. J.; Spence, C.; Westbrook, C. J.

    2010-07-01

    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.

  1. 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.

  2. A practical method to detect the freezing/thawing onsets of seasonal frozen ground in Alaska

    Science.gov (United States)

    Chen, Xiyu; Liu, Lin

    2017-04-01

    Microwave remote sensing can provide useful information about freeze/thaw state of soil at the Earth surface. An edge detection method is applied in this study to estimate the onsets of soil freeze/thaw state transition using L band space-borne radiometer data. The Soil Moisture Active Passive (SMAP) mission has a L band radiometer and can provide daily brightness temperature (TB) with horizontal/vertical polarizations. We use the normalized polarization ratios (NPR) calculated based on the Level-1C TB product of SMAP (spatial resolution: 36 km) as the indicator for soil freeze/thaw state, to estimate the freezing and thawing onsets in Alaska in the year of 2015 and 2016. NPR is calculated based on the difference between TB at vertical and horizontal polarizations. Therefore, it is strongly sensitive to liquid water content change in the soil and independent with the soil temperature. Onset estimation is based on the detection of abrupt changes of NPR in transition seasons using edge detection method, and the validation is to compare estimated onsets with the onsets derived from in situ measurement. According to the comparison, the estimated onsets were generally 15 days earlier than the measured onsets in 2015. However, in 2016 there were 4 days in average for the estimation earlier than the measured, which may be due to the less snow cover. Moreover, we extended our estimation to the entire state of Alaska. The estimated freeze/thaw onsets showed a reasonable latitude-dependent distribution although there are still some outliers caused by the noisy variation of NPR. At last, we also try to remove these outliers and improve the performance of the method by smoothing the NPR time series.

  3. The effect of the freezing curve type on bull spermatozoa motility after thawing

    Directory of Open Access Journals (Sweden)

    Martina Doležalová

    2015-01-01

    Full Text Available The objective of this work was to determine the effect of selected freezing curves on spermatozoa survivability after thawing, defined by its motility. The ejaculates of nine selected sires of the same age, breed, and frequency of collecting, bred under the same breeding conditions including handling, stabling, feeding system and feeding ratio composition, were repeatedly collected and evaluated. Sperm samples of each sire were diluted using only one extender and divided into four parts. Selected four freezing curves – the standard, commercially recommended three-phase curve; a two-phase curve; a slow three-phase curve; and a fast three-phase curve, differing in the course of temperature vs time, were applied. The percentage rate of progressive motile spermatozoa above head was determined immediately after thawing, and after 30, 60, 90, and 120 min of the thermodynamic test (TDT. Moreover, average spermatozoa motility (AMOT and spermatozoa motility decrease (MODE throughout the entire TDT were evaluated. Insemination doses frozen using the simpler two-phase curve demonstrated the highest motility values (+2.97% to +10.37%; P < 0.05–0.01 immediately after thawing and during the entire TDT. Concurrently, the highest AMOT (+4.37% to +8.82%; P < 0.01 was determined. The highest spermatozoa motility values were detected after thawing doses frozen by the two-phase freezing curve in eight out of nine sires. Simultaneously, a significant effect of sire individuality was clearly confirmed. Inter-sire differences of spermatozoa motility during TDT as well as AMOT and MODE were significant (P < 0.01. The findings describing both factors of interaction indicate the necessity of individual cryopreservation of the ejaculate to increase its fertilization capability after thawing.

  4. Greenhouse gas balance over thaw-freeze cycles in discontinuous zone permafrost

    Science.gov (United States)

    Wilson, R. M.; Fitzhugh, L.; Whiting, G. J.; Frolking, S.; Harrison, M. D.; Dimova, N.; Burnett, W. C.; Chanton, J. P.

    2017-02-01

    Peat in the discontinuous permafrost zone contains a globally significant reservoir of carbon that has undergone multiple permafrost-thaw cycles since the end of the mid-Holocene ( 3700 years before present). Periods of thaw increase C decomposition rates which leads to the release of CO2 and CH4 to the atmosphere creating potential climate feedback. To determine the magnitude and direction of such feedback, we measured CO2 and CH4 emissions and modeled C accumulation rates and radiative fluxes from measurements of two radioactive tracers with differing lifetimes to describe the C balance of the peatland over multiple permafrost-thaw cycles since the initiation of permafrost at the site. At thaw features, the balance between increased primary production and higher CH4 emission stimulated by warmer temperatures and wetter conditions favors C sequestration and enhanced peat accumulation. Flux measurements suggest that frozen plateaus may intermittently (order of years to decades) act as CO2 sources depending on temperature and net ecosystem respiration rates, but modeling results suggest that—despite brief periods of net C loss to the atmosphere at the initiation of thaw—integrated over millennia, these sites have acted as net C sinks via peat accumulation. In greenhouse gas terms, the transition from frozen permafrost to thawed wetland is accompanied by increasing CO2 uptake that is partially offset by increasing CH4 emissions. In the short-term (decadal time scale) the net effect of this transition is likely enhanced warming via increased radiative C emissions, while in the long-term (centuries) net C deposition provides a negative feedback to climate warming.

  5. Effects of the technique of cryopreservation and dilution/centrifugation after thawing on the motility and vitality of spermatozoa of oligoasthenozoospermic men

    Directory of Open Access Journals (Sweden)

    Esteves Sandro C.

    2003-01-01

    Full Text Available OBJECTIVE: Comparing in human semen samples with low initial quality, the effects of 2 techniques of cryopreservation and dilution/centrifugation after thawing on the spermatic motility and vitality. MATERIALS AND METHODS: Semen samples from 15 oligo and/or asthenozoospermic individuals assisted in the infertility sector of a tertiary hospital were obtained through masturbation. The samples were divided into 2 portions of equal volume, and diluted (1:1; v/v with the cryoprotector containing glycerol (Test yolk buffer. One portion was frozen through the technique of liquid nitrogen vapor with static phases (group I - GI, while the other was frozen through a programmable biological freezer with linear speed (Planer, Kryo 10, series III (group II - GII. The following parameters were assessed before freezing and after thawing: percentage of spermatozoa with progressive motility (Prog% and percentage of live spermatozoa (Vit%. After defrosting, Prog% was assessed before and after removal of cryoprotector diluent, in different time intervals (zero, 3 h, and 24 h. The statistical analysis has been accomplished by using the non-parametric tests of Wilcoxon and Friedman. RESULTS: There was significant reduction of Prog% and Vit% from before freezing to after defrosting in both groups, I and II (p < 0.001. Values of Prog% and Vit% were not statistically different between groups, after thawing. It has been observed a significant reduction in Prog% among portions frozen with the automated technique after dilution and centrifugation for removal of cryoprotector (p = 0.006. After cryoprotector removal, Prog% has been kept unaltered, in both groups, during the first 3 hours of incubation, although being superior in group I (p = 0,04. There was a significant decrease in Prog% after 24 hours of incubation, in both groups (p < 0,01. CONCLUSION: For human semen samples with low initial quality, freezing through vapor technique or through the automated technique

  6. Effects of the technique of cryopreservation and dilution/centrifugation after thawing on the motility and vitality of spermatozoa of oligoasthenozoospermic men.

    Science.gov (United States)

    Esteves, Sandro C; Spaine, Deborah M; Cedenho, Agnaldo P; Srougi, Miguel

    2003-01-01

    Comparing in human semen samples with low initial quality, the effects of 2 techniques of cryopreservation and dilution/centrifugation after thawing on the spermatic motility and vitality. Semen samples from 15 oligo and/or asthenozoospermic individuals assisted in the infertility sector of a tertiary hospital were obtained through masturbation. The samples were divided into 2 portions of equal volume, and diluted (1:1; v/v) with the cryoprotector containing glycerol (Test yolk buffer). One portion was frozen through the technique of liquid nitrogen vapor with static phases (group I - GI), while the other was frozen through a programmable biological freezer with linear speed (Planer, Kryo 10, series III) (group II - GII). The following parameters were assessed before freezing and after thawing: percentage of spermatozoa with progressive motility (Prog%) and percentage of live spermatozoa (Vit%). After defrosting, Prog% was assessed before and after removal of cryoprotector diluent, in different time intervals (zero, 3 h, and 24 h). The statistical analysis has been accomplished by using the non-parametric tests of Wilcoxon and Friedman. There was significant reduction of Prog% and Vit% from before freezing to after defrosting in both groups, I and II (p live spermatozoa with progressive motility. The effects of dilution and centrifugation to remove the cryoprotector had a negative impact only in samples frozen through the automated technique. In both techniques, progressive motility is kept constant during the first 3 hours after thawing and removal of the cryoprotector, but is drastically diminished by the end of an incubation period of 24 hours.

  7. 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.

  8. Effects of straw mulching on soil evaporation during the soil thawing period in a cold region in northeastern China

    Science.gov (United States)

    Fu, Qiang; Yan, Peiru; Li, Tianxiao; Cui, Song; Peng, Li

    2018-04-01

    To study the effect of straw mulching on soil water evaporation, it is necessary to measure soil water evaporation under different conditions of straw mulching during the soil thawing period. A field experiment was conducted in winter, and soil evaporation was measured using a microlysimeter on bare land (LD) and 4500 (GF4500), 9000 (GF9000) and 13500 kg/hm2 (GF13500) straw mulch. The influence of different quantities of straw mulch on soil water evaporation during the thawing period was analyzed using the Mallat algorithm, statistical analysis and information cost function. The results showed that straw mulching could delay the thawing of the surface soil by 3-6 d, decrease the speed at which the surface soil thaws by 0.40-0.80 cm/d, delay the peak soil liquid water content, increase the soil liquid water content, reduce the cumulative evaporation by 2.70-7.40 mm in the thawing period, increase the range of soil evaporation by 0.04-0.10 mm in the early stage of the thawing period, and reduce the range of soil evaporation by 0.25-0.90 mm in the late stage of the thawing period. Straw mulching could reduce the range of and variation in soil evaporation and can reduce the effect of random factors on soil evaporation. When the amount of straw mulch exceeded 9000 kg/hm2, the effect of increasing the amount of straw mulch on daily soil water evaporation was small.

  9. 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.

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

    Science.gov (United States)

    Jang, Seok-Joon; Rokugo, Keitetsu; Park, Wan-Shin; Yun, Hyun-Do

    2014-01-01

    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. PMID:28788522

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

    Science.gov (United States)

    Onyango, S; Palmadottir, H; Tómason, T; Marteinsson, V T; Njage, P M K; Reynisson, E

    2016-11-01

    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 mackerel. Thawing was either done fast in 18°C water for 2 h or slowly at 30°C overnight. Subsequent storage was at 30°C (ambient) for 36 h and 2 to 5°C (refrigerated) for 12 days. The cultivation methods used were total viable counts, hydrogen sulfide-producing bacteria, and Pseudomonas . Maximum growth rate, population density, and lag time were fitted on the counts using the Baranyi model. The bacterial diversity and succession were based on sequencing of 16S rRNA amplicons, and biogenic amines were quantified on high-pressure liquid chromatography-UV. The results show that lag time of hydrogen sulfide-producing bacteria was significantly affected by both thawing methods, and further, the interaction between thawing and storage significantly affected the maximum growth rate of these bacteria. However, the maximum growth rate of Pseudomonas was higher during refrigerated storage compared with storage at ambient temperature. Total viable counts showed longer lag time and reduced growth rate under refrigerated storage. Higher bacterial diversity was correlated to slow thawing and storage at ambient temperature compared with slow thawing and refrigerated storage. Overall, Acinetobacter and Psychrobacter genera were the dominant bacterial populations. The amine levels were low and could not be differentiated along the thawing and storage approaches, despite a clear increase in bacterial load, succession, and diversity. This corresponded well with the low abundance of biogenic 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

  12. 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

  13. 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

    The effect of two months of frozen storage at -20 degrees C on the spoilage characteristics and shelf life of thawed and modified atmosphere packed (MAP) cod fillets stored at 2 degrees C was studied. Thawed MAP cod fillets were compared with fresh cod fillets stored in CO2-containing modified at...... provides a more stable product in MAP but also allows much greater flexibility for production and distribution. However, a slightly increased concentration of dimethylamine, a larger drip loss, and detection of weak frozen storage flavor were observed in the thawed MAP cod fillets....

  14. Soil thaw effects on river discharge recessions of a subarctic catchment

    Science.gov (United States)

    Ploum, Stefan; Lyon, Steve; Teuling, Ryan; van der Velde, Ype

    2017-04-01

    Thawing permafrost in circumpolar regions is likely to change subsurface hydrology. In high latitude areas continuous permafrost is expected to partially thaw leading to sporadic permafrost with deeper groundwater flow paths. Moreover, freeze-thaw cycles of the shallow subsurface are likely to increase. River discharge recession analysis can be particularly useful to understand the hydrological effects of a thawing Arctic. Here we examine river discharge recessions of the Abiskojokka, a 560 km2 watershed with sporadic permafrost, using a river discharge record of 30 years (1985 - 2015). Snow observation records were used to separate river recessions in snowmelt and snowfree periods. We found significant differences between recessions during the snowmelt and snowfree seasons. During the snowmelt, recessions were close to linear (b=1.11), while during the snowfree period, recessions were more non-linear (b=1.54). Typically, non-linearity has been found to increase with discharge magnitude, while we observed the opposite (snowfree periods tend to have lower discharges than the snowmelt periods). We explain these contrasting results by hypothesizing that increased connectivity (increasing magnitude and number of water flow paths) between groundwater and stream leads to higher non-linearity. In temperate catchments without frozen soils, connectivity tends to increase with increasing discharge. In contrast, in Arctic systems, where soils are frozen, connectivity between groundwater and stream is limited. Therefore, thawing of frozen soils is expected to increase connectivity and thus non-linearity of river discharges. We tested this hypothesis with a detailed analysis of all spring flood recessions. Years with cold soil temperatures (b=1.08) and years with a below median snowpack depth were found to have progressively linear slopes (b=1.08 and 1.01 respectively). On the other hand, years with warm soil conditions show increasingly non-linear recessions (b=1.67). Although

  15. IN VITRO CULTURE OF FROZEN AND THAWED MOUSE OVA

    OpenAIRE

    KANAGAWA, Hiroshi

    1980-01-01

    Seventy mouse ova at the 4--8-cell stages were collected at room temperature from mice treated with pregnant mare's serum gonadotrophin and human chorionic gonadotrophin. Seventy ova were divided into 5 groups, and each group was placed in a 0.5 ml plastic straw with 0.2 ml of Brinster's medium. Then, the straws were immersed into an ice bath (0℃) for 5 minutes. Next, an equal volume of 2 M dimethyl sulfoxide was added to the sample straw. The medium with ova was then seeded at -6℃ and cooled...

  16. 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)...

  17. Protein degradation and phosphorylation after freeze thawing result in spermatozoon dysfunction.

    Science.gov (United States)

    Yuan, Jing

    2014-02-01

    Cryopreservation is widely used in many assisted conception units. Semen cryopreservation is the only proven method that offers many couples the chance to have children. However, spermatozoa are exposed to physical and chemical stressors during freezing and thawing that result in adverse changes in membrane lipid composition, sperm motility, viability, and acrosome status. Wang et al. (Proteomics 2014, 14, 298-310) evaluate the protein content of freeze-thawed sperm samples relative to that of fresh sperm samples from the same normozoospermic donors. Four proteins are verified via Western blot and immunofluorescent staining, which are putatively involved in spermatozoon dysfunction. These marked differences demonstrated by Wang et al. suggest that dysfunctional spermatozoon after cryopreservation may be due to protein degradation and protein phosphorylation. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Resilience of Floating Treatment Wetlands to Repeated Freeze-Thaw Cycles

    Science.gov (United States)

    Ortega, K.; Marchetto, P.; Magner, J.

    2017-12-01

    Floating treatment wetlands (FTWs), made of a matrix of recycled polyethylene terephthalate (PET) fibers, are currently being used as a method to reduce nutrient loading in lakes. The matrix encourages growth of biofilms, which uptake nutrients from the water. However, the usefulness of FTWs has only been assessed in areas where the lakes do not freeze over in the winter. Repeated freeze-thaw cycles were run on sections of the FTWs in a laboratory setting in order to test the resilience of the PET fibers over the FTWs' advertised fifteen-year lifespan. Preliminary findings suggest that the stresses caused by freezing and thawing of the surrounding water contribute to deterioration of the PET fibers, leading to production of microplastics. Estimations indicate that approximately 0.063% of a FTW's mass could be lost as microplastics over the course of its lifespan. Production of microplastics contributes to plastic pollution in the treatment water, possibly offsetting any nutrient remediation the FTWs perform.

  19. The Effect of Oxidative Stress on Thawed Bulk-Sorted Red Deer Sperm.

    Science.gov (United States)

    Anel-López, L; García-Álvarez, O; Parrilla, I; Del Olmo, D; Fernández-Santos, M R; Soler, A J; Maroto-Morales, A; Ortiz, J A; Alkmin, D V; Tarantini, T; Roca, J; Martínez, E A; Vazquez, J M; Garde, J J

    2016-06-01

    The aims of this study were to assess the effects of the sex-sorting process on post-thaw sperm quality as well as on induced oxidative stress damage (H2 O2 0 mm = H000; H2 O2 50 mm = H050; H2 O2 100 mm = H100) and the protective action of reduced glutathione (GSH) and Trolox, when comparing sorted (BSS) and non-sorted (NS) red deer spermatozoa incubated at 37°C. Sperm samples from three stags were collected by electroejaculation and frozen. Immediately after thawing, sperm motility was higher (p stress than that in non-sorted sperm. Moreover, addition of GSH at 1 mm may be a good choice for maintaining the quality of stressed sperm samples, unlike Trolox, which inhibited sperm motility. © 2016 Blackwell Verlag GmbH.

  20. Effects of Polyacrylamide in Controlling of Splash Erosion from a Soil induced Freeze-Thaw Cycle

    Directory of Open Access Journals (Sweden)

    S.H.R. Sadeghi

    2016-09-01

    Full Text Available Introduction: The capability of a soil to resist erosion depends on soil-particle size and distribution, soil structure and structural stability, soil permeability, water content, organic matter content, and mineral and chemical constituents. Among many affecting factors on aforesaid characteristics, the freezing-thawing processes may considerably affects. Freeze–thaw fluctuation is a natural phenomenon that is frequently encountered by soils in the higher latitude and altitude regions in late autumn and early spring. Effects of freezing and freezing-thawing phenomena on soil erosion and sediment yield are important. Nevertheless, soil conservation under these phenomena by using different methods as well as soil amendments has not been yet considered. Surface application of anionic polyacrylamide (PAM in solution has been found to be very effective in decreasing seal formation, runoff, and erosion.PAM stabilizes soil structure due to the ability of the polymer chains to adsorb onto clay particles and bridge them together forming stable domains. This adsorption can be a result of interactions between the negatively-charged functional groups of the PAM molecules and the positively-charged edges of clay minerals, orexchangeable polycations (mainly Ca2+ acting as ‘bridges’ between the negative charges of the PAM's functional groups and the negatively- charged planar surfaces of the clay. The PAM is adsorbed on the external surfaces of the aggregates and binds soil particles far apart together, thereby were shorter and evidently less effective in enhancing increasing their resistance to splash by raindrop impact and detachment by runoff. A lot of research work focused on freezing effects in soils on aggregation or increase aggregate stability and emphasis corresponding effects. But the effects of application of soil amendments on soil induced freeze and thaw cycle have not been studied yet. Materials and Methods: The present study evaluated the

  1. Stabilization of tetanus toxoid formulation containing aluminium hydroxide adjuvant against freeze-thawing.

    Science.gov (United States)

    Solanki, Vipul A; Jain, Nishant K; Roy, Ipsita

    2011-07-29

    Exposure to subzero temperature leads to loss of vaccine potency. This can happen due to degradation of adjuvant surface and/or inactivation of the antigen. When adsorbed on aluminium hydroxide and subjected to freeze-thawing, tetanus toxoid was desorbed from the gel matrix and the preparation was found to lose its antigenicity. Analyses showed that the gel particles were denatured after freezing. When freeze-thawing was carried out in the presence of glucose, sorbitol and arginine, the degradation of gel particles was inhibited. A higher fraction of the protein could be retained on the gel. However, the antigenicity of these preparations was quite low. In the presence of trehalose, the protein could be partially retained on aluminium hydroxide. Being a cryoprotectant, trehalose was also able to inhibit the freezing-induced denaturation of tetanus toxoid, which resulted in retention of antigenicity of the adjuvanted toxoid. Copyright © 2011 Elsevier B.V. All rights reserved.

  2. SMAP Enhanced L3 Radiometer Northern Hemisphere Daily 9 km EASE-Grid Freeze/Thaw State V001

    Data.gov (United States)

    National Aeronautics and Space Administration — Daily global composite of up-to 30 half-orbit L1C_TB files and estimated binary freeze/thaw state based on passive normalized polarization ratio measurements by the...

  3. 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...

  4. CARVE: Daily Thaw State of Boreal and Arctic Alaska from AMSR-E and SSM/I, 2003-2014

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides daily 10 km resolution maps of the Alaskan and Arctic Boreal land surface state as either frozen, melting, or thawed. These data are generated...

  5. 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...

  6. 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

    indicating very small N losses relative to the magnitudes of internal transfers, suggest tight ecosystem N cycling both during and after freeze-thaw events. Furthermore, our small and subtle effects on microbial and soluble C and N pools relative to previous studies using more severe regimes, suggests......Freeze-thaw fluctuations in soil temperature may be critical events in the annual pattern of nutrient mobilisation that supplies plant growth requirements in some temperate, and most high latitude and high altitude ecosystems. We investigated the effects of two differing freeze-thaw regimes, each...... 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...

  7. Effects of curing methods and supplementary cementitious material use on freeze thaw durability of concrete containing d-cracking aggregates.

    Science.gov (United States)

    2013-12-01

    For concrete pavements in Kansas, the most effective method of increasing their sustainability is to : increase the service life. One of the principle mechanisms of concrete pavement deterioration in Kansas is : freezing and thawing damage. Some Kans...

  8. 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

    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......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...... 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...

  9. 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...

  10. Ageing of rice husk biochar along a freeze-thaw cycles

    OpenAIRE

    Miao Wei; Cheng Xiao Ying; Meng Jun; Tang Liang

    2016-01-01

    In order to elucidate the aging possess of biochar, the experiment with treatment biochar with soil were performed. For accelerating aging process, freeing-thawing cycle were conducted to simulate the changing process of the physical and chemical properties of biochar and explore the roles of biochar in the changes of the soil nutrition. Aging treatment has a significant impact on the physical and chemical properties of biochar. The pH values, element composition, oxidation of the surface, ab...

  11. 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.

  12. Global importance of soil freeze-thaw induced emissions of nitrous oxide from croplands

    Science.gov (United States)

    Wagner-Riddle, C.; Congreves, K. A.; Abalos, D.; Berg, A. A.; Brown, S. E.; Ambadan, J. T.; Gao, X.; Tenuta, M.

    2017-12-01

    Cropland soils are by far the largest anthropogenic source of nitrous oxide (N2O). Soil N2O fluxes are highly variable in time and space due to soil, weather and management drivers. In cold climates, freeze/thaw cycles can enhance soil N2O production and more than half of annual N2O emissions may be associated with thaw-related fluxes. However, the global importance of the freeze-thaw induced N2O emissions from croplands has not been estimated before. In this study, we synthesized long-term micrometeorological flux-gradient measurements from two sites in Canada (Elora, Ontario, 14 yr; Glenlea, Manitoba, 9 yr) for annual crops such as corn, soybeans, wheat, and barley receiving typical spring inorganic fertilizer applications. These data showed cumulative freezing degree days obtained from soil temperature at 5 cm depth was the best predictor for non-growing season N2O emissions (cumulative for Nov-Apr period). An exponential-plateau model fit to the data was validated with values from 11 additional sites in North America, Europe and Asia. Daily mean soil temperature from three global re-analysis models (ERA, MERRA, GLDAS) was coupled to the spatial distribution of croplands to estimate the cumulative freezing degrees days and then N2O emissions for the cropland area using the exponential-plateau model. The global total Nov-Apr N2O emissions derived were 1.07 Tg N, an average based on all three re-analysis methods, with a mean absolute error of 55%, giving a range of 0.48 to 1.66 Tg N. Compared to published agricultural (direct + indirect) emissions, the estimate freeze-thaw induced N2O emissions suggest an underestimate of global agricultural nitrous oxide emissions by 17 to 28%.

  13. Comparison of the effect of two freeze-thawing curves for porcine semen. Preliminary results

    Directory of Open Access Journals (Sweden)

    Caldevilla M

    2016-12-01

    Full Text Available Results obtained in fertility and litter size using frozen-thawed porcine semen are far from those obtained with natural service or artificial insemination of cooled semen. The objective of this study was to evaluate freeze-thawing of porcine semen comparing the traditional slow method to a rapid curve of temperature descent, using two cryoprotectants. Six males of proven fertility (n=6, r=2 were used. Semen was obtained using the gloved-hand technique and was transported to the laboratory at 17 ºC diluted in Androstar® plus. Samples were centrifuged 15 minutes at 800 g and re-diluted in: a 5% dimethylformamide, 11% lactose, 20% egg yolk, 0.5% Equex or b 3% glycerol, 11% lactose, 20% egg yolk, 0.5% Equex. The semen was frozen in 0.5 ml straws up to a final concentration of 300 millions sperm /ml using either a modified slow traditional Westendorff curve or a rapid curve. In both cases thawing was carried out at 37 ºC during 1 minute. Kinetic motility parameters were evaluated using a CASA system (ISAS v1, Proiser®, Spain. Sperm viability and acrosome status were evaluated using the FITC-PNA/PI stain. The results were analyzed using a factorial design (analysis ofvariance with two factors, with two levels for each one and using the male as a blocking factor. No interaction was observed between the parameters. No significant differences (p> 0.05 were observed between curves or between cryoprotectants neither in any of the kinetic motility parameters evaluated nor in sperm viability and acrosome status. No significant differences (p> 0.05 were observed between curves or between cryoprotectants in sperm morphology in thawed porcine semen. Taking into account the results obtained, the rapid curve would be the practical choice as it is, faster and more manageable for fieldwork in any pig farm.

  14. 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.

  15. Methane emissions from western Canadian peatland lakes: assessing interactive effects of groundwater connectivity and permafrost thaw

    Science.gov (United States)

    Kuhn, M. A.; Riechert, C.; Estop Aragones, C.; Broder, T.; Bastviken, D.; Knorr, K. H.; Olefeldt, D.

    2017-12-01

    Rising temperatures and the submergence of recently thawed permafrost into lakes has been identified as a major driver of methane (CH4) emissions in northern regions. Lakes on the vast Taiga Plains in western Canada represent a vital unknown with respect to CH4 fluxes and their sensitivity to permafrost thaw. The Taiga Plains has several characteristics that could influence magnitude and controls on lake CH4 emissions in comparison to other regions, including high soil organic carbon stores, distinct permafrost history, and complex groundwater interactions that influence availability of terminal electron acceptor concentrations among lakes. The goal of this research is to describe the similarities and differences in processes governing lake CH4 emissions between western Canada and other northern regions. We carried out biweekly diffusive and ebullition flux measurements and monitored sediment redox profiles from two lakes near the border between Alberta and the Northwest Territories. The two lakes differ in contributions of surface water and groundwater inputs, respectively. Floating chamber-based fluxes were measured leading from the edges to the centers of the lakes from ice-out in early May until ice-cover in the fall. Preliminary redox profile analyses suggest the groundwater-fed lake has extremely high concentrations of sulfides (>200 µmol L-1) down to a depth of 30 cm, while the surface water lake has little to no sulfide, but high concentrations of reduced iron (>200 µmol L-1 ). Despite high sulfide concentrations in the sediments, the groundwater-fed lake had generally higher diffusive fluxes compared to the surface water lake, but there were no differences between the center and along the actively collapsing thermokarst edges. However, ebullition fluxes were highest from a recently thawed lake edge compared to the center of the lake and stable, non-thaw influenced edges. The results of this project will help improve current regional CH4 models by

  16. 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.

  17. Improvement of post-thaw sperm survivals using liquid nitrogen vapor in a spermcasting oyster Ostrea angasi.

    Science.gov (United States)

    Hassan, Md Mahbubul; Li, Xiaoxu; Qin, Jian G

    2017-10-01

    Low survival of cryopreserved sperm impedes the application of cryopreservation technique in spermcasting oyster species. This study developed a simple method of liquid nitrogen vapor freezing to improve post-thaw sperm survival in the spermcasting oyster Ostrea angasi. The results indicate that the permeable cryoprotectants, dimethyl sulfoxide (DMSO), ethylene glycol (EG) and propylene glycol (PG) were non-toxic to sperm up to 20% concentration and 90 min exposure whereas methanol at 10% or higher was toxic to sperm for any exposure over 30 min. Among the treatments with permeable cryoprotectants, 15% EG produced the highest post-thaw sperm motility. Sperm motility was further improved by the addition of non-permeable cryoprotectants (trehalose and glucose), with 15% EG + 0.2 M trehalose resulting in the highest post-thaw sperm motility among all the combinations evaluated. The durations of 20, 30 and 60 min equilibrations produced a higher post-thaw sperm motility and plasma membrane integrity (PMI) than 10 min. Higher post-thaw motility and PMI were achieved by freezing sperm at the 8 cm height from the liquid nitrogen surface than at the 2, 4, 6, 10 or 12 cm height. Holding sperm for 10 min in liquid nitrogen vapor produced higher post-thaw motility and PMI than for 2, 5 or 20 min. The cryopreservation protocol developed in this study improved both post-thaw motility and PMI of O. angasi sperm at least 15% higher than those cryopreserved using programmable freezing method. Liquid nitrogen vapor freezing might have greater applicability in improving post-thaw sperm quality of spermcasting oyster species. Copyright © 2017 Elsevier Inc. All rights reserved.

  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. 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.

  20. Mapping of TBARS distribution in frozen-thawed pork using NIR hyperspectral imaging.

    Science.gov (United States)

    Wu, Xiang; Song, Xinglin; Qiu, Zhengjun; He, Yong

    2016-03-01

    In this study, NIR hyperspectral imaging technology was applied to determine the distribution of TBARS in frozen-thawed pork. A total of 240 fresh pork samples were assigned to 4 treatment groups (0, 1, 3, 5 frozen-thawed cycles). For each sample, a hyperspectral image (874-1734nm) was collected, followed by chemical TBARS analysis. Successive projection algorithm (SPA) was applied to choose effective wavelengths (EWs). The selected 13 EWs of the calibration set and relevant TBARS value were used as inputs of partial least squares regression (PLSR) model, yielding correlation coefficient of prediction of 0.81 and root mean square error of prediction of 0.33. The developed PLSR model were applied pixel-wise to produce chemical maps of TBARS for 24 selected samples in the prediction set. The results indicated that NIR hyperspectral imaging combined with image processing has the potential to visualize TBARS distribution in frozen-thawed pork. This technique could be useful in real-time quality monitoring in meat industry. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Methane production as key to the greenhouse gas budget of thawing permafrost

    Science.gov (United States)

    Knoblauch, Christian; Beer, Christian; Liebner, Susanne; Grigoriev, Mikhail N.; Pfeiffer, Eva-Maria

    2018-04-01

    Permafrost thaw liberates frozen organic carbon, which is decomposed into carbon dioxide (CO2) and methane (CH4). The release of these greenhouse gases (GHGs) forms a positive feedback to atmospheric CO2 and CH4 concentrations and accelerates climate change1,2. Current studies report a minor importance of CH4 production in water-saturated (anoxic) permafrost soils3-6 and a stronger permafrost carbon-climate feedback from drained (oxic) soils1,7. Here we show through seven-year laboratory incubations that equal amounts of CO2 and CH4 are formed in thawing permafrost under anoxic conditions after stable CH4-producing microbial communities have established. Less permafrost carbon was mineralized under anoxic conditions but more CO2-carbon equivalents (CO2-Ce) were formed than under oxic conditions when the higher global warming potential (GWP) of CH4 is taken into account8. A model of organic carbon decomposition, calibrated with the observed decomposition data, predicts a higher loss of permafrost carbon under oxic conditions (113 ± 58 g CO2-C kgC-1 (kgC, kilograms of carbon)) by 2100, but a twice as high production of CO2-Ce (241 ± 138 g CO2-Ce kgC-1) under anoxic conditions. These findings challenge the view of a stronger permafrost carbon-climate feedback from drained soils1,7 and emphasize the importance of CH4 production in thawing permafrost on climate-relevant timescales.

  2. 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.

  3. Potential carbon emissions dominated by carbon dioxide from thawed permafrost soils

    Science.gov (United States)

    Schädel, Christina; Bader, Martin K.-F.; Schuur, Edward A.G.; Biasi, Christina; Bracho, Rosvel; Čapek, Petr; De Baets, Sarah; Diáková, Kateřina; Ernakovich, Jessica; Estop-Aragones, Cristian; Graham, David E.; Hartley, Iain P.; Iversen, Colleen M.; Kane, Evan S.; Knoblauch, Christian; Lupascu, Massimo; Martikainen, Pertti J.; Natali, Susan M.; Norby, Richard J.; O'Donnell, Jonathan A.; Roy Chowdhury, Taniya; Šantrůčková, Hana; Shaver, Gaius; Sloan, Victoria L.; Treat, Claire C.; Turetsky, Merritt R.; Waldrop, Mark P.; Wickland, Kimberly P.

    2016-01-01

    Increasing temperatures in northern high latitudes are causing permafrost to thaw, making large amounts of previously frozen organic matter vulnerable to microbial decomposition. Permafrost thaw also creates a fragmented landscape of drier and wetter soil conditions that determine the amount and form (carbon dioxide (CO2), or methane (CH4)) of carbon (C) released to the atmosphere. The rate and form of C release control the magnitude of the permafrost C feedback, so their relative contribution with a warming climate remains unclear. We quantified the effect of increasing temperature and changes from aerobic to anaerobic soil conditions using 25 soil incubation studies from the permafrost zone. Here we show, using two separate meta-analyses, that a 10 °C increase in incubation temperature increased C release by a factor of 2.0 (95% confidence interval (CI), 1.8 to 2.2). Under aerobic incubation conditions, soils released 3.4 (95% CI, 2.2 to 5.2) times more C than under anaerobic conditions. Even when accounting for the higher heat trapping capacity of CH4, soils released 2.3 (95% CI, 1.5 to 3.4) times more C under aerobic conditions. These results imply that permafrost ecosystems thawing under aerobic conditions and releasing CO2 will strengthen the permafrost C feedback more than waterlogged systems releasing CO2 and CH4 for a given amount of C.

  4. 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.

  5. 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

    Durability studies are carried out by subjecting FRC-beams to combined mechanical and environmental load. Mechanical load is obtained by subjecting beams to 4-point bending until a predefined crack width is reached. Specimens sawn from the beams after unloading are exposed to freeze-thaw and deic......Durability studies are carried out by subjecting FRC-beams to combined mechanical and environmental load. Mechanical load is obtained by subjecting beams to 4-point bending until a predefined crack width is reached. Specimens sawn from the beams after unloading are exposed to freeze......-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...

  6. Methane Carbon Isotopic Composition Reveals Changing Production Pathways Across a Gradient of Permafrost Thaw

    Science.gov (United States)

    Rocci, K.; Burke, S. A.; Clariza, P.; Malhotra, A.; McCalley, C. K.; Verbeke, B. A.; Werner, S. L.; Roulet, N. T.; Varner, R. K.

    2017-12-01

    Methane (CH4) emission in areas of discontinuous permafrost may increase with warming temperatures resulting in a positive feedback to climate change. Characterizing the production pathways of CH4, which may be inferred by measuring carbon isotopes, can help determine underlying mechanistic changes. We studied CH4 flux and isotopic composition of porewater (δ13C-CH4) in a sub-arctic peatland in Abisko, Sweden to understand controls on these factors across a thaw gradient during four growing seasons. Methane chamber flux measurements and porewater samples were collected in July 2013, and over the growing seasons of 2014 to 2016. Samples were analyzed on a Gas Chromatograph with a Flame Ionization Detector for CH4 concentrations and a Quantum Cascade Laser for carbon isotopes. Increased emission rates and changing isotopic signatures were observed across the thaw gradient throughout the growing season. While CH4 flux increased with increases in temperature and shallower water table, δ13C-CH4 exhibited a seasonal pattern that did not correlate with measured environmental variables, suggesting dependence on other factors. The most significant controlling factor for both flux and isotopic signature was plant community composition, specifically, the presence of graminoid species. Graminoid cover increases with thaw stage so both CH4 emissions and δ13C-CH4 are likely to increase in a warmer world, suggesting a shift toward the acetoclastic pathway of methane production.

  7. Globally important nitrous oxide emissions from croplands induced by freeze-thaw cycles

    Science.gov (United States)

    Wagner-Riddle, Claudia; Congreves, Katelyn A.; Abalos, Diego; Berg, Aaron A.; Brown, Shannon E.; Ambadan, Jaison Thomas; Gao, Xiaopeng; Tenuta, Mario

    2017-03-01

    Seasonal freezing induces large thaw emissions of nitrous oxide, a trace gas that contributes to stratospheric ozone destruction and atmospheric warming. Cropland soils are by far the largest anthropogenic source of nitrous oxide. However, the global contribution of seasonal freezing to nitrous oxide emissions from croplands is poorly quantified, mostly due to the lack of year-round measurements and difficulty in capturing short-lived pulses of nitrous oxide with traditional measurement methods. Here we present measurements collected with half-hourly resolution at two contrasting cropland sites in Ontario and Manitoba, Canada, over 14 and 9 years, respectively. We find that the magnitude of freeze-thaw-induced nitrous oxide emissions is related to the number of days with soil temperatures below 0 °C, and we validate these findings with emissions data from 11 additional sites from cold climates around the globe. Based on an estimate of cropland area experiencing seasonal freezing, reanalysis model estimates of soil temperature, and the relationship between cumulative soil freezing days and emissions that we derived from the cropland sites, we estimate that seasonally frozen cropland contributes 1.07 +/- 0.59 Tg of nitrogen as nitrous oxide annually. We conclude that neglecting freeze-thaw emissions would lead to an underestimation of global agricultural nitrous oxide emissions by 17 to 28%.

  8. InSAR detects possible thaw settlement in the Alaskan Arctic Coastal Plain

    Science.gov (United States)

    Rykhus, Russell P.; Lu, Zhong

    2008-01-01

    Satellite interferometric synthetic aperture radar (InSAR) has proven to be an effective tool for monitoring surface deformation from volcanoes, earthquakes, landslides, and groundwater withdrawal. This paper seeks to expand the list of applications of InSAR data to include monitoring subsidence possibly associated with thaw settlement over the Alaskan Arctic Coastal Plain. To test our hypothesis that InSAR data are sufficiently sensitive to detect subsidence associated with thaw settlement, we acquired all Japanese Earth Resources Satellite-1 (JERS-1) L-band data available for the summers of 1996, 1997, and 1998 over two sites on the Alaska North Slope. The least amount of subsidence for both study sites was detected in the interferograms covering the summer of 1996 (2-3 cm), interferograms from 1997 and 1998 revealed that about 3 cm of subsidence occurred at the northern Cache One Lake site, and about 5 cm of subsidence was detected at the southern Kaparuk River site. These preliminary results illustrate the capacity of the L-band (24 cm) wavelength JERS-1 radar data to penetrate the short Arctic vegetation to monitor subsidence possibly associated with thaw settlement of the active layer and (or) other hydrologic changes over relatively large areas.

  9. 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.

  10. First delivery of healthy offspring after freezing and thawing of oocytes in Switzerland.

    Science.gov (United States)

    De Geyter, Maria; Steimann, Sabine; Holzgreve, Wolfgang; De Geyter, Christian

    2007-08-11

    The interest in long-term storage of uninseminated oocytes through cryopreservation has seen a recent upsurge, because it provides the potential to assist young women to postpone childbirth after having overcome a malignant disease or delaying childbirth until after management of a professional career. The low fertilisation rate of frozen/thawed oocytes in earlier feasibility trials can now be improved by using intracytoplasmic sperm injection (ICSI) for assisting the penetration of the spermatozoon through the oocyte's hardened zona pellucida. Another reason for the reported low success rates of oocyte cryopreservation in earlier studies may have been the low developmental potential of spare oocytes, which were available for experimental cryopreservation. Oocytes retrieved from supernumerary follicles in women treated with gonadotropins for ovulation induction and intrauterine insemination can be used for the optimisation of cryostorage of uninseminated oocytes. We intended to investigate to what extent the well-established and successful cryopreservation protocols for pronucleate oocytes are also applicable for the cryopreservation of uninseminated oocytes. We herewith report the first successful pregnancy and delivery of frozen/thawed oocytes in Switzerland, which were inseminated with ICSI. In unbiased treatment groups the freezing and thawing of uninseminated oocytes and pronucleate oocytes give comparable results, if the additional manipulation during ICSI was taken into account.

  11. 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.

  12. Shifts of methanogenic communities in response to permafrost thaw results in rising methane emissions and soil property changes.

    Science.gov (United States)

    Wei, Shiping; Cui, Hongpeng; Zhu, Youhai; Lu, Zhenquan; Pang, Shouji; Zhang, Shuai; Dong, Hailiang; Su, Xin

    2018-05-01

    Permafrost thaw can bring negative consequences in terms of ecosystems, resulting in permafrost collapse, waterlogging, thermokarst lake development, and species composition changes. Little is known about how permafrost thaw influences microbial community shifts and their activities. Here, we show that the dominant archaeal community shifts from Methanomicrobiales to Methanosarcinales in response to the permafrost thaw, and the increase in methane emission is found to be associated with the methanogenic archaea, which rapidly bloom with nearly tenfold increase in total number. The mcrA gene clone libraries analyses indicate that Methanocellales/Rice Cluster I was predominant both in the original permafrost and in the thawed permafrost. However, only species belonging to Methanosarcinales showed higher transcriptional activities in the thawed permafrost, indicating a shift of methanogens from hydrogenotrophic to partly acetoclastic methane-generating metabolic processes. In addition, data also show the soil texture and features change as a result of microbial reproduction and activity induced by this permafrost thaw. Those data indicate that microbial ecology under warming permafrost has potential impacts on ecosystem and methane emissions.

  13. A comparison between modelling for spatial distribution of thaw depths using MODIS datasets and observational data of permafrost in Mongolia

    Science.gov (United States)

    Zorigt, Munkhtsetseg; Alexander, Orkhonselenge; Kwadijk, Jaap; van Beek, Eelco

    2016-04-01

    Thaw and freezing depth and the related variation in the top of the active layer of the permafrost are important variables for studying runoff production in permafrost regions. In this study we provide data on spatially distributed thawing depths in Mongolia based on Kudryavtsev approach. This approach requires land surface temperature (LSTs) and soil physical characteristics for estimating thaw depths. Measured data of ground land surface temperatures is lacking in Mongolia. Therefore, we estimated the LST based on satellite images of surface temperatures. Monthly values of the LSTs were obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) data. Soil physical characteristics are defined by reference values from previous studies (Tumurbaatar, 2004; Anarmaa, 2006). We validated the results by comparing them with the observational data of permafrost boreholes in Mongolia in 2002-2009 CALM, 2009. The results indicate that thaw depths range between 0-14.5 m from southern to northern parts of Mongolia. This study shows that distribution of thaw depths using the MODIS LSTs can indicate a general overview of thaw depths distribution throughout the country.

  14. Experimental Study and Numerical Simulation of Seismic Behavior for RC Columns Subjected to Freeze-Thaw Cycles

    Directory of Open Access Journals (Sweden)

    Qing Qin

    2017-01-01

    Full Text Available Freeze-thaw of concrete is significantly responsible for serious damage to RC buildings, which may result in premature failure with little warning. Therefore, it is necessary to consider the effects of freeze-thaw environment when assessing seismic performance for RC structures. In this study, pseudo-static experiments of four RC columns were conducted in terms of different number of freeze-thaw cycles (FTCs. The results showed that the FTCs had an influence on the bearing capacity, ductility, strength, and stiffness of RC columns. What is more, the simulation results were commonly smaller than the experimental ones when simply assuming that the degrees of freeze-thaw damage for RC components were uniform. Thus, a numerical model considering uneven distribution of freeze-thaw damage was proposed by utilizing the results of Petersen’s test for relative dynamic modulus of elasticity (RDME for different depths of concrete sample and based on Berto’s method which was proved to be effective to convert the numbers of FTCs under different freeze-thaw conditions. On the basis of the existing constitutive relations for concrete, four RC columns subjected to different numbers of FTCs were simulated by OpenSees. As a result, the simulation hysteretic curves were in good agreement with the experimental ones.

  15. 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 (Carbon lost via CH4 efflux during the growing season at these intermediate age sites was 8% of uptake by net ecosystem exchange. Our results provide evidence that CH4 emissions following lowland 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.

  16. Effects of Different Levels of Pigeon Egg Yolk in Extenders on the Post-Thaw Semen Quality of Sahiwal Bulls

    Directory of Open Access Journals (Sweden)

    Hafez Jamil-ur-Rahman, Nazir Ahmad*, Najib-ur-Rahman, Salman Waheed, Maqbool Ahmad, Muhammad Younis1 and Tanveer Ahmad2

    2012-06-01

    Full Text Available In this study, effects of replacing chicken egg yolk (CEY with pigeon egg yolk (PEY in extenders on post-thaw semen quality in Sahiwal bulls were investigated. Attempts were also made to see if post thaw semen quality was affected by reducing PEY level in the extender. Twenty four semen samples were diluted with five Tris-based extenders. Extender A contained 20% CEY and was used as control, while extenders B, C, D and E contained 5, 10, 15 and 20% PEY, respectively. After freezing and storage for 24 hrs in liquid nitrogen, these samples were evaluated for post-thaw semen quality parameters.The difference in post extension sperm motility between extenders A (20% CEY and E (20% PEY was non significant. Post extension sperm motility decreased as the level of PEY in the extender was decreased. A similar trend was recorded for post thaw sperm motility, livability, absolute index of livability and sperm with intact plasma membrane. The percentages of spermatozoa with abnormal head, or tail were lower (P<0.01 in control extender A and extender E compared to extenders B, C and D. However, for abnormal mid-piece, extenders A and E showed lower values than extender C only. It was concluded that replacing CEY with PEY in same concentration (20% did not improve post thaw semen quality. Moreover, reducing the concentration of PEY in semen extender from 20 to 5% had adverse effects on post-thaw quality of Sahiwal bull semen.

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

    International Nuclear Information System (INIS)

    Chang, Eric Y.; Bae, Won C.; Statum, Sheronda; Du, Jiang; Chung, Christine B.

    2014-01-01

    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

  18. 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.

  19. Soil nutrient processes during spring thaw along a thermokarst recovery chronosequence

    Science.gov (United States)

    Buckeridge, K. M.; Schaeffer, S. M.; Baron, A.; Mack, M. C.; Schuur, E. A.; Schimel, J.

    2012-12-01

    Arctic soils store large pools of carbon (C) that are sensitive to a warming climate. When upland permafrost thaws, soil organic matter, C and nutrients are mobilized by the resulting landscape erosion. The intermediate ecosystem recovery stage (~ 50 y) is characterized by strongly enhanced above-ground biomass (shrubbiness) relative to undisturbed, early or late successional stages. However, upland arctic terrestrial ecosystems are very strongly nutrient- limited to plant growth and microbial activity, so the source of nutrients for this intermediate recovery stage is unknown. We hypothesized that nutrient inputs from upslope during spring thaw, combined with differential retention between recovery stages could be a potential mechanism. Furthermore, we hypothesized that the leachate nutrients from upslope vegetation would be an important stimulant to soil microbial activity at thaw. In winter, we placed ion exchange resin bags at the base of the snowpack, along the top, middle and base of each recovery stage slope. These were collected in spring and analyzed to estimate relative C, N and P inputs and outputs for each recovery stage. Also in winter, we collected snow cores (n=5) from the surface horizon of each of the recovery stages of the thermokarst chronosequence, in addition to live (dormant) plants and surface litter from snow-covered, undisturbed tundra directly above the thermokarst, with which we made cold (0-2 oC) vegetation leachate. To test the response of soil microbes to thaw pulses of vegetation leachate, we added this leachate (or water) to the frozen soil cores, and stepped them up in temperature from -10 oC to +4 oC over the course of 6 days and measured changes in microbial biomass and extractable soil biogeochemistry at the end of the incubation. As an indicator of soil microbial activity, we measured soil respiration and gross N mineralization over the course of the incubation. Time since thermokarst disturbance was the most important predictor

  20. 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

  1. Watershed water circle dynamics during long term farmland conversion in freeze-thawing area

    Science.gov (United States)

    Ouyang, Wei; Bing, Liu; Huang, Haobo; Hao, Fanghua; Hao, Zengchao

    2015-04-01

    Water resource is increasingly scarce in agricultural watershed under the pressure of socio-economic development. Long term land use conversion and freeze-thawing process posed additional characteristics to the water cycle. The semi-distributed hydrologic model Soil and Water Assessment Tool (SWAT) was employed for surface runoff, evaporation, and percolation simulations in freeze-thawing agricultural watershed. The interpreted five terms of land use data over three decades demonstrated that the percentage of the farmland area of the whole watershed increased from 23.5% to 62.1% and about half of dryland shifted to the paddy land in the recent ten years. The validated SWAT simulation showed that the spatial distribution of the surface runoff volume and the watershed averaged value increased 60 mm. The correlations of precipitation with surface runoff at monthly and yearly scales decreased from 0.8-0.9 to 0.6-0.7 respectively, which highlighted the impact of land use change over the surface runoff. The watershed evaporation was lower under the freeze-thawing condition, which increased from 363.7 mm to 418.5 mm over three decades. The field monitoring recorded the decreasing groundwater level, which was coincided with the expanding area of the paddy land. The watershed precipitation did not varied intensively in the whole simulation period (CV ⩽ 0.01), but the percolation varied as the result of the cultivation disturbance on soil properties. The analysis showed that the expanding paddy land decreased the groundwater level at 0.17 m/yr during 1997 and 2012, which posed new challenge on regional water management. The evapotranspiration in the extreme size of paddy land was relatively small and the groundwater level also decreased relatively slow. These characteristics demonstrated the impact of freeze-thawing on the water cycle. The proposed method can be used as an effective tool for quantitative prediction of irrigation water amount and identify the impact of land

  2. A prediction model for uniaxial compressive strength of deteriorated pyroclastic rocks due to freeze-thaw cycle

    Science.gov (United States)

    İnce, İsmail; Fener, Mustafa

    2016-08-01

    Either directly or indirectly, building stone is exposed to diverse atmospheric interactions depending on the seasonal conditions. Due to those interactions, objects of historic and cultural heritage, as well as modern buildings, partially or completely deteriorate. Among processes involved in rock deterioration, the freeze-thaw (F-T) cycle is one of the most important. Even though pyroclastic rocks have been used as building stone worldwide due to their easy workability, they are the building stone most affected by the F-T cycle. A historical region in Central Anatolia, Turkey, Cappadoia encompasses exceptional natural wonders characterized by fairy chimneys and unique historical and cultural heritage. Human-created caves, places of worship and houses have been dug into the pyroclastic rocks, which have in turn been used in architectural construction as building stone. Using 10 pyroclastic rock samples collected from Cappadocia, we determined the rock's index-mechanical properties to develop a statistical model for estimating percentage loss of uniaxial compressive strength a critical parameter of F-T cycle's important value. We used dry density (ρd), ultrasonic velocity (Vp), point load strengths (IS(50)), and slake-durability test indexes (Id4) values of unweathered rocks in our model, which is highly reliable (R2 = 0.84) for predetermination of percentage loss of uniaxial compressive strengths of pyroclastic rocks without requiring any F-T tests.

  3. Evaluation of an In Vitro of Human Immune Activation Induced by Freeze-Thaw Tissue Damage

    National Research Council Canada - National Science Library

    DuBose, D

    2002-01-01

    In training and in combat, soldiers are under the constant threat of injury. Injury that results in tissue necrosis can activate the immune system and ultimately enhance disturbances in organ function...

  4. Arctic Solutions The Frozen (Thawing) Relations of the High North

    International Nuclear Information System (INIS)

    Summers, Ch.

    2010-01-01

    It's cold, inhospitable and deadly. The image of the Arctic in years past is one of bewilderment, ignorance and awe. How the image of the Arctic has changed in recent years can be directly linked to our recognition that the Arctic has a great deal to offer in meeting the basic needs of future generations. Although we are still in awe of the Arctic's cruel beauty, new technologies are making it easier to explore the once unmanageable environment. The Arctic has moved into the mainstream with a host of suitors jockeying for position in the race to possess the Arctic and all that it contains. To highlight this increased interest, Russia's 'National Security Until 2020' initiative, has upgraded the High North to one of Russia's main priorities and identifies the Arctic as liable to produce military conflict in the future linked to competition for the Arctic's abundant raw materials.1 Even Canada, a peaceful and respectful country, has stepped outside the box of traditional Canadian rhetoric by giving Canada's Northern Strategy a tag line: 'Our North, our heritage, our future'. The Arctic is increasingly viewed as central to meeting the challenges of an ever changing world where climate change and economic benefit drive international agreements and policies. However Canada and Russia are not the only actors here. The other Arctic Five states: Denmark, Norway, and the United States of America all lay claims to some area or activity within the Arctic region. The Arctic is a unique part of this world, one that has been left largely untouched by human hands, and one that is on the brink of being changed forever. To fully understand Arctic issues, resource figures must be taken into account. Every nation involved in the Arctic debate has considered and based its policies on its set of numbers and resource estimates. A U.S. Geological Survey (USGS) in 2009 put Arctic resource figures in the range of thirty percent of the remaining world reserves of natural gas and ten percent

  5. Arctic Solutions The Frozen (Thawing) Relations of the High North

    Energy Technology Data Exchange (ETDEWEB)

    Summers, Ch.

    2010-07-01

    It's cold, inhospitable and deadly. The image of the Arctic in years past is one of bewilderment, ignorance and awe. How the image of the Arctic has changed in recent years can be directly linked to our recognition that the Arctic has a great deal to offer in meeting the basic needs of future generations. Although we are still in awe of the Arctic's cruel beauty, new technologies are making it easier to explore the once unmanageable environment. The Arctic has moved into the mainstream with a host of suitors jockeying for position in the race to possess the Arctic and all that it contains. To highlight this increased interest, Russia's 'National Security Until 2020' initiative, has upgraded the High North to one of Russia's main priorities and identifies the Arctic as liable to produce military conflict in the future linked to competition for the Arctic's abundant raw materials.1 Even Canada, a peaceful and respectful country, has stepped outside the box of traditional Canadian rhetoric by giving Canada's Northern Strategy a tag line: 'Our North, our heritage, our future'. The Arctic is increasingly viewed as central to meeting the challenges of an ever changing world where climate change and economic benefit drive international agreements and policies. However Canada and Russia are not the only actors here. The other Arctic Five states: Denmark, Norway, and the United States of America all lay claims to some area or activity within the Arctic region. The Arctic is a unique part of this world, one that has been left largely untouched by human hands, and one that is on the brink of being changed forever. To fully understand Arctic issues, resource figures must be taken into account. Every nation involved in the Arctic debate has considered and based its policies on its set of numbers and resource estimates. A U.S. Geological Survey (USGS) in 2009 put Arctic resource figures in the range of thirty percent of the

  6. Stability of coagulation factors in thawed, solvent/detergent-treated plasma during storage at 4 degrees C for 6 days.

    Science.gov (United States)

    Buchta, C; Felfernig, M; Höcker, P; Macher, M; Körmöczi, G F; Quehenberger, P; Heinzl, H; Knöbl, P

    2004-10-01

    Transfusion of fresh-frozen plasma is still a pillar in emergency medicine for using to prevent dilutional coagulopathy or disseminated intravascular coagulation after severe blood loss, but thawing procedures can delay its availability. On the other hand, the wastage of plasma, once thawed and not transfused within a defined time-period, represents an inefficient handling of economic resources and is contradictory to blood donor intentions. In this study we investigated the stability of coagulation factor activities and plasma protein levels during 6 days of storage of thawed solvent/detergent (S/D)-treated plasma at +4 degrees C. Our results may form the basis for reconsideration of expiry times of thawed S/D-treated plasma. Five units of S/D-treated plasma (Octaplas) were thawed and warmed to 20 degrees C, then recooled and stored at +4 degrees C for 6 days. The activities of coagulation factors II, V, VII, VIII, IX, X, XI and XII, fibrinogen, antithrombin (AT), protein C, protein S and von Willebrand factor antigen (vWF:Ag) were measured on days 0, 1, 2, 3 and 6. Except for protein S, the activities of all coagulation factors and inhibitors were at least 0.5 U/ml during storage at 4 degrees C for 6 days. The mean levels, during storage, of factors IX, X, XI and XII, vWF:Ag, fibrinogen and protein C were at least 94%, and of factors II, V and VIII, and AT at least 78%, of the levels immediately after thawing; the activity of factor VII decreased to 83% and of protein S to 43% of the baseline values. Thawed S/D-treated plasma stored at +4 degrees C for up to 6 days still contains sufficient coagulation activities and plasma proteins to be regarded as suitable for transfusion in the established indications.

  7. Assessment of motion and kinematic characteristics of frozen-thawed Sirohi goat semen using computer-assisted semen analysis.

    Science.gov (United States)

    Anand, Mukul; Yadav, Sarvajeet

    2016-02-01

    The aim was to determine the motion and kinematics characteristic of frozen-thawed spermatozoa in Sirohi goat using computer-assisted semen analysis. A study was carried out in Sirohi buck. Semen collection was made biweekly from each buck with the help of artificial vagina. A total of 12 ejaculates were collected from two bucks (six ejaculates from each buck). Freshly collected semen was pooled and later evaluated. The pooled semen sample was extended with standard glycerolated egg yolk tris extender and later subjected to a process of cryopreservation. The motion and kinematic characteristics of spermatozoa were studied during freez-thawing process. Significantly (plive percent, hypo-osmotic swelling test, and acrosomal integrity were recorded in neat semen followed by diluted and frozen thaw semen. The proportion of spermatozoa showing slow progression were the highest in the neat and diluted semen followed by rapid and non-progressively motile, while a reverse pattern was observed in the frozen thaw semen where the proportion of non-progressively motile spermatozoa were significantly (pvitality, plasma membrane integrity, and acrosome status were obtained in the neat semen followed by diluted and frozen thaw semen. Further, the process of cryopreservation results in a shift of motility from slow to non-progressive in the post-thaw semen with a significant decrease in the path velocities when compared to neat and diluted semen. Hence, it can be concluded that freezing-thawing process reduces the motility and kinematic characters spermatozoa and may be an important factor affecting the fertilizing ability of spermatozoa resulting in poor conception rate after insemination in goats.

  8. Assessment of motion and kinematic characteristics of frozen-thawed Sirohi goat semen using computer-assisted semen analysis

    Directory of Open Access Journals (Sweden)

    Mukul Anand

    2016-02-01

    Full Text Available Aim: The aim was to determine the motion and kinematics characteristic of frozen-thawed spermatozoa in Sirohi goat using computer-assisted semen analysis. Materials and Methods: A study was carried out in Sirohi buck. Semen collection was made biweekly from each buck with the help of artificial vagina. A total of 12 ejaculates were collected from two bucks (six ejaculates from each buck. Freshly collected semen was pooled and later evaluated. The pooled semen sample was extended with standard glycerolated egg yolk tris extender and later subjected to a process of cryopreservation. The motion and kinematic characteristics of spermatozoa were studied during freez-thawing process. Results: Significantly (p<0.01 higher value of live percent, hypo-osmotic swelling test, and acrosomal integrity were recorded in neat semen followed by diluted and frozen thaw semen. The proportion of spermatozoa showing slow progression were the highest in the neat and diluted semen followed by rapid and non-progressively motile, while a reverse pattern was observed in the frozen thaw semen where the proportion of non-progressively motile spermatozoa were significantly (p<0.01 higher followed by slow and rapid progression. Conclusion: This study showed that the best results for motion, vitality, plasma membrane integrity, and acrosome status were obtained in the neat semen followed by diluted and frozen thaw semen. Further, the process of cryopreservation results in a shift of motility from slow to non-progressive in the post-thaw semen with a significant decrease in the path velocities when compared to neat and diluted semen. Hence, it can be concluded that freezing-thawing process reduces the motility and kinematic characters spermatozoa and may be an important factor affecting the fertilizing ability of spermatozoa resulting in poor conception rate after insemination in goats.

  9. Effect of exogenous carbon addition and the freeze-thaw cycle on soil microbes and mineral nitrogen pools1

    Science.gov (United States)

    Hu, Xia; Yin, Peng; Nong, Xiang; Liao, Jinhua

    2018-01-01

    To elucidate the alpine soil process in winter, the response mechanism of soil mineral nitrogen and soil microbes to exogenous carbon (0 mg C, 1 mg C, 2 mg C, 4 mg C and 8 mg C·g-1 dry soil) and the freeze-thaw cycle (-2 °C, -2 ∼ 2 °C, -20 ∼2°C) were studied by laboratory simulation. The freeze-thaw treatment had no significant effect on microbial biomass nitrogen and the number of bacteria. The soil mineral N pool, the number of fungi, and enzyme activities were obviously affected by the freeze-thaw cycle. A mild freeze-thaw cycle (-2∼2°C) significantly increased the number of fungi and catalase activity, while severe freeze-thaw cycle (-20∼2°C) obviously decreased invertase activity. The results suggested that both the freeze-thaw rate and freeze-thaw temperature amplitudes have a strong effect on soil microbial dynamics in the alpine zone in winter. The results showed that exogenous carbon addition significantly decreased soil NO3-N and NH4 +-N contents, increased soil microbial biomass, the number of microbes, and soil enzyme activities. The results showed that microbial growth in the eastern Tibetan Plateau was somewhat limited by available C. It may represent a larger potential pulse of soil nutrient for alpine plants in the next spring, and may be instrumental for plant community shifts under future climate change predictions due to the possible increased litter addition.

  10. Assessment of motion and kinematic characteristics of frozen-thawed Sirohi goat semen using computer-assisted semen analysis

    Science.gov (United States)

    Anand, Mukul; Yadav, Sarvajeet

    2016-01-01

    Aim: The aim was to determine the motion and kinematics characteristic of frozen-thawed spermatozoa in Sirohi goat using computer-assisted semen analysis. Materials and Methods: A study was carried out in Sirohi buck. Semen collection was made biweekly from each buck with the help of artificial vagina. A total of 12 ejaculates were collected from two bucks (six ejaculates from each buck). Freshly collected semen was pooled and later evaluated. The pooled semen sample was extended with standard glycerolated egg yolk tris extender and later subjected to a process of cryopreservation. The motion and kinematic characteristics of spermatozoa were studied during freez-thawing process. Results: Significantly (p<0.01) higher value of live percent, hypo-osmotic swelling test, and acrosomal integrity were recorded in neat semen followed by diluted and frozen thaw semen. The proportion of spermatozoa showing slow progression were the highest in the neat and diluted semen followed by rapid and non-progressively motile, while a reverse pattern was observed in the frozen thaw semen where the proportion of non-progressively motile spermatozoa were significantly (p<0.01) higher followed by slow and rapid progression. Conclusion: This study showed that the best results for motion, vitality, plasma membrane integrity, and acrosome status were obtained in the neat semen followed by diluted and frozen thaw semen. Further, the process of cryopreservation results in a shift of motility from slow to non-progressive in the post-thaw semen with a significant decrease in the path velocities when compared to neat and diluted semen. Hence, it can be concluded that freezing-thawing process reduces the motility and kinematic characters spermatozoa and may be an important factor affecting the fertilizing ability of spermatozoa resulting in poor conception rate after insemination in goats. PMID:27051209

  11. Effect of permafrost thaw on CO2 and CH4 exchange in a western Alaska peatland chronosequence

    International Nuclear Information System (INIS)

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

    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 (CH 4 ), a potent greenhouse gas. To examine the effects of lowland permafrost thaw over millennial timescales, we measured carbon dioxide (CO 2 ) and CH 4 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 CH 4 exchange in July (123 ± 71 mg CH 4 –C m −2 d −1 ) was observed in features that have been thawed for 30 to 70 (<100) yr, where soils were warmer than at more recently thawed sites (14 to 21 yr; emitting 1.37 ± 0.67 mg CH 4 –C m −2 d −1 in July) and had shallower water tables than at older sites (200 to 1400 yr; emitting 6.55 ± 2.23 mg CH 4 –C m −2 d −1 in July). Carbon lost via CH 4 efflux during the growing season at these intermediate age sites was 8% of uptake by net ecosystem exchange. Our results provide evidence that CH 4 emissions following lowland permafrost thaw are enhanced over decadal time scales, but limited over millennia. Over larger spatial scales, adjacent fen systems may contribute sustained CH 4 emission, CO 2 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 CH 4 emission to the atmosphere that must be considered for a complete understanding of high latitude CH 4 dynamics. (paper)

  12. 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.

  13. Increased susceptibility to repeated freeze-thaw cycles in Escherichia coli following long-term evolution in a benign environment

    Directory of Open Access Journals (Sweden)

    Lenski Richard E

    2006-12-01

    Full Text Available Abstract Background In order to study the dynamics of evolutionary change, 12 populations of E. coli B were serially propagated for 20,000 generations in minimal glucose medium at constant 37°C. Correlated changes in various other traits have been previously associated with the improvement in competitive fitness in the selective environment. This study examines whether these evolved lines changed in their ability to tolerate the stresses of prolonged freezing and repeated freeze-thaw cycles during adaptation to a benign environment. Results All 12 lines that evolved in the benign environment for 20,000 generations are more sensitive to freeze-thaw cycles than their ancestor. The evolved lines have an average mortality rate of 54% per daily cycle, compared to the ancestral rate of 34%. By contrast, there was no significant difference between the evolved lines and their ancestor in mortality during prolonged freezing. There was also some variability among the evolved lines in susceptibility to repeated freeze-thaw cycles. Those lines that had evolved higher competitive fitness in the minimal glucose medium at 37°C also had higher mortality during freeze-thaw cycles. This variability was not associated, however, with differences among lines in DNA repair functionality and mutability. Conclusion The consistency of the evolutionary declines in freeze-thaw tolerance, the correlation between fitness in glucose medium at 37°C and mortality during freeze-thaw cycles, and the absence of greater declines in freeze-thaw survival among the hypermutable lines all indicate a trade-off between performance in minimal glucose medium at 37°C and the capacity to tolerate this stress. Analyses of the mutations that enhance fitness at 37°C may shed light on the physiological basis of this trade-off.

  14. 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

  15. Effect of permafrost thaw on carbon fluxes, litter decomposition and ecohydrology in a sub-arctic peatland: increased uncertainty from transitional dynamics

    Science.gov (United States)

    Malhotra, A.; Roulet, N. T.; Moore, T. R.; Limpens, J.

    2016-12-01

    Carbon (C) release from thawing permafrost in ice-rich peatlands is spatially and temporally heterogeneous due to abrupt localized changes following initial thaw. We investigated the contribution of transitional thaw areas to variability in C loss by evaluating changes in moisture regimes, vegetation, litter decomposition and C fluxes. In a thaw chronosequence at Stordalen mire in northern Sweden, we found that adjacent thawed and unthawed areas had unrelated water table fluctuations. These abrupt hydrological changes were associated with a weakened link between water table depth and above-ground plant abundance, and with non-linear shifts in the partitioning of gaseous effluxes between CO2 and CH4. Inclusion of soil temperature along with ecohydrological variability improved predictions of non-linear changes in C flux after permafrost thaw. Structural heterogeneity across the thaw gradient also decreased the predictability of litter decomposition rates by its key theoretical controls (moisture and temperature). Instead, litter decomposition was well predicted by surface elevation. We will present the key mechanisms by which transitional thaw stages increase landscape scale C flux uncertainty and provide suggestions for modeling and upscaling C loss from thawing ice-rich peatlands.

  16. Follicular size predicts success in artificial insemination with frozen-thawed sperm in donkeys.

    Science.gov (United States)

    Saragusty, Joseph; Lemma, Alemayehu; Hildebrandt, Thomas Bernd; Göritz, Frank

    2017-01-01

    In asses, semen collection, cryopreservation, and artificial insemination (AI) with frozen-thawed semen have been scarcely described and success rate, particularly following AI, is reportedly low. In the absence of reliable protocols, assisted reproductive technologies cannot support the conservation efforts aimed at endangered wild ass species and domestic donkey breeds. Two experiments were conducted in this study. In experiment 1 we evaluated freezing Abyssinian donkey (N = 5, 4 ejaculates each) spermatozoa using three freezing extenders (Berliner Cryomedium + glycerol, BC+G; BotuCrio, BOTU; INRAFreeze, INRA) and two cryopreservation techniques (liquid nitrogen vapour, LNV; directional freezing, DF). Post-thaw evaluation indicated that BOTU and INRA were similar and both superior to BC+G (P ≤ 0.004 for all motility tests), and that DF was superior to LNV (P < 0.002 for all evaluation parameters). In experiment 2, relying on these results, we used Abyssinian donkey sperm frozen in BOTU and INRA by DF for AI (N = 20). Prior to AI, thawed samples were diluted in corresponding centrifugation media or autologous seminal fluids at 1:1 ratio. No difference was found between BOTU and INRA or between the addition of seminal fluids or media, all resulting in ~50% pregnancy, and no differences were noted between males (N = 4). The size of pre-ovulatory follicle was a significant (P = 0.001) predictor for AI success with 9/10 pregnancies occurring when follicular size ranged between 33.1-37.4 mm, no pregnancy when it was smaller, and only one when larger. A number of ass species face the risk of extinction. Knowledge gained in this study on the Abyssinian donkey can be customised and transferred to its closely related endangered species and breeds.

  17. Rapid detection of frozen pork quality without thawing by Vis-NIR hyperspectral imaging technique.

    Science.gov (United States)

    Xie, Anguo; Sun, Da-Wen; Xu, Zhongyue; Zhu, Zhiwei

    2015-07-01

    Quality determination of frozen food is a time-consuming and laborious work as it normally takes a long time to thaw the frozen samples before measurements can be carried out. In this research, a rapid and non-destructive determination technique for frozen pork quality was tested with a hyperspectral imaging (HSI) system. In this study, 120 pieces of pork meat were frozen by four kinds of methods with various freezing temperatures from -20 to -120°C. The hyperspectral images of the samples were acquired at the frozen state. Quality indicators including drip loss, pH value, color, cooking loss and Warner-Bratzler shear force (WBSF) of the samples were measured after thawing. The spectral characteristics of the frozen meat samples were studied and it was revealed that the reflectance at 1100nm had a close relationship with the freezing temperature (R=-0.832, p<0.01). Partial least squares regression (PLSR) was applied to establish the spectral models, and the models were then optimized. Results showed that the improved region of interest (ROI) method could be used to extract effective spectral information to withstand the interference of freezing, and choosing appropriate spectral bands and spectral pretreatment techniques were crucial to develop robust mathematical model. The performances of the models established were diverse based on different quality indicators. The coefficients of determination for prediction (Rp(2)) for L*, cooking loss, b*, drip loss and a* were 0.907, 0.845, 0.814, 0.762, and 0.716, respectively. However there were low correlations (Rp(2)) for pH and WBSF measurements. The current study indicated that HSI had the potential for non-destructive determination of frozen meat quality without thawing. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. 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].

  19. Effects of dithioerythritol on ram semen after the freeze-thawing process.

    Science.gov (United States)

    Başpınar, Nuri; Coyan, Kenan; Bucak, Mustafa Numan; Tuncer, Pürhan Barbaros

    2011-12-01

    The aim of this study was to evaluate the effects of dithioerythritol added to cryopreservation extender on the post-thawed sperm parameters, lipid peroxidation and antioxidant activities of Merino ram sperm. Semen samples from 5 mature Merino rams (1 and 2 years of age) were used in the study. Semen samples, which were diluted with a Tris-based extender containing 0.5, 1, and 2mM dithiothreitol and no antioxidant (control), were cooled to 5°C and frozen in 0.25 ml French straws. Frozen straws were then thawed individually at 37°C for 20s in a water bath for evaluation. The addition of dithioerythritol at 0.5 and 2mM doses led to higher percentages of subjective motility (62.9±4.2% and 63.6±1.8%) compared to control (52.0±4.9%, Pcontrol (44.2±8.7%, Pcontrol (15.0±2.5%). Dithioerythritol at 1 and 2 mM doses for ALH provided higher values compared to the control (Pprocess. Supplementation with dithiothreitol did not significantly affect the integrities of sperm membrane and acrosome, and mitochondrial activities. No significant differences were observed in biochemical parameters among the groups (P>0.05). Findings of this study showed that dithioerythritol supplementation in semen extenders, was of greater benefit to sperm motility of frozen-thawed ram sperm. Copyright © 2011 Elsevier Inc. All rights reserved.

  20. Chicks produced in the Magellanic penguin (Spheniscus magellanicus) after cloacal insemination of frozen-thawed semen.

    Science.gov (United States)

    O'Brien, Justine Kellie; Steinman, Karen J; Montano, Gisele A; Dubach, Jean M; Robeck, Todd R

    2016-07-01

    The in vitro and in vivo functionality of cryopreserved spermatozoa was examined over two breeding seasons in a zoological colony of Magellanic penguins (Spheniscus magellanicus). Frozen-thawed semen was inseminated into five anesthetized females, over a total of eight egg production cycles, with a different male used for each artificial insemination (AI) within each season. Females were maintained within the colony in cordoned nest sites to prevent copulation with their paired male, and were inseminated every 3-10 days until the first oviposition. Semen frozen from seven males using a straw method retained 39.8%, 25.7%, 74.0%, and 52.1% of its initial total motility, progressive motility, average path velocity, and plasma membrane integrity, respectively. Normal morphology of motile cells was reduced (P inseminations before the first oviposition, with 19.2 ± 1.6 × 10(6) motile, morphologically normal spermatozoa per insemination. Overall fertility was 53.3% (8/15 eggs), hatchability was 50.0% (4/8), and genetic analyses confirmed that all embryos and hatchlings were sired by the AI male. Fertile eggs were laid at 4.0-12.1 days after AI, indicating that frozen-thawed spermatozoa resided in the female reproductive tract for up to ∼7.2 days prior to fertilization. Results demonstrate that frozen-thawed Magellanic penguin spermatozoa are fully functional in vivo and support the use of genome banking and AI as tools for managing the sustainability of zoological penguin populations. Zoo Biol. 35:326-338, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  1. 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.

  2. 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.

  3. Circumpolar freeze/thaw surface status and surface soil moisture from Metop ASCAT

    Science.gov (United States)

    Bartsch, Annett; Paulik, Christoph; Melzer, Thomas; Hahn, Sebastian; Wagner, Wolfgang

    2013-04-01

    Circumpolar surface soil moisture and freeze/thaw surface status has been derived from Metop ASCAT within the framework of the ESA DUE Permafrost and STSE ALANIS-Methane projects. The dataset is available via Pangaea (doi:10.1594/PANGAEA.775959) and can be vizualized with the WebGIS of the DUE Permafrost data portal (www.ipf.tuwien.ac.at/permafrost). MetOp ASCAT data have been used for both the near surface soil moisture (SSM) product and determination of freeze/thaw status at panboreal/ arctic scale. Metop-A, launched in October 2006 by the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT), is the first of three satellites within EUMETSAT's Polar System (EPS). The ASCAT SSM DUE Permafrost product is the result of an improved SSM retrieval algorithm developed at the Institute for Photogrammetry and Remote Sensing (IPF) of the Vienna University of Technology. The SSM Product is delivered with a weekly temporal resolution and 25 km spatial resolution. The soil moisture product also includes a quality flag which contains the number of used measurements. Data are masked for frozen ground conditions also based on MetOp ASCAT. The daily SSF is available as separate flag. The SSM product is provided as weekly averaged images north of 50°N in GeoTIFF/NetCDF format and EASE Grid projection Further, complementary regional scale (1km) freeze/thaw information is available at selected sites based on ENVISAT ASAR GM (PANGAEA http://doi.pangaea.de/10.1594/PANGAEA.779658).

  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. Four years of UAS Imagery Reveals Vegetation Change Due to Permafrost Thaw

    Science.gov (United States)

    DelGreco, J. L.; Herrick, C.; Varner, R. K.; McArthur, K. J.; McCalley, C. K.; Garnello, A.; Finnell, D.; Anderson, S. M.; Crill, P. M.; Palace, M. W.

    2017-12-01

    Warming trends in sub-arctic regions have resulted in thawing of permafrost which in turn induces change in vegetation across peatlands. Collapse of palsas (i.e. permafrost plateaus) has also been correlated to increases in methane (CH4) emissions to the atmosphere. Vegetation change provides new microenvironments that promote CH4 production and emission, specifically through plant interactions and structure. By quantifying the changes in vegetation at the landscape scale, we will be able to understand the impact of thaw on CH4 emissions in these complex and climate sensitive northern ecosystems. We combine field-based measurements of vegetation composition and high resolution Unmanned Aerial Systems (UAS) imagery to characterize vegetation change in a sub-arctic mire. At Stordalen Mire (1 km x 0.5 km), Abisko, Sweden, we flew a fixed-wing UAS in July of each year between 2014 and 2017. High precision GPS ground control points were used to georeference the imagery. Seventy-five randomized square-meter plots were measured for vegetation composition and individually classified into one of five cover types, each representing a different stage of permafrost degradation. With this training data, each year of imagery was classified by cover type. The developed cover type maps were also used to estimate CH4 emissions across the mire based on average flux CH4 rates from each cover type obtained from flux chamber measurements collected at the mire. This four year comparison of vegetation cover and methane emissions has indicated a rapid response to permafrost thaw and changes in emissions. Estimation of vegetation cover types is vital in our understanding of the evolution of northern peatlands and its future role in the global carbon cycle.

  6. Sub-seasonal thaw slump mass wasting is not consistently energy limited at the landscape scale

    Science.gov (United States)

    Zwieback, Simon; Kokelj, Steven V.; Günther, Frank; Boike, Julia; Grosse, Guido; Hajnsek, Irena

    2018-02-01

    Predicting future thaw slump activity requires a sound understanding of the atmospheric drivers and geomorphic controls on mass wasting across a range of timescales. On sub-seasonal timescales, sparse measurements indicate that mass wasting at active slumps is often limited by the energy available for melting ground ice, but other factors such as rainfall or the formation of an insulating veneer may also be relevant. To study the sub-seasonal drivers, we derive topographic changes from single-pass radar interferometric data acquired by the TanDEM-X satellites. The estimated elevation changes at 12 m resolution complement the commonly observed planimetric retreat rates by providing information on volume losses. Their high vertical precision (around 30 cm), frequent observations (11 days) and large coverage (5000 km2) allow us to track mass wasting as drivers such as the available energy change during the summer of 2015 in two study regions. We find that thaw slumps in the Tuktoyaktuk coastlands, Canada, are not energy limited in June, as they undergo limited mass wasting (height loss of around 0 cm day-1) despite the ample available energy, suggesting the widespread presence of early season insulating snow or debris veneer. Later in summer, height losses generally increase (around 3 cm day-1), but they do so in distinct ways. For many slumps, mass wasting tracks the available energy, a temporal pattern that is also observed at coastal yedoma cliffs on the Bykovsky Peninsula, Russia. However, the other two common temporal trajectories are asynchronous with the available energy, as they track strong precipitation events or show a sudden speed-up in late August respectively. The observed temporal patterns are poorly related to slump characteristics like the headwall height. The contrasting temporal behaviour of nearby thaw slumps highlights the importance of complex local and temporally varying controls on mass wasting.

  7. Separation of motile spermatozoa from frozen-thawed buffalo semen: swim-up vs filtration procedures.

    Science.gov (United States)

    Mustafa, G; Anzar, M; Arslan, M

    1998-07-15

    Three experiments were conducted to maximize the recovery rate of motile spermatozoa from frozen-thawed buffalo semen. In Experiment 1, the swim-up of motile spermatozoa was performed in the presence or absence of HEPES in TALP medium and CO2 in the environment. The recovery rate of motile spermatozoa in TALP medium (control), TALP + HEPES + CO2, TALP + HEPES and TALP + CO2 was 15, 18, 12 and 10%, respectively (P > 0.05), with sperm motility at 87, 89, 90 and 90%, respectively (P > 0.05). In Experiment 2, the pH of TALP medium was adjusted to 7.0, 7.5, 8.0, 8.5 and 9.0, and swim-up procedure was performed in the presence of HEPES and CO2. The recovery rate of motile spermatozoa at different pH was 14, 20, 24, 27 and 16%, respectively (P 0.05). In Experiment 3, the efficiency of ion-exchange filtration and Swim-up procedure in separating motile spermatozoa from frozen-thawed buffalo semen was compared. The recovery rate of motile spermatozoa was 95% in filtration procedure and 33% in swim-up procedure (P 0.05). In conclusion, HEPES and CO2 had no significant effect on swim-up of buffalo spermatozoa. The pH 8.5 of TALP improved the recovery rate of motile spermatozoa in swim-up procedure. The ion-exchange filtration was found superior to swim-up procedure in harvesting maximum number of motile spermatozoa from frozen-thawed buffalo semen (95 vs 33%; P < 0.001).

  8. Digestion of frozen/thawed food waste in the hybrid anaerobic solid-liquid system

    International Nuclear Information System (INIS)

    Stabnikova, O.; Liu, X.Y.; Wang, J.Y.

    2008-01-01

    The hybrid anaerobic solid-liquid (HASL) system, which is a modified two-phase anaerobic digester, is to be used in an industrial scale operation to minimize disposal of food waste at incineration plants in Singapore. The aim of the present research was to evaluate freezing/thawing of food waste as a pre-treatment for its anaerobic digestion in the HASL system. The hydrolytic and fermentation processes in the acidogenic reactor were enhanced when food waste was frozen for 24 h at -20 deg. C and then thawed for 12 h at 25 deg. C (experiment) in comparison with fresh food waste (control). The highest dissolved COD concentrations in the leachate from the acidogenic reactors were 16.9 g/l on day 3 in the control and 18.9 g/l on day 1 in the experiment. The highest VFA concentrations in the leachate from the acidogenic reactors were 11.7 g/l on day 3 in the control and 17.0 g/l on day 1 in the experiment. The same volume of methane was produced during 12 days in the control and 7 days in the experiment. It gave the opportunity to diminish operational time of batch process by 42%. The effect of freezing/thawing of food waste as pre-treatment for its anaerobic digestion in the HASL system was comparable with that of thermal pre-treatment of food waste at 150 deg. C for 1 h. However, estimation of energy required either to heat the suspended food waste to 150 deg. C or to freeze the same quantity of food waste to -20 deg. C showed that freezing pre-treatment consumes about 3 times less energy than thermal pre-treatment

  9. Seepage erosion of Arctic coastal bluffs driven by thawing permafrost in Northwest Alaska

    Science.gov (United States)

    Phillips, C. B.; Jerolmack, D. J.; Crosby, B. T.

    2010-12-01

    On the forefront of transient landscapes is the Arctic. Air and sea surface temperatures have increased significantly in the last 50 years due to anthropogenic warming, and have been blamed for observed accelerations in coastal erosion rates and the formation of thermokarst features. The controls that permafrost exerts on landforms and sediment transport are largely unknown, but may be elucidated by examining landscape response to permafrost thaw. Using current and historical aerial photos of Northwest Alaska we identified an area of coastal bluffs experiencing increased erosion. What makes this portion of the coast unusual is that erosion is not driven by thermomechanical action from waves, however waves are important in the removal of material from the base of the slump. Instead, retrogressive slump failures - which have seen accelerated growth in the 1900s - initiated the growth of headward cutting alcoves that have now penetrated up to a hundred meters inland. Our field topographic surveys reveal that slumps decrease in slope and increase in circularity with increasing size, suggesting a temporal growth progression toward an asymptotic quasi-circular planform shape. Morphometric scaling relationships suggest that groundwater seepage erosion may be driving alcove growth. Junction angles of alcoves, and the trajectories of headcutting measured from repeat aerial photography, also support a model of ground water competition as the primary mechanism of continued growth. Coastal erosion rates do not depend on solar radiation flux; we propose therefore that seepage water is derived from a vertical lowering of the permafrost table, by thaw resulting from increased ambient air temperatures. Slump features such as those observed here are expected to become more numerous on Arctic coastal and river bluffs in the approaching decades as mean summer air temperatures continue to rise. Thawing of permafrost shows how the Arctic landscape is out of equilibrium, eroding as a

  10. 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

  11. The Contribution of Old Carbon to Respiration from Alaskan Tundra Following Permafrost Thaw

    Science.gov (United States)

    Schuur, E. A.; Vogel, J. G.; Crummer, K. G.; Lee, H.; Sickman, J. O.; Dutta, K.

    2007-12-01

    More than 450 Pg of soil carbon (C) has accumulated in high latitude ecosystems after the retreat of the last major ice sheets. Recent studies suggest that, due to climate warming, these ecosystems may no longer be accumulating C, and in some cases may be losing stored C to the atmosphere. We used radiocarbon measurements of carbon dioxide to detect the age of C respired from tussock tundra near Denali National Park, Alaska. At this tundra site, permafrost has been observed to warm and thaw over the past several decades, causing the ground surface to subside as ice volume in the soil decreased. We established three sites within this area that differed in vegetation and surface topography; both characteristics varied in relation to the degree of permafrost thaw. We made radiocarbon measurements of ecosystem respiration, incubations of soil organic matter, and incubations of above and belowground plant biomass to determine the age and isotopic value of C respired from these sites. Over the study period from 2004 to 2006, ecosystem respiration radiocarbon values averaged from +35‰ to +95‰ in different months across sites. For soil incubations, surface soil radiocarbon was elevated relative both to ecosystem respiration and the current atmospheric radiocarbon value, demonstrating the significant contribution from C fixed over the past years to several decades. The deeper soil, in contrast, had respiration isotope values that averaged below zero, reflecting the significant effect of radioactive decay on the isotope content of deeper soil layers. The plant and soil incubations were combined in a multi- source mixing model to determine probable contributions from these different sources to ecosystem respiration. Deep soil respiration generally averaged between 5-15% of total ecosystem respiration, but reached as high as 40% in some months. When aggregated across the growing season, the two sites undergoing more disturbance from permafrost thaw had on average 2-3 times

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

    Directory of Open Access Journals (Sweden)

    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

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

    DEFF Research Database (Denmark)

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

    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...... 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...

  15. Preservation of labile organic matter in soils of drained thaw lakes in Northern Alaska

    Science.gov (United States)

    Mueller, Carsten W.; Rethemeyer, Janet; Kao-Kniffin, Jenny; Löppmann, Sebastian; Hinkel, Kenneth; Bockheim, James

    2014-05-01

    A large number of studies predict changing organic matter (OM) dynamics in arctic soils due to global warming. In contrast to rather slowly altering bulk soil properties, single soil organic matter (SOM) fractions can provide a more detailed picture of the dynamics of differently preserved SOM pools in climate sensitive arctic regions. By the study of the chemical composition of such distinctive SOM fractions using nuclear magnetic resonance spectroscopy (NMR) together with radiocarbon analyses it is possible to evaluate the stability of the major OM pools. Approximately 50-75% of Alaska's Arctic Coastal Plain is covered with thaw lakes and drained thaw lakes that follow a 5,000 yr cycle of development (between creation and final drainage), thus forming a natural soil chronosequence. The drained thaw lakes offer the possibility to study SOM dynamics affected by permafrost processes over millennial timescales. In April 2010 we sampled 16 soil cores (including the active and permanent layer) reaching from young drained lakes (0-50 years since drainage) to ancient drained lakes (3000-5500 years since drainage). Air dried soil samples from soil horizons of the active and permanent layer were subjected to density fractionation in order to differentiate particulate OM and mineral associated OM. The chemical composition of the SOM fractions was analyzed by 13C CPMAS NMR spectroscopy. For a soil core of a young and an ancient drained thaw lake basin we also analyzed the 14C content. For the studied soils we can show that up to over 25 kg OC per square meter are stored mostly as labile, easily degradable organic matter rich in carbohydrates. In contrast only 10 kg OC per square meter were sequestered as presumably more stable mineral associated OC dominated by aliphatic compounds. Comparable to soils of temperate regions, we found small POM (dating we could show the stabilization of younger more labile OM at greater depth in buried O horizons. Additionally the study of the

  16. 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

  17. 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.

  18. 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.

  19. [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.

  20. Influence of waxy rice flour substitution for wheat flour on characteristics of batter and freeze-thawed cake.

    Science.gov (United States)

    Jongsutjarittam, Nisachon; Charoenrein, Sanguansri

    2013-09-12

    This study aimed to improve the freeze-thawed cake properties by10-20% waxy rice flour (WRF) substitution for wheat flour (WF). Viscosity of WRF-substituted batters was lower; consequently, trapped air was less uniformly distributed than WF batter. After five freeze-thaw cycles, firmness and enthalpy of melting retrograded amylopectin of WF- and WRF-substituted cakes increased and the matrix surrounding the air pores from SEM images was denser than in fresh-baked cakes. Sensory evaluation showed an increase in firmness and a decrease in firmness acceptability of freeze-thawed cakes. However, freeze-thawed cake with WRF substitution had significantly less firmness, less dense matrix and more acceptability than WF cake. This could have been due to a low amylose content of WRF and the spread of ruptured waxy rice starch granules around swollen wheat starch granules as observed by CLSM. Thus, WRF could be used for WF substitution to improve the firmness in freeze-thawed cake. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Effects of trehalose supplementation on cell viability and oxidative stress variables in frozen-thawed bovine calf testicular tissue.

    Science.gov (United States)

    Zhang, Xiao-Gang; Wang, Yan-Hua; Han, Cong; Hu, Shan; Wang, Li-Qiang; Hu, Jian-Hong

    2015-06-01

    Trehalose is widely used for cryopreservation of various cells and tissues. Until now, the effect of trehalose supplementation on cell viability and antioxidant enzyme activity in frozen-thawed bovine calf testicular tissue remains unexplored. The objective of the present study was to compare the effect of varying doses of trehalose in cryomedia on cell viability and key antioxidant enzymes activities in frozen-thawed bovine calf testicular tissue. Bovine calf testicular tissue samples were collected and cryopreserved in the cryomedias containing varying doses (0, 5, 10, 15, 20 and 25%; v/v) of trehalose, respectively. Cell viability, total antioxidant capacity (T-AOC) activity, catalase (CAT) activity, superoxide dismutase (SOD) activity, glutathione (GSH) content and malondialdehyde (MDA) content were measured and analyzed. The results showed that cell viability, T-AOC activity, SOD activity, CAT activity and GSH content of frozen-thawed bovine calf testicular tissue was decreased compared with that of fresh group (Pcell viability and antioxidant enzyme activity (SOD and CAT) among frozen-thawed groups (P0.05). In conclusion, the cryomedia added 15% trehalose reduced the oxidative stress and improved the cryoprotective effect of bovine calf testicular tissue. Further studies are required to obtain more concrete results on the determination of antioxidant capacity of trehalose in frozen-thawed bovine calf testicular tissue. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. 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.

  3. Effect of Addition of Concentrated Proteins and Seminal Plasma Low Molecular Weight Proteins in Freezing and Thawing of Equine Semen

    Directory of Open Access Journals (Sweden)

    Fagundes, B.

    2011-07-01

    Full Text Available Difficulties in obtaining equine frozen semen with potential fertility are recognized. This study was designed to investigate the effect of seminal plasma on frozen/thawing of eight stallion semen from different breed using the following treatments: Seminal plasma with ten-fold concentrated proteins with molecular weight above 10 kDa on frozen extender; Part of seminal plasma with proteins under 10 kDa on frozen extender; Conventional freezing, using whole seminal plasma on frozen extender. Using the parameter of 30% of seminal motility post-thawing as index of good freezability, it was verified an increased percentage of stallions that presented good freezability when semen was frozen with seminal plasma containing ten-fold concentrated proteins with molecular weight above 10 kDa on frozen extender. These results, suggested the use of seminal plasma concentrated proteins from own stallion to freezing/thawing semen.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  6. Ultrastructure of fresh and post thawed sperm of pejerrey Odontesthes bonariensis (Atheriniformes

    Directory of Open Access Journals (Sweden)

    Ángela Gárriz

    Full Text Available In the present study it was showed for the first time the ultrastructural morphology of O. bonariensis sperm using electron microscopy techniques. Different kinds of abnormalities were described in fresh and post thawed sperm caused by crogenic protocols. Pejerrey spermatozoon is uniflagellated and is differentiated into three parts: a small roundish head (~1.80µm in length and 1.67µm in width, a midpiece or transitional region (~1.11µm in length and 1.56µm in width, and a long tail or flagellum (~29.08µm. Samples of fresh and post thawed sperm showed evidence of morphological anomalies affecting various intracellular compartments. Spermatozoa with swollen, ruptured, or absent membranes in the head showing excess of cytoplasm, and with alteration of the spatial orientation of the mitochondria were observed. A swollen flagellum was observed containing cytoplasmic vesicles, distributed along the whole length or concentrated in a restricted part of the tail. It was also found a high level of abnormalities (60% in frozen sperm when compared with normal sperm (18% reflecting the damage provoked by cryopreservation procedures.

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

    Directory of Open Access Journals (Sweden)

    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.

  8. 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.

  9. 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%.

  10. 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. 

  11. 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.

  12. 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

  13. 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.

  14. The committed long-term sink of carbon due to vegetation changes may rival carbon losses due to permafrost thawing

    Science.gov (United States)

    Pugh, Thomas; Jones, Chris; Burton, Chantelle; Huntingford, Chris; Arneth, Almut; Lomas, Mark; Piao, Shilong; Sitch, Stephen

    2017-04-01

    The terrestrial biosphere provides an important sink of atmospheric carbon, the size and persistence of which is one of the largest uncertainties in future climate projections. However, the response of the biosphere to changes in its environment substantially lags the rate of environmental change in many aspects. Transient assessments of changes in ecosystem properties therefore do not capture the full magnitude of the response to which ecosystems are committed. Here an ensemble of Dynamic Global Vegetation Model and Earth System Model simulations is used to assess the magnitude of committed changes in tree cover and carbon storage, to attribute the drivers of uncertainty in these values, and to assess the likely magnitude and direction of committed changes in biospheric carbon stocks post 2100. The results show consistently large committed changes post-2100 in slow components of ecosystems, notably carbon stores and vegetation cover fractions, despite relatively small changes in productivity. In boreal locations, increases in vegetation and soil carbon storage may be large enough to offset committed carbon losses from thawing permafrost. As much of this committed sink results from increased biomass as a result of changes in vegetation composition, the results indicate a pressing need for vegetation dynamics, as well as the now widely-considered anthropogenic land cover change, to be more routinely represented in the coupled Earth System Models used to make future climate projections. However, the timescales over which committed changes in vegetation cover and biomass occur are highly uncertain, and represent a key limitation in assessing whether the simulated committed sink will be realised on human-relevant timescales. A move away from evaluating DGVMs in terms of their stable vegetation state, towards addressing their ability to capture transient responses, is advocated.

  15. Frost/thaw cycling resistance of back filling building materials for ground heat pipes; Frost-Tau-Wechselbestaendigkeit von Hinterfuellbaustoffen fuer Erdwaermesonden

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Lutz [Hochschule Ostwestfalen-Lippe, Fachgebiet Geotechnik, Hoexter (Germany)

    2009-07-15

    Backfilling materials for geothermal wells must meet certain specifications concerning groundwater protection, system efficiency, and long-term availability. Lately, the focus has shifted to the freezing and thawing resistance. The contribution presents a novel method of investigation which combines standard methods of measurement to assess the sealing properties and freeze/thaw cycle resistance of backfilling materials. (orig.)

  16. Investigation of the impact of nanotechnology on the freeze-thaw durability of concrete containing d-cracking aggregates : [technical summary].

    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 nan...

  17. A complete human pelvis from the Middle Pleistocene of Spain.

    Science.gov (United States)

    Arsuaga, J L; Lorenzo, C; Carretero, J M; Gracia, A; Martínez, I; García, N; Bermúdez de Castro, J M; Carbonell, E

    1999-05-20

    The Middle Pleistocene site of Sima de los Huesos in Sierra de Atapuerca, Spain, has yielded around 2,500 fossils from at least 33 different hominid individuals. These have been dated at more than 200,000 years ago and have been classified as ancestors of Neanderthals. An almost complete human male pelvis (labelled Pelvis 1) has been found, which we associate with two fragmentary femora. Pelvis 1 is robust and very broad with a very long superior pubic ramus, marked iliac flare, and a long femoral neck. This pattern is probably the primitive condition from which modern humans departed. A modern human newborn would pass through the birth canal of Pelvis 1 and this would be even larger in a female individual. We estimate the body mass of this individual at 95 kg or more. Using the cranial capacities of three specimens from Sima de los Huesos, the encephalization quotients are substantially smaller than in Neanderthals and modern humans.

  18. 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

  19. Freezing and post-thaw apoptotic behaviour of cells in the presence of palmitoyl nanogold particles

    Energy Technology Data Exchange (ETDEWEB)

    Thirumala, Sreedhar [Department of Mechanical Engineering, Louisiana State University, Baton Rouge, LA (United States); Forman, Julianne M [Department of Biological and Agricultural Engineering, Louisiana State University and Agricultural Center, Baton Rouge, LA (United States); Monroe, W Todd [Department of Biological and Agricultural Engineering, Louisiana State University and Agricultural Center, Baton Rouge, LA (United States); Devireddy, Ram V [Department of Mechanical Engineering, Louisiana State University, Baton Rouge, LA (United States)

    2007-05-16

    The aim of this study was to evaluate the freezing response of HeLa and Jurkat cells in the presence of commercially available nanoparticles, NPs (Palmitoyl Nanogold[reg], Nanoprobes). The cells were incubated with NPs for either 5 min or 3 h, and a calorimeter technique was then used to generate the volumetric shrinkage response during freezing at 20 deg. C min{sup -1}. Concomitantly, we also examined the effect of a commonly used cryoprotectant, dimethylsulfoxide, DMSO (10% v/v ratio) on the freezing response of HeLa and Jurkat cells. By fitting a model of water transport to the experimentally determined volumetric shrinkage data, the reference hydraulic conductivity, L{sub pg} ({mu}m/min-atm) and activation energy, E{sub Lp} (kcal mol{sup -1}) were obtained. For HeLa cells, the values of L{sub pg} ranged from 0.08 to 0.23 {mu}m/min-atm, while E{sub Lp} ranged from 10.9 to 37.4 kcal mol{sup -1}. For Jurkat cells these parameter values ranged from 0.05 to 0.16 {mu}m/min-atm and 9.5 to 35.9 kcal mol{sup -1}. A generic optimal cooling rate equation was then used to predict the optimal rates of freezing HeLa and Jurkat cells in the presence and absence of DMSO and NPs. The post-thaw viability and apoptotic response of HeLa and Jurkat cells was further investigated by cooling cells at three rates in the presence and absence of DMSO and NPs using a commercially available controlled rate freezer. Jurkat cells treated in this manner demonstrated an increase in their adhesive properties after 18 h incubation and adhered strongly to the bottom of the culture plate. This observation prevented further analysis of Jurkat apoptotic and necrotic post-thaw responses. There was no significant effect of NPs or DMSO alone on HeLa cell viability prior to freezing. The post-thaw results from HeLa cells show that the NPs increased the measured post-freeze apoptotic response when cooled at 1 deg. C min{sup -1}, suggesting a possible therapeutic use of NPs in cryodestructive procedures.

  20. Effect of soil property uncertainties on permafrost thaw projections: a calibration-constrained analysis

    Science.gov (United States)

    Harp, D. R.; Atchley, A. L.; Painter, S. L.; Coon, E. T.; Wilson, C. J.; Romanovsky, V. E.; Rowland, J. C.

    2016-02-01

    The effects of soil property uncertainties on permafrost thaw projections are studied using a three-phase subsurface thermal hydrology model and calibration-constrained uncertainty analysis. The null-space Monte Carlo method is used to identify soil hydrothermal parameter combinations that are consistent with borehole temperature measurements at the study site, the Barrow Environmental Observatory. Each parameter combination is then used in a forward projection of permafrost conditions for the 21st century (from calendar year 2006 to 2100) using atmospheric forcings from the Community Earth System Model (CESM) in the Representative Concentration Pathway (RCP) 8.5 greenhouse gas concentration trajectory. A 100-year projection allows for the evaluation of predictive uncertainty (due to soil property (parametric) uncertainty) and the inter-annual climate variability due to year to year differences in CESM climate forcings. After calibrating to measured borehole temperature data at this well-characterized site, soil property uncertainties are still significant and result in significant predictive uncertainties in projected active layer thickness and annual thaw depth-duration even with a specified future climate. Inter-annual climate variability in projected soil moisture content and Stefan number are small. A volume- and time-integrated Stefan number decreases significantly, indicating a shift in subsurface energy utilization in the future climate (latent heat of phase change becomes more important than heat conduction). Out of 10 soil parameters, ALT, annual thaw depth-duration, and Stefan number are highly dependent on mineral soil porosity, while annual mean liquid saturation of the active layer is highly dependent on the mineral soil residual saturation and moderately dependent on peat residual saturation. By comparing the ensemble statistics to the spread of projected permafrost metrics using different climate models, we quantify the relative magnitude of soil

  1. Identifying active methane-oxidizers in thawed Arctic permafrost by proteomics

    Science.gov (United States)

    Lau, C. M.; Stackhouse, B. T.; Chourey, K.; Hettich, R. L.; Vishnivetskaya, T. A.; Pfiffner, S. M.; Layton, A. C.; Mykytczuk, N. C.; Whyte, L.; Onstott, T. C.

    2012-12-01

    The rate of CH4 release from thawing permafrost in the Arctic has been regarded as one of the determining factors on future global climate. It is uncertain how indigenous microorganisms would interact with such changing environmental conditions and hence their impact on the fate of carbon compounds that are sequestered in the cryosol. Multitudinous studies of pristine surface cryosol (top 5 cm) and microcosm experiments have provided growing evidence of effective methanotrophy. Cryosol samples corresponding to active layer were sampled from a sparsely vegetated, ice-wedge polygon at the McGill Arctic Research Station at Axel Heiberg Island, Nunavut, Canada (N79°24, W90°45) before the onset of annual thaw. Pyrosequencing of 16S rRNA gene indicated the occurrence of methanotroph-containing bacterial families as minor components (~5%) in pristine cryosol including Bradyrhizobiaceae, Methylobacteriaceae and Methylocystaceae within alpha-Proteobacteria, and Methylacidiphilaceae within Verrucomicrobia. The potential of methanotrophy is supported by preliminary analysis of metagenome data, which indicated putative methane monooxygenase gene sequences relating to Bradyrhizobium sp. and Pseudonocardia sp. are present. Proteome profiling in general yielded minute traces of proteins, which likely hints at dormant nature of the soil microbial consortia. The lack of specific protein database for permafrost posted additional challenge to protein identification. Only 35 proteins could be identified in the pristine cryosol and of which 60% belonged to Shewanella sp. Most of the identified proteins are known to be involved in energy metabolism or post-translational modification of proteins. Microcosms amended with sodium acetate exhibited a net methane consumption of ~65 ngC-CH4 per gram (fresh weight) of soil over 16 days of aerobic incubation at room temperature. The pH in microcosm materials remained acidic (decreased from initial 4.7 to 4.5). Protein extraction and

  2. 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

  3. 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

  4. The interplay between inner and outer frost damage and its implication for accelerated freeze-thaw testing

    DEFF Research Database (Denmark)

    Hasholt, Marianne Tange

    2014-01-01

    In the present project salt frost scaling was registered during an accelerated freeze-thaw test (CEN/TS 12390-9). After the test, inner damage was evaluated by observing the crack patterns on fluorescence impregnated plane sections. The results indicate that the developments of inner and outer...

  5. Catalase supplementation on thawed bull spermatozoa abolishes the detrimental effect of oxidative stress on motility and DNA integrity.

    Science.gov (United States)

    Fernández-Santos, M R; Domínguez-Rebolledo, A E; Esteso, M C; Garde, J J; Martínez-Pastor, F

    2009-08-01

    The potential protective effect of catalase supplementation during in vitro culture of frozen/thawed bull spermatozoa was investigated. Frozen/thawed semen collected from three fighting bulls was diluted in phosphate buffered saline (PBS) and incubated at 37 degrees C under different experimental conditions: Control, Catalase (CAT) (200 U/mL), Oxidant (OXI) (100 microm Fe(2+)/1 mm ascorbate), and Catalase + Oxidant (CAT/OXI). We assessed sperm motility, acrosomal integrity, viability and chromatin status (SCSA) at 0, 2 and 6 h of incubation. Our results showed that catalase abolished the effect of the oxidant, protecting spermatozoa against reactive oxygen species, and improving both sperm motility and chromatin status during incubation. The OXI treatment significantly reduced the percentage of motile sperm after 6 h of incubation. The statistical model also showed that there were differences in sperm motility between CAT/OXI (20.8 +/- 2.9%) and OXI (11.6 +/- 7.6%) (p Catalase prevented DNA fragmentation even in the presence of the oxidant (%DFI: 30.3 +/- 0.8% OXI vs. 17.4 +/- 0.7% CAT/OXI). We conclude that catalase supplementation after thawing could protect bull spermatozoa against oxidative stress, and it could improve media used for processing thawed spermatozoa.

  6. Meat quality of lamb frozen stored up to 21 months: instrumental analyses on thawed meat during display.

    Science.gov (United States)

    Muela, E; Monge, P; Sañudo, C; Campo, M M; Beltrán, J A

    2015-04-01

    The study analysed the effect of frozen storage duration (FSD: 0, 1, 9, 15 or 21 months) and display duration (DD: 0-24 h post-slaughter-, 3 and 6 days) in modified atmosphere packaging (MAP) on lamb quality. pH, colour, lipid oxidation, water holding capacity and instrumental texture were performed on Longissimus muscle in displayed fresh and thawed meat. FSD affected all the variables showing lower differences between fresh and 1 month storage than among them and longer FSD. Only cooking losses were not affected by DD in thawed meats. It was observed a general decrease in quality (lower redness and water holding capacity; higher yellowness and lipid oxidation) as FSD or DD increased and only texture was improved over DD being thawed meat more tender. In conclusion, lamb storage at -18°C should not exceed 1 month if thawed meat would be later displayed in MAP while meat would have an acceptable quality up to 21 months without subsequent display. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. 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.

  8. Comparative Cryopreservation of Avian Spermatozoa: Effects of Cooling and Thawing Rates on Turkey and Sandhill Crane Sperm Cryosurvival

    Science.gov (United States)

    A comparative approach using Sandhill crane (Grus Canadensis) and the domestic white turkey (Meleagridis gallopavo) was used to determine the possible benefits of variation in cooling and thawing rates and semen volume on cryoprotective efficiency. Sperm was frozen in cryovials using a range of dime...

  9. Glutathione supplementation to semen extender improves the quality of frozen-thawed canine spermatozoa for transcervical insemination

    Science.gov (United States)

    OGATA, Kazuko; SASAKI, Aiko; KATO, Yuka; TAKEDA, Arisa; WAKABAYASHI, Mikio; SARENTONGLAGA, Borjigin; YAMAGUCHI, Mio; HARA, Asuka; FUKUMORI, Rika; NAGAO, Yoshikazu

    2015-01-01

    The present study was conducted to evaluate whether supplementation of semen extender with glutathione (GSH) can maintain the quality of frozen-thawed canine spermatozoa. Eighteen ejaculates were obtained from 5 dogs and placed in extender (20% egg yolk, Tris, citric acid, lactose, raffinose, antibiotics and 6.5% glycerol) containing 0 (control), 2.5, 5, 7.5 or 10 mM GSH. The samples were cooled to 4 C and then frozen in liquid nitrogen vapor. Motility parameters of the sperm were evaluated at 0, 1, 2, 3, 4, 12 and 24 h after thawing. Sperm motility was higher in the 5 mM GSH group than in the control or 2.5 and 10 mM GSH groups; this effect was observed at 1 to 24 h after thawing (P insemination of 4 bitches, resulting in delivery of 5 puppies from 2 bitches. These results indicate that supplementation of semen extender with 5 mM GSH was effective in improving motility, longevity and acrosomal integrity and inhibiting LP levels in post-thaw canine spermatozoa, without any adverse impacts on full-term development after transcervical insemination. PMID:25736550

  10. Effect of rapid freezing-thawing techniques on the sperm parameters and ultrastructure of Chinese Taihang black goat spermatozoa.

    Science.gov (United States)

    Shi, Liguang; Ren, Youshe; Zhou, Hanlin; Hou, Guanyu; Xun, Wenjuan; Yue, Wenbin; Zhang, Chunxiang; Yang, Rujie

    2014-02-01

    Supercooling sperm in liquid nitrogen vapour is a feasible and economic technique for the practical production. The study aimed to reveal the negative effects of this rapid freezing and thawing processes on Taihang black goat spermatozoa and to find out the changing of spermatozoa motility and ultrastructure by using CASA and TEM. Qualified semen samples, which collected from twenty Chinese Taihang black goats using artificial vagina were pooled and investigated the kinematics parameters and ultrastructural morphology. The results showed that freezing-thawing caused a significant reduction in the spermatozoon total motility (P<0.001), in rapid and medium cell numbers (P<0.001) and motility parameters (VAP, VSL, VCL, ALH and BCF) (P<0.01). Immotile spermatozoa number was increased significantly after freezing-thawing (P<0.001). In the ultrastructural analysis, the shape with a sperm nucleus characterized by ruptures, bend and deformity was observed. The plasma membranes were broken, and nucleoplasm erupted. The mitochondria in the middle piece were disturbed by partial absence or additional accumulations. Swelling, coiling, vacuolization and structural disorganization of mitochondria were also observed. In conclusion, Freezing-thawing procedure has a detrimental effect on motility, membrane integrity and mitochondria of goat spermatozoa. Transmission electron microscopy provides an intuitive observation to investigate deformity spermatozoa. Copyright © 2013 Elsevier Ltd. All rights reserved.

  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

    synergy between freeze-thaw cycles and copper stress, leading to an elevated mortality of enchytraeids subjected to these conditions. Enchytraeids subjected to conditions of constant freezing and copper stress were not as severely affected. To examine this synergy an array of analyses were conducted...

  12. 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

  13. Effects of permafrost thaw on carbon emissions under aerobic and anaerobic environments in the Great Hing'an Mountains, China.

    Science.gov (United States)

    Song, Changchun; Wang, Xianwei; Miao, Yuqing; Wang, Jiaoyue; Mao, Rong; Song, Yanyu

    2014-07-15

    The carbon (C) pool of permafrost peatland is very important for the global C cycle. Little is known about how permafrost thaw could influence C emissions in the Great Hing'an Mountains of China. Through aerobic and anaerobic incubation experiments, we studied the effects of permafrost thaw on CH4 and CO2 emissions. The rates of CH4 and CO2 emissions were measured at -10, 0 and 10°C. Although there were still C emissions below 0°C, rates of CH4 and CO2 emissions significantly increased with permafrost thaw under aerobic and anaerobic conditions. The C release under aerobic conditions was greater than under anaerobic conditions, suggesting that permafrost thaw and resulting soil environment change should be important influences on C emissions. However, CH4 stored in permafrost soils could affect accurate estimation of CH4 emissions from microbial degradation. Calculated Q10 values in the permafrost soils were significantly higher than values in active-layer soils under aerobic conditions. Our results highlight that permafrost soils have greater potential decomposability than soils of the active layer, and such carbon decomposition would be more responsive to the aerobic environment. © 2013 Elsevier B.V. All rights reserved.

  14. TEMPORARY STORAGE OF BOVINE SEMEN CRYOPRESERVED IN LIQUID NITROGEN ON DRY ICE AND REFREEZING OF FROZEN-THAWED SEMEN.

    Science.gov (United States)

    Abdussamad, A M; Gauly, M; Holtz, W

    2015-01-01

    Two experiments were conducted. The purpose of Experiment 1 was to investigate whether viability of bovine semen stored in liquid nitrogen (-196°C) will be adversely affected by temporary exposure to dry ice (-79°C). It was convincingly shown that post thaw-motility was not affected, regardless whether semen was thawed immediately or after being returned to liquid nitrogen. Shipping or temporary storage on dry ice, thus, is a viable option. In Experiment 2, refreezing of frozen-thawed semen was attempted. The proportion of motile spermatozoa was reduced by a factor of ten to between 6.0 % and 7.4 %, regardless whether thawing occurred directly after removal from liquid nitrogen or after an interim period on dry ice. When semen was refrozen on dry ice before being returned to liquid nitrogen, motility rates were significantly improved (13.0 % to 17.0 %, P<0.05). In both experiments sperm cells that remained motile displayed vigorous forward movement and normal morphological appearance.

  15. 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

  16. Microbial community response to permafrost thaw after wildfire in an Alaskan upland boreal forest

    Science.gov (United States)

    Tas, N.; Jorgenson, M. T.; Wang, S.; Berhe, A. A.; Wickland, K. P.; Waldrop, M. P.; Jansson, J. K.

    2012-12-01

    Fire is a major factor controlling the long-term dynamics of soil carbon in Alaskan boreal forests. Wildfire not only contributes to a significant global emission of greenhouse gasses but also can indirectly result in the deepening of the active layer and thawing of near-surface permafrost due to reductions in organic layer depth and increases in heat flux through soil. Although boreal ecosystems are fire-adapted, increased fire frequency and rising global temperatures may result in warmer soils and therefore increase the metabolic rates of decomposer microbes and result in accelerated permafrost decomposition and greenhouse gas fluxes. In addition to fire-mediated changes in soil and vegetation structure, changes in the soil microbial community structure are likely to have consequences for rates of soil carbon cycling. In this study we aimed to define the impact of fire on soil microbial communities in an upland black spruce forest and to assess microbial metabolic potential for soil respiration, methanogenesis, and nitrous oxide (N2O) flux. Soil samples from two fire impacted and three control (unburned) locations were collected near Nome Creek, AK, an upland moderately drained black spruce forest. This location was within the Boundary fire that burned between mid-June and the end of August 2004. Soil temperature measurements from before and after the fire showed that soils were warmer after the fire event and the permafrost thawed below 1m. At each sampling location, soil and permafrost samples were collected every 10 cm to a depth of 1 m. Besides biochemical characterization, CO2, CH4, N2O fluxes and potential activities of enzymes involved in extracellular decomposition of complex organic molecules (hemicellulose, chitin and lignin) were measured. The microbial community composition in the samples was determined by sequencing of 16S rRNA genes and microbial metabolic potential was assessed via sequencing of total genomic DNA (metagenomics) in selected active

  17. 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

  18. 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.

  19. Physically Accurate Soil Freeze-Thaw Processes in a Global Land Surface Scheme

    Science.gov (United States)

    Cuntz, Matthias; Haverd, Vanessa

    2014-05-01

    Transfer of energy and moisture in frozen soil, and hence the active layer depth, are strongly influenced by the soil freezing curve which specifies liquid moisture content as a function of temperature. However, the curve is typically not represented in global land surface models, with less physically-based approximations being used instead. In this work, we develop a physically accurate model of soil freeze-thaw processes, suitable for use in a global land surface scheme. We incorporated soil freeze-thaw processes into an existing detailed model for the transfer of heat, liquid water and water vapor in soils, including isotope diagnostics - Soil-Litter-Iso (SLI, Haverd & Cuntz 2010), which has been used successfully for water and carbon balances of the Australian continent (Haverd et al. 2013). A unique feature of SLI is that fluxes of energy and moisture are coupled using a single system of linear equations. The extension to include freeze-thaw processes and snow maintains this elegant coupling, requiring only coefficients in the linear equations to be modified. No impedance factor for hydraulic conductivity is needed because of the formulation by matric flux potential rather than pressure head. Iterations are avoided which results in the same computational speed as without freezing. The extended model is evaluated extensively in stand-alone mode (against theoretical predictions, lab experiments and field data) and as part of the CABLE global land surface scheme. SLI accurately solves the classical Stefan problem of a homogeneous medium undergoing a phase change. The model also accurately reproduces the freezing front, which is observed in laboratory experiments (Hansson et al. 2004). SLI was further tested against observations at a permafrost site in Tibet (Weismüller et al. 2011). It reproduces seasonal thawing and freezing of the active layer to within 3 K of the observed soil temperature and to within 10% of the observed volumetric liquid soil moisture

  20. 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......–105 cm as a result of a 2–6 °C warming. An additional increase in the maximum active layer thickness of a few centimetres may be expected due to heat production from decomposition of organic matter. Simulated future soil temperatures and water contents are subsequently used with measured basal soil...

  1. 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.

  2. 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

  3. Addition of Tempol in semen cryopreservation medium improves the post-thaw sperm function.

    Science.gov (United States)

    Bateni, Zahra; Azadi, Leila; Tavalaee, Marziyeh; Kiani-Esfahani, Abbas; Fazilati, Mohammad; Nasr-Esfahani, Mohammad Hossein

    2014-08-01

    Despite extensive research carried out for optimization and commercialization of sperm cryopreservation media, percentage of motility and viability remain low following cryopreservation. These adverse effects have been partially ascribed to reactive oxygen species (ROS) production during cryopreservation. Therefore, we proposed that addition of a cell permeable antioxidant like Tempol, with superoxide dismutase (SOD) mimetic action, may overcome these effects in an optimized commercially available cryo-protective medium. Therefore, semen samples were cryopreserved in the presence or absence of Tempol. A concentration of 5 μM Tempol was defined as optimal since it significantly improved motility and viability post thawing and reduced DNA fragmented sperm. In addition, percentage of ROS positive sperm was reduced. These effects of Tempol can be attributed to cell permeability characteristic and ability to reduce superoxide production both at intra- and extra-cellular levels. Tempol may hold the potential for clinical applications.

  4. 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

  5. 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

    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...... 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...

  6. Fertility response of artificial insemination methods in sheep with fresh and frozen-thawed semen.

    Science.gov (United States)

    Masoudi, Reza; Zare Shahneh, Ahmad; Towhidi, Armin; Kohram, Hamid; Akbarisharif, Abbas; Sharafi, Mohsen

    2017-02-01

    The aim of this study was to evaluate the fertility response of artificial insemination (AI) methods with fresh and frozen sperm in sheep. In experiment 1, one hundred and fifty fat tailed Zandi ewes were assigned into 3 equal groups and inseminated with three AI methods consisting of vaginal, laparoscopic and trans-cervical AI with fresh semen. In experiment 2, a factorial study (3 AI methods × 2 extenders) was used to analyze the effects of three AI methods and two freezing extenders containing soybean lecithin (SL) or Egg yolk (EY) on reproductive performance of 300 fat tailed Zandi ewes. Also, total motility, progressive motility, viability and lipid peroxidation of semen were evaluated after freeze-thawing in two extenders. In result, there was no significant difference among three AI methods when fresh semen was used. In experiment 2, the highest percentage of pregnancy rate, parturition rate and lambing rate were obtained in laparoscopic AI group (P < 0.05). Although pregnancy rate, parturition rate and lambing rate in trans-cervical group were higher (P < 0.05) than vaginal group, the results were not as high as laparoscopic group. No difference was observed between SL and EY extenders and their performance was close to each other. It can be concluded that although no difference was observed on reproductive performance for fresh semen, trans-cervical AI was more efficient than vaginal method when frozen-thawed semen was used, but its efficiency was not as high as laparoscopic method. Also, SL extender can be an efficient alternative extender to preserve ram sperm during cryopreservation procedure without adverse effects of EY. Copyright © 2016. Published by Elsevier Inc.

  7. Time lapse imaging of thaw-bulb development beneath arctic streams using ground-penetrating radar

    Science.gov (United States)

    Brosten, T. R.; Bradford, J. H.; McNamara, J. P.; Bowden, W.; Gooseff, M. N.

    2004-12-01

    We are investigating the responses of arctic tundra stream geomorphology, hyporheic zone hydrology, and biogeochemical cycling to climate change. Field results from summer, 2003, demonstrate that GPR is an effective tool for imaging the depth to sub-stream permafrost. The results presented here are the next step in the use of ground-penetrating radar (GPR) data for measuring sub-stream thaw over the summer season. We acquired a series of GPR profiles at seven sites from May - September, 2004, using 100, 200, and 400 MHz antennas. We selected sites with the objective of including stream reaches spanning a range of geomorphologic conditions in rivers and streams on Alaska's North Slope. Generally the streams can be placed into two categories: 1) as low-energy water flow with organic material lining the streambeds (peat streams) or 2) as high-energy water flow with cobble to gravel material lining the streambeds (alluvial streams). We acquired data using a pulsed radar system with high-power transmitter. Early in the field season we used the 400 and 200 MHz antennas to maximize resolution potential, then gradually shifted to the lower frequency 100 MHz antennas later in the season to increase depth of penetration. We placed the radar antennas in the bottom of a small rubber boat, then pulled the boat across the bank and through the stream while triggering at a constant interval via a string odometer system. Depth to permafrost was verified by pressing a metal probe through the active layer to the point of refusal. In addition, we recorded temperature data using thermocouples placed at varying substream depths along two of the seven GPR profiles. We used the temperature profiles to constrain and verify the GPR interpretation. At several sites we obtained excellent results and have produced images of thaw-bulb growth through the summer season in both alluvial and peat stream morphologies.

  8. 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

  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. 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.

  11. Effect of sex-sorting and cryopreservation on the post-thaw sperm quality of Iberian red deer spermatozoa.

    Science.gov (United States)

    Anel-López, L; García-Álvarez, O; Parrilla, I; Del Olmo, D; Maroto-Morales, A; Fernandez-Santos, M R; Ortiz, J A; Soler, A J; Martínez, E M; Vazquez, J M; Garde, J J

    2017-02-01

    This study investigated the effect of sex-sorting and cryopreservation on post-thaw characteristics and fertility of red deer (Cervus elaphus) sperm for the first time. Semen was collected by electroejaculation from 10 mature stags during the breeding season, and each ejaculate split into four experimental groups: Bulk sorted spermatozoa, sorted but not sexed (BSS); sorted high purity X-spermatozoa (XSS); sorted high purity Y-spermatozoa (YSS); and, control non-sorted spermatozoa (NS). Following, all samples were frozen over liquid nitrogen. Two straws per stag and sample type were analyzed immediately post-thaw and following a 2-h incubation period at 37 °C. Post-thaw total motility (TM) as assessed by CASA was not different (P  0.05) to that of YSS (47%) sperm. The percentage of apoptotic spermatozoa as assessed by PI/YO-PRO-1 and flow cytometry analysis, was higher (17%, P ≤ 0.05) for XSS sperm than NS (12%), BSS (13%) and YSS (14%) sperm. Following incubation there were no differences (P > 0.05) in TM or percent apoptosis among treatments. Post-thaw chromatin stability calculated as the DNA fragmentation index (%DFI) was similar among treatments; following incubation %DFI increased in all except YSS, which displayed the lowest value (P spermatozoa, respectively (P < 0.05). In summary, Y-sorted sperm displayed acceptable post-thaw sperm evaluation parameters and the expected offspring sex ratio. More studies are needed to understand the source of sperm damage that may compromise the fertility of Y-sorted red deer sperm. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Effect of addition of coconut water (Cocos nucifera) to the freezing media on post-thaw viability of boar sperm.

    Science.gov (United States)

    Bottini-Luzardo, María; Centurión-Castro, Fernando; Alfaro-Gamboa, Militza; Aké-López, Ricardo; Herrera-Camacho, José

    2013-01-01

    The aims of this experiment were to evaluate the addition of coconut water in natura to the freezing media, compare the effect of deionized water vs filtered water of coconut over the post-thaw seminal characteristics, and evaluate the effect of the deionized water and in natura coconut water on the seminal characteristics of boar sperm at different post-thaw times. Thirty-four ejaculates were used divided in three aliquots which received one of the following treatments (T): T1, LEY (bidistilled water, lactose, and egg yolk) and LEYGO (LEY + glycerol and Orvus ET paste); T2, LEY(A) (coconut deionized water, lactose, and egg yolk)-LEYGO(A); and T3, LEY(B) (in natura coconut water, lactose, and egg yolk)-LEYGO(B). Samples of boar semen were frozen according to the Westendorf method, thawed at 38°C, and evaluated at three incubation times (0, 30, and 60 min). Seminal characteristics assessed were motility (Mot), acrosomal integrity (AInt), membrane integrity (MInt), and mitochondrial activity (MAct). T1 showed a higher percentage of viable sperm than T3 (Mot 36.5 vs 5.4 %, AInt 61.8 vs 41.2 %, MInt 50.4 vs 41.3 %, and MAct 56.9 vs 50.5 %). T2 kept a higher percentage of viable sperm at all incubation times. In natura coconut water showed a detrimental effect over the viability of the frozen-thawed boar semen. Deionized coconut water improved the boar semen viability post-thaw, outperforming results of in natura coconut water.

  13. 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.

  14. Embalmed and fresh frozen human bones in orthopedic cadaveric studies: which bone is authentic and feasible?

    Science.gov (United States)

    Topp, Tobias; Müller, Thorben; Huss, Sebastian; Kann, Peter Herbert; Weihe, Eberhard; Ruchholtz, Steffen; Zettl, Ralph Peter

    2012-10-01

    The most frequently used bones for mechanical testing of orthopedic and trauma devices are fresh frozen cadaveric bones, embalmed cadaveric bones, and artificial composite bones. Even today, the comparability of these different bone types has not been established. We tested fresh frozen and embalmed cadaveric femora that were similar concerning age, sex, bone mineral density, and stiffness. Artificial composite femora were used as a reference group. Testing parameters were pullout forces of cortex and cancellous screws, maximum load until failure, and type of fracture generated. Stiffness and type of fracture generated (Pauwels III) were similar for all 3 bone types (fresh frozen: 969 N/mm, 95% confidence interval (CI): 897-1,039; embalmed: 999 N/mm, CI: 875-1,121; composite: 946 N/mm, CI: 852-1,040). Furthermore, no significant differences were found between fresh frozen and embalmed femora concerning pullout forces of cancellous screws (fresh frozen: 654 N, CI: 471-836; embalmed: 595 N, CI: 365-823) and cortex screws (fresh frozen: 1,152 N, CI: 894-1,408; embalmed: 1,461 N, CI: 880-2,042), and axial load until failure (fresh frozen: 3,427 N, CI: 2,564-4290; embalmed: 3,603 N, CI: 2,898-4,306). The reference group showed statistically significantly different results for pullout forces of cancellous screws (2,344 N, CI: 2,068-2,620) and cortex screws (5,536 N, CI: 5,203-5,867) and for the axial load until failure (> 7,952 N). Embalmed femur bones and fresh frozen bones had similar characteristics by mechanical testing. Thus, we suggest that embalmed human cadaveric bone is a good and safe option for mechanical testing of orthopedic and trauma devices.

  15. 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.

  16. Effect of single-layer centrifugation or washing on frozen-thawed donkey semen quality: Do they have the same effect regardless of the quality of the sample?

    Science.gov (United States)

    Ortiz, I; Dorado, J; Morrell, J M; Crespo, F; Gosálvez, J; Gálvez, M J; Acha, D; Hidalgo, M

    2015-07-15

    The aims of this study were to determine the sperm quality of frozen-thawed donkey sperm samples after single-layer centrifugation (SLC) using Androcoll-E in comparison to sperm washing or no centrifugation and to determine if the effect on the sperm quality after SLC or sperm washing depends on the quality of the sample. Frozen-thawed sperm samples from Andalusian donkeys were divided into three aliquots, and they were processed using three different techniques after thawing: uncentrifuged diluted control (UDC), sperm washing (SW), and SLC. Afterward, sperm quality index was estimated by integrating all parameters (total and progressive sperm motility, membrane integrity, and DNA fragmentation) in a single value. The relationship between the sperm quality of thawed UDC samples and the effect on sperm parameters in SW and SLC-selected samples was assessed. Sperm quality index was significantly higher (P < 0.001) in SLC (0.8 ± 0.0) samples than that in UDC (0.6 ± 0.0) and SW (0.6 ± 0.0) samples, regardless of the sperm quality index after thawing of the sperm sample. In conclusion, SLC of frozen-thawed donkey spermatozoa using Androcoll-E-Small can be a suitable procedure for selecting frozen-thawed donkey sperm with better quality, in particular in those samples where an improvement in motility is needed. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. Localization of Minodronate in Mouse Femora Through Isotope Microscopy

    Science.gov (United States)

    Hongo, Hiromi; Sasaki, Muneteru; Kobayashi, Sachio; Hasegawa, Tomoka; Yamamoto, Tomomaya; Tsuboi, Kanako; Tsuchiya, Erika; Nagai, Tomoya; Khadiza, Naznin; Abe, Miki; Kudo, Ai; Oda, Kimimitsu; Henrique Luiz de Freitas, Paulo; Li, Minqi; Yurimoto, Hisayoshi; Amizuka, Norio

    2016-01-01

    Minodronate is highlighted for its marked and sustained effects on osteoporotic bones. To determine the duration of minodronate’s effects, we have assessed the localization of the drug in mouse bones through isotope microscopy, after labeling it with a stable nitrogen isotope ([15N]-minodronate). In addition, minodronate-treated bones were assessed by histochemistry and transmission electron microscopy (TEM). Eight-week-old male ICR mice received [15N]-minodronate (1 mg/kg) intravenously and were sacrificed after 3 hr, 24 hr, 1 week, and 1 month. Isotope microscopy showed that [15N]-minodronate was present mainly beneath osteoblasts rather than nearby osteoclasts. At 3 hr after minodronate administration, histochemistry and TEM showed osteoclasts with well-developed ruffled borders. However, osteoclasts were roughly attached to the bone surfaces and did not feature ruffled borders at 24 hr after minodronate administration. The numbers of tartrate-resistant acid phosphatase–positive osteoclasts and alkaline phosphatase–reactive osteoblastic area were not reduced suddenly, and apoptotic osteoclasts appeared in 1 week and 1 month after the injections. Von Kossa staining demonstrated that osteoclasts treated with minodronate did not incorporate mineralized bone matrix. Taken together, minodronate accumulates in bone underneath osteoblasts rather than under bone-resorbing osteoclasts; therefore, it is likely that the minodronate-coated bone matrix is resistant to osteoclastic resorption, which results in a long-lasting and bone-preserving effect. PMID:27666429

  18. Localization of Minodronate in Mouse Femora Through Isotope Microscopy.

    Science.gov (United States)

    Hongo, Hiromi; Sasaki, Muneteru; Kobayashi, Sachio; Hasegawa, Tomoka; Yamamoto, Tomomaya; Tsuboi, Kanako; Tsuchiya, Erika; Nagai, Tomoya; Khadiza, Naznin; Abe, Miki; Kudo, Ai; Oda, Kimimitsu; Henrique Luiz de Freitas, Paulo; Li, Minqi; Yurimoto, Hisayoshi; Amizuka, Norio

    2016-10-01

    Minodronate is highlighted for its marked and sustained effects on osteoporotic bones. To determine the duration of minodronate's effects, we have assessed the localization of the drug in mouse bones through isotope microscopy, after labeling it with a stable nitrogen isotope ([(15)N]-minodronate). In addition, minodronate-treated bones were assessed by histochemistry and transmission electron microscopy (TEM). Eight-week-old male ICR mice received [(15)N]-minodronate (1 mg/kg) intravenously and were sacrificed after 3 hr, 24 hr, 1 week, and 1 month. Isotope microscopy showed that [(15)N]-minodronate was present mainly beneath osteoblasts rather than nearby osteoclasts. At 3 hr after minodronate administration, histochemistry and TEM showed osteoclasts with well-developed ruffled borders. However, osteoclasts were roughly attached to the bone surfaces and did not feature ruffled borders at 24 hr after minodronate administration. The numbers of tartrate-resistant acid phosphatase-positive osteoclasts and alkaline phosphatase-reactive osteoblastic area were not reduced suddenly, and apoptotic osteoclasts appeared in 1 week and 1 month after the injections. Von Kossa staining demonstrated that osteoclasts treated with minodronate did not incorporate mineralized bone matrix. Taken together, minodronate accumulates in bone underneath osteoblasts rather than under bone-resorbing osteoclasts; therefore, it is likely that the minodronate-coated bone matrix is resistant to osteoclastic resorption, which results in a long-lasting and bone-preserving effect. © 2016 The Histochemical Society.

  19. 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

  20. Early thawing after snow removal and no straw mulching accelerates organic carbon cycling in a paddy soil in Northeast China.

    Science.gov (United States)

    Zhang, Hao; Tang, Jie; Liang, Shuang; Li, Zhaoyang; Wang, Jingjing; Wang, Sining

    2018-03-01

    Variations in soil organic carbon (SOC) have implications for atmospheric CO 2 concentrations and the greenhouse effect. However, the effects of snow cover and straw mulching on the variations in SOC fractions across winter remain largely unknown. In this study, soil samples were collected during different stages of winter from an in situ experiment comprising three treatments: 1) snow removal with no straw mulching (Sn-SM-); 2) snow cover with no straw mulching (SC), and; 3) snow cover with straw mulching (SC + SM+). Results showed that labile organic carbon, semi-labile organic carbon, recalcitrant organic carbon (ROC), the light fraction of organic carbon (LFOC), and easily oxidized organic carbon (EOC) contents did not vary significantly (P > .05) during the unfrozen to hard frost stages. Compared to the unfrozen stage, microbial biomass carbon (MBC) contents decreased by 519.03 mg kg -1 , 325.21 mg kg -1 , and 244.09 mg kg -1 and dissolved organic carbon (DOC) contents increased by 473.36 mg kg -1 , 348.10 mg kg -1 , and 258.89 mg kg -1  at the hard frost stage in Sn-SM-, SC, and SC + SM + treatments, respectively. Throughout all thawing stages, > 61% and 59% of SOC and ROC accumulation, respectively in the three treatments were observed in thawing stage II, indicating that higher temperatures and microbial activities in thawing stage II accelerated the inputs of SOC and ROC. ROC accumulation accounted for >65% of the SOC accumulation and the proportions of ROC in SOC increased in the three treatments during the thawing stages. SC + SM + treatment maintained lower EOC contents during thawing stages than other treatments. The observation of lowest SOC and LFOC accumulation and contents in the SC + SM + treatment during thawing stages showed that SC + SM + experienced the least inputs of SOC in the soil. Copyright © 2018 Elsevier Ltd. All rights reserved.

  1. 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

  2. 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

  3. Variations in soil carbon dioxide efflux across a thaw slump chronosequence in northwestern Alaska

    International Nuclear Information System (INIS)

    Jensen, A E; Crosby, B T; Lohse, K A; Mora, C I

    2014-01-01

    Warming of the arctic landscape results in permafrost thaw, which causes ground subsidence or thermokarst. Thermokarst formation on hillslopes leads to the formation of thermal erosion features that dramatically alter soil properties and likely affect soil carbon emissions, but such features have received little study in this regard. In order to assess the magnitude and persistence of altered emissions, we use a space-for-time substitution (thaw slump chronosequence) to quantify and compare peak growing season soil carbon dioxide (CO 2 ) fluxes from undisturbed tundra, active, and stabilized thermal erosion features over two seasons. Measurements of soil temperature and moisture, soil organic matter, and bulk density are used to evaluate the factors controlling soil CO 2 emissions from each of the three chronosequence stages. Soil CO 2 efflux from the active slump is consistently less than half that observed in the undisturbed tundra or stabilized slump (1.8 versus 5.2 g CO 2 −C m −2  d −1 in 2011; 0.9 versus 3.2 g CO 2 −C m −2  d −1 in 2012), despite soil temperatures on the floor of the active slump that are 10–15  ° C warmer than the tundra and stabilized slump. Environmental factors such as soil temperature and moisture do not exert a strong control on CO 2 efflux, rather, local soil physical and chemical properties such as soil organic matter and bulk density, are strongly and inversely related among these chronosequence stages (r 2 = 0.97), and explain ∼50% of the variation in soil CO 2 efflux. Thus, despite profound soil warming and rapid exposure of buried carbon in the active slump, the low organic matter content, lack of stable vegetation, and large increases in the bulk densities in the uppermost portion of active slump soils (up to ∼2.2 g −1  cm −3 ) appear to limit CO 2 efflux from the active slump. Future studies should assess seasonal fluxes across these features and determine whether soil CO 2 fluxes from active

  4. 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

  5. Raffinose and hypotaurine improve the post-thawed Merino ram sperm parameters.

    Science.gov (United States)

    Bucak, Mustafa Numan; Keskin, Nazan; Taşpınar, Mehmet; Çoyan, Kenan; Başpınar, Nuri; Cenariu, Mihai C; Bilgili, Ali; Öztürk, Caner; Kurşunlu, Ahmet Nuri

    2013-08-01

    The aim of this study was to determine the effects of raffinose and hypotaurine on sperm parameters after the freeze-thawing of Merino ram sperm. Totally 40 ejaculates of five Merino ram were used in the study. Semen samples, which were diluted with a Tris-based extender containing 10mM raffinose, 5mM hypotaurine, 5mM raffinose +2.5mM hypotaurine (H+R) and no antioxidant (control), were cooled to 5 °C and frozen in 0.25 ml French straws and stored in liquid nitrogen. Frozen straws were then thawed individually at 37 °C for 25s in a water bath for evaluation. The addition of raffinose led to higher percentages of subjective and CASA motilities (47.5 ± 12.2%, 46.3 ± 13.6%) compared to controls (38.8 ± 13.8%, 30.5 ± 11.7%, Pcontrol (10 ± 7.94%, Pprocess. Raffinose and hypotaurine led to higher viability (40.8 ± 4.68%, 40.8 ± 4.7%), high sperm mitochondrial activity (29.5 ± 5.4%, 27.3 ± 4.9%) and acrosome integrity (50.8 ± 8.1, 50.7 ± 4.4) percentages, compared to control groups (31.5 ± 3.5%, 9.5 ± 8.2%, 42.8 ± 7.3%, Pcontrol group. In the comet test, raffinose and hypotaurine resulted in lower sperm with damaged DNA (6.2% and 3.9%) than that of control (9.1%), reducing the DNA damage. For TUNEL assay, The TUNEL-positive cell was distinguished by distinct nuclear staining. Raffinose and H+R groups resulted in lower sperm with TUNEL-positive cell (1.5 ± 1.2% and 2.1 ± 0.9%) than that of control (4.9 ± 2.5%) (Pcontrol groups. Crown Copyright © 2013. Published by Elsevier Inc. All rights reserved.

  6. 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

  7. The role of intergenerational influence in waste education programmes: The THAW project

    International Nuclear Information System (INIS)

    Maddox, P.; Doran, C.; Williams, I.D.; Kus, M.

    2011-01-01

    Highlights: → Children can be effective advocates in changing their parents' lifestyles. → We investigated the role of intergenerational influence in waste education programmes. → Waste Watch's Take Home Action on Waste project worked with 6705 children in 39 schools. → The results showed increased participation in recycling and declines in residual waste. → The study shows that recycling behaviour is positively impacted by intergenerational influence. - Abstract: 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

  8. Effects of glycerol, equilibration time and antioxidants on post-thaw functional integrity of bovine spermatozoa directly obtained from epididymis.

    Science.gov (United States)

    Almeida, F C; Silva, S V; Souza, H M; Gomes, W A; Lima Filho, J A C; Wicke, A A; Batista, A M; Guerra, M M P

    2017-04-01

    This work aimed to evaluate the effect of stabilisation times, glycerol concentration, and the catalase and superoxide dismutase supplementation of diluent on parameters of frozen-thawed spermatozoa from epididymis of Nelore bulls: Experiment 1: spermatozoa diluted in Tris-egg yolk with glycerol (3%, 5% or 7%) and stabilisation times (0, 2 or 4 hr at 5°C); Experiment 2: Tris-egg yolk only, Tris-egg yolk with catalase (CAT, 50 or 100 U ml -1 ) or superoxide dismutase (SOD, 50 or 100 U ml -1 ). Frozen-thawed spermatozoa were evaluated for kinetic parameters, plasma membrane and acrosome integrity, mitochondrial activity and IVF capacity. ALH and BCF were affected (p spermatozoa from epididymis of Nelore bulls. © 2016 Blackwell Verlag GmbH.

  9. 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.

  10. 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

    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...... 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...... 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...

  11. 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...... of selected quality attributes as drip loss, water holding capacity and content of dimethylamine by NIR was evaluated. The results of the investigation were presented using multivariate modelling methods such as partial least- squares regression (PLSR) and discriminant partial least- squares regression (DPLSR......Near-infrared reflectance (NIR) spectra was recorded of 105 samples of cod mince prepared from chill stored thawed cod fillets of varying quality in modified atmosphere packaging (MAP). Traditional chemical, physical, microbiological and sensory quality methods developed for assessing fresh fish...

  12. Laboratory freeze-thaw durability of pervious concrete with respect to curing time and addition of sand, slag, silica fume, and saltguard.

    Science.gov (United States)

    2016-11-22

    Concerns persist regarding pervious concrete durability in cold climates related to freeze-thaw : and exposure to salt. This study was conducted as an extension to previous work regarding pervious : concrete in Vermont, to further investigate freeze-...

  13. Effects of curing methods and supplementary cementitious material use on freeze thaw durability of concrete containing d-cracking aggregates : [technical summary].

    Science.gov (United States)

    2013-12-01

    For concrete pavements in Kansas, the most effective method of increasing their sustainability is to increase the service life. One of the principle mechanism of concrete pavement deterioration in Kansas is freezing and thawing damage. Some Kansas li...

  14. 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.

  15. A dynamic ecosystem process model for understanding interactions between permafrost thawing and vegetation responses in the arctic

    Science.gov (United States)

    Xu, C.; Travis, B. J.; Fisher, R. A.; Wilson, C. J.; McDowell, N.

    2010-12-01

    The arctic is expected to play an important role in the Earth’s future climate due to the large carbon stocks that are stored in permafrost and peatlands, a substantial proportion of which may be released to the atmosphere due to permafrost thawing. There may be positive feedbacks of permafrost thawing on plant growth by releasing stored nitrogen and increasing rooting depth; however, vegetation response to other changing variables such as CO2 and temperature can also modify soil hydrology and energy fluxes, leading to either positive or negative feedbacks on permafrost thawing. Disentangling the interactions between permafrost thawing and vegetation growth is critical for assessing the potential role of arctic regions on current and future global carbon cycling. We have developed a mechanistic, regional, and spatially explicit dynamic ecosystem process model through the integration of a 3-D soil hydrology and biogeochemistry model (Arctic Hydrology, ARCHY) and a dynamic vegetation model (Ecosystem Demography, ED), to quantify the importance of plant-permafrost interactions to soil and plant carbon storage. This model integrates important processes including photosynthesis, transpiration, respiration, 3-D competition for light, 3-D soil hydrology, energy fluxes (ice melting in the soil and solar radiation interception by canopy), nitrogen cycles (microbial decomposition, nitrogen transportation in soil, passive and active nitrogen uptake by plants), species migration, and drought-related mortality. A sensitivity analysis has been implemented to assess the importance of the hydrological cycle, the nitrogen cycle and energy fluxes in regulating the above and below-ground carbon cycles in arctic regions. Our model can fill an important gap between field and global land surface models for assessing plot and regional level hypotheses in the context of global climate.

  16. 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.

  17. Sperm cryopreservation of the Indian major carp, Labeo calbasu: effects of cryoprotectants, cooling rates and thawing rates on egg fertilization.

    Science.gov (United States)

    Nahiduzzaman, Md; Hassan, Md Mahbubul; Roy, Pankoz Kumar; Hossain, Md Akhtar; Hossain, Mostafa Ali Reza; Tiersch, Terrence R

    2012-12-01

    A sperm cryopreservation protocol for the Indian major carp, Labeo calbasu, was developed for long-term preservation and artificial fertilization. Milt collected from mature male fish were placed in Alsever's solution (296mOsmolkg(-1)) to immobilize the sperm. Cryoprotectant toxicity was evaluated by motility assessment with dimethyl sulfoxide (DMSO) and methanol at 5, 10 and 15% concentrations. DMSO was more toxic at higher concentrations than methanol, and consequently 15% DMSO was excluded from further study. A one-step cooling protocol (from 5 to 80°C) with two cooling rates (5 and 10°C/min) was carried out in a computer-controlled freezer (FREEZE CONTROL(®) CL-3300; Australia). Based on post-thaw motility, the 10°C/min cooling rate with either 10% DMSO or 10% methanol yielded significantly higher (P=0.011) post-thaw motility than the other rate and cryoprotectant concentrations. Sperm thawed at 40°C for 15s and fresh sperm were used to fertilize freshly collected L. calbasu eggs and significant differences were observed (P=0.001) in percent fertilization between cryopreserved and fresh sperm as well as among different sperm-to-egg ratios (P=0.001). The highest fertilization and hatching rates were observed for thawed sperm at a sperm-to-egg ratio of 4.1×10(5):1. The cryopreservation protocol developed can facilitate hatchery operations and long-term conservation of genetic resources of L. calbasu. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. 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...

  19. 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

  20. Response of thawed epididymal red deer spermatozoa to increasing concentrations of hydrogen peroxide, and importance of individual male variability.

    Science.gov (United States)

    Domínguez-Rebolledo, A E; Martínez-Pastor, F; Bisbal, A F; Ros-Santaella, J L; García-Álvarez, O; Maroto-Morales, A; Soler, A J; Garde, J J; Fernández-Santos, M R

    2011-06-01

    Oxidative stress represents a challenge during sperm manipulation. We have tested the effect of increasing hydrogen peroxide (H(2)O(2)) levels on red deer spermatozoa after cryopreservation, and the role of male-to-male variation in that response. In a first experiment, eight thawed samples were submitted to 0, 25, 50, 100 and 200 μm H(2)O(2) for 2 h at 37 °C. Intracellular reactive oxygen species (H(2)DCFDA-CM) increased with H(2)O(2) concentration, but we only detected a decrease in sperm function (motility by CASA and chromatin damage by sperm chromatin structure assay) with 200 μm. Lipoperoxidation assessed by the thiobarbituric acid reactive substance (TBARS) method increased slightly with 50 μm H(2)O(2) and above. In a second experiment, samples from seven males were submitted to 0 and 200 μm H(2)O(2) for 2 h, triplicating the experiment within each male. Males differed at thawing and regarding their response to incubation and H(2)O(2) presence. We found that the kinematic parameters reflected male-to-male variability, whereas the response of the different males was similar for lipid peroxidation and viability. A multiparametric analysis showed that males grouped differently if samples were assessed after thawing, after incubation without H(2)O(2) or after incubation with H(2)O(2) . Red deer spermatozoa are relatively resilient to H(2)O(2) after thawing, but it seems to be a great male-to-male variability regarding the response to oxidative stress. The acknowledgement of this individual variability might improve the development of optimized sperm work protocols. © 2010 Blackwell Verlag GmbH.

  1. Loss of protein kinase 2 subunit alpha 2 (CK2α') effect ram sperm function after freezing and thawing process.

    Science.gov (United States)

    He, Yuxuan; Li, Hongyan; Wang, Ke; Zhang, Yong; Zhao, Xingxu

    2017-06-01

    Protein kinase 2 subunit alpha 2 (CK2α'), a serine/threonine-selective protein kinase, is associated with sperm apoptosis. However, the presence of CK2α' in ram sperm during the freezing-thawing process has not been previously reported. Thus, this study was conducted to determine the effect of cryopreservation on the association between CK2α' and ram sperm function. Sperm variables, including sperm motility, DNA damage and acrosome integrity, were measured in fresh (F), cooled (CO) and freeze-thawed (FT) sperm. Sperm proteins and total mRNA were extracted form cells of each group, and subjected to western blot and real-time PCR analysis for detection of CK2α' proteins and relative abundance of mRNA. The distribution pattern of CK2α' protein in ram sperm was also monitored in each group using an immunofluorescence technique. The results provided evidence that the freeze-thaw process has an impact on ram sperm variables, and the normalized CK2α' protein and relative abundance of CK2α' mRNA were both significantly less in FT than F sperm. The amount of CK2α' in FT extended seminal plasma was increased as compared with F samples. Furthermore, immunofluorescence revealed that CK2α' was distributed throughout the acrosome of ram sperm. The association of CK2α' with DNA damage and acrosome integrity was confirmed using Pearson's linear correlation. In conclusion, the understanding the molecular effects of cryopreservation on CK2α' in ram sperm could provide insight into methods for improving fertility associated with frozen-thawed ram sperm. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. A comparison of Freeze-Thaw in roads with passive microwave satellite observations from SMAP

    Science.gov (United States)

    Kraatz, S.; Jacobs, J. M.; Miller, H.; Daniel, J.

    2017-12-01

    Freeze-thaw (F/T) timings are relevant to both natural and manmade systems as they impact the global carbon budget, health of natural systems (forests) and the safety of roads and structures. The Soil Moisture Active Passive (SMAP) mission's two L-band radiometer F/T products are obtained at 36 km2 footprint and thus mostly observe the natural environment. Roadway temperature data are available from temperature data probes (TDP), which measure temperature from above the ground to 1.8 m depth below the pavement. Differences in F/T timing between natural (SMAP + in-situ cal/val sites) and engineered (road TDP) sites are investigated. Dates of F/T were estimated using a moving window with a threshold of 0oC. The process was repeated for TDP data for air, road surface and road bottom temperatures. The impact of this work is to explore 1) how TDP data corresponds to the new radiometer based F/T product, 2) differences in F/T between roads and natural sites, 3) whether SMAP F/T leads or lags TDP measurements and 4) the variability of F/T dates based on the temperature measurement depth.

  3. 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

  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. Vegetation controls on carbon, water, and energy dynamics with implications for permafrost thaw

    Science.gov (United States)

    Loranty, M. M.; Berner, L. T.

    2013-12-01

    Changes in ecosystem structure and function characterized by climate induced alterations in vegetation communities will exert strong influence on the fate of permafrost carbon via controls on surface energy partitioning. These controls are likely to occur both directly through changes in ground heat fluxes and indirectly through climate feedbacks associated with changes in albedo and evapotranspiration. Larch forests of northeastern Siberia constitute the largest ecosystem type underlain by continuous permafrost and therefore warrant considerable attention in this regard. Here we report observations of carbon, water, and energy fluxes made using the static chamber method for three understory vegetation communities in a mature northeastern Siberian larch forest. We find that carbon and water fluxes tend to increase in magnitude with NDVI, with carbon fluxes exhibiting net uptake during the growing season in vegetation communities dominated by deciduous shrubs. Communities characterized by a combination of evergreen and deciduous shrubs and mosses, or by lichens we find lower water fluxes and carbon neutrality. In the case of lichens, water fluxes are low while surface and soil temperatures as well as thaw depths are relatively high. These results illustrate the potential for vegetation to influence permafrost dynamics through controls on surface energy partitioning. While our results stem from a relatively small spatial scale, they are a relevant analog for large-scale shifts in arctic and boreal vegetation communities as well as changes in successional dynamics associated with changing disturbance regimes, particularly fire.

  6. 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.

  7. Effect of hyaluronic acid-enriched transfer medium on frozen-thawed embryo transfer outcomes.

    Science.gov (United States)

    Fu, Wei; Yu, Min; Zhang, Xiao-Jin

    2018-04-01

    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 Gynecology.

  8. 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.

  9. 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.

  10. Physically Accurate Soil Freeze-Thaw Processes in a Global Land Surface Scheme

    Science.gov (United States)

    Cuntz, Matthias; Haverd, Vanessa

    2018-01-01

    The model Soil-Litter-Iso (SLI) calculates coupled heat and water transport in soil. It was recently implemented into the Australian land surface model CABLE, which is the land component of the Australian Community Climate and Earth System Simulator (ACCESS). Here we extended SLI to include accurate freeze-thaw processes in the soil and snow. SLI provides thence an implicit solution of the energy and water balances of soil and snow as a standalone model and within CABLE. The enhanced SLI was tested extensively against theoretical formulations, laboratory experiments, field data, and satellite retrievals. The model performed well for all experiments at wide-ranging temporal and spatial scales. SLI melts snow faster at the end of the cold season compared to observations though because there is no subgrid variability within SLI given by the implicit, coupled solution of energy and water. Combined CABLE-SLI shows very realistic dynamics and extent of permafrost on the Northern hemisphere. It illustrated, however, also the limits of possible comparisons between large-scale land surface models and local permafrost observations. CABLE-SLI exhibits the same patterns of snow depth and snow water equivalent on the Northern hemisphere compared to satellite-derived observations but quantitative comparisons depend largely on the given meteorological input fields. Further extension of CABLE-SLI with depth-dependence of soil carbon will allow realistic projections of the development of permafrost and frozen carbon stocks in a changing climate.

  11. 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.

  12. 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.

  13. Evaluating permafrost thaw vulnerabilities and hydrologic impacts in boreal Alaska (USA) watersheds using field data and cryohydrogeologic modeling

    Science.gov (United States)

    Walvoord, M. A.; Voss, C.; Ebel, B. A.; Minsley, B. J.

    2017-12-01

    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.

  14. 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.

  15. Linear disturbances on discontinuous permafrost: implications for thaw-induced changes to land cover and drainage patterns

    International Nuclear Information System (INIS)

    Williams, Tyler J; Quinton, William L; Baltzer, Jennifer L

    2013-01-01

    Within the zone of discontinuous permafrost, linear disturbances such as winter roads and seismic lines severely alter the hydrology, ecology, and ground thermal regime. Continued resource exploration in this environment has created a need to better understand the processes causing permafrost thaw and concomitant changes to the terrain and ground cover, in order to efficiently reduce the environmental impact of future exploration through the development of best management practices. In a peatland 50 km south of Fort Simpson, NWT, permafrost thaw and the resulting ground surface subsidence have produced water-logged linear disturbances that appear not to be regenerating permafrost, and in many cases have altered the land cover type to resemble that of a wetland bog or fen. Subsidence alters the hydrology of plateaus, developing a fill and spill drainage pattern that allows some disturbances to be hydrologically connected with adjacent wetlands via surface flow paths during periods of high water availability. The degree of initial disturbance is an important control on the extent of permafrost thaw and thus the overall potential recovery of the linear disturbance. Low impact techniques that minimize ground surface disturbance and maintain original surface topography by eliminating windrows are needed to minimize the impact of these linear disturbances. (letter)

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Acrosin release and acrosin activity during incubation in capacitating media using fresh and frozen-thawed dog sperm

    Directory of Open Access Journals (Sweden)

    Mónica de los Reyes

    2011-01-01

    Full Text Available We evaluated the effect of time and temperature on acrosin release from the acrosomal cap and the activity of this enzyme during in vitro capacitation in fresh and frozen/thawed dog sperm. Sperm-rich fractions of six ejaculates from three dogs were processed as fresh and frozen samples. Each sperm sample was incubated in canine capacitation medium (CCM for 0, 1, 2 and 3 h at 20°C and at 37°C. After incubation, the samples were assessed by the indirect immunofluorescent staining technique. The probability of having unlabeled sperm (PUS, indicating acrosin loss, was modelled by a binomial distribution using logistic regression. There was a linear relationship between PUS and time at both temperatures (p<0.001; however, a major percentage of unlabeled sperm was observed in frozen/thawed samples soon after incubation, indicating that the release of acrosin was affected by capacitation time, mainly in frozen samples. Temperature influenced acrosin release only in cryopreserved sperm (p<0.05. Acrosin activity was measured by digestion halos on slides coated with gelatin-substrate film during each time period; a significant increase in the number of large halos was observed in fresh samples throughout the experiment, whereas frozen/thawed sperm showed a decreased rate of halo diameters during culture. Thus, there appears to differences between fresh and frozen dog sperm in terms of acrosin release and the level of acrosin activity in the course of in vitro capacitation.

  1. Femoral curvature in Neanderthals and modern humans: a 3D geometric morphometric analysis.

    Science.gov (United States)

    De Groote, Isabelle

    2011-05-01

    Since their discovery, Neanderthals have been described as having a marked degree of anteroposterior curvature of the femoral shaft. Although initially believed to be pathological, subsequent discoveries of Neanderthal remains lead femoral curvature to be considered as a derived Neanderthal feature. A recent study on Neanderthals and middle and early Upper Palaeolithic modern humans found no differences in femoral curvature, but did not consider size-corrected curvature. Therefore, the objectives of this study were to use 3D morphometric landmark and semi-landmark analysis to quantify relative femoral curvature in Neanderthals, Upper Palaeolithic and recent modern humans, and to compare adult bone curvature as part of the overall femoral morphology among these populations. Comparisons among populations were made using geometric morphometrics (3D landmarks) and standard multivariate methods. Comparative material involved all available complete femora from Neanderthal and Upper Palaeolithic modern human, archaeological (Mesolithic, Neolithic, Medieval) and recent human populations representing a wide geographical and lifestyle range. There are significant differences in the anatomy of the femur between Neanderthals and modern humans. Neanderthals have more curved femora than modern humans. Early modern humans are most similar to recent modern humans in their anatomy. Femoral curvature is a good indicator of activity level and habitual loading of the lower limb, indicating higher activity levels in Neanderthals than modern humans. These differences contradict robusticity studies and the archaeological record, and would suggest that femoral morphology, and curvature in particular, in Neanderthals may not be explained by adult behavior alone and could be the result of genetic drift, natural selection or differences in behavior during ontogeny. Copyright © 2010 Elsevier Ltd. All rights reserved.

  2. HCG administration after endogenous LH rise negatively influences pregnancy rate in modified natural cycle for frozen-thawed euploid blastocyst transfer: a pilot study.

    Science.gov (United States)

    Litwicka, Katarzyna; Mencacci, Cecilia; Arrivi, Cristiana; Varricchio, Maria Teresa; Caragia, Alina; Minasi, Maria Giulia; Greco, Ermanno

    2017-11-17

    The aim of the present study was to evaluate whether in a modified natural cycle (modified-NC) for a frozen-thawed single euploid blastocyst transfer, a critical LH value, above which human chorionic gonadotropin (hCG) administration should be avoided, may be defined. One hundred and sixty-seven patients underwent modified natural cycle in order to transfer a single frozen-thawed euploid blastocyst. All embryos were obtained by intracytoplasmic sperm injection and were biopsied at the blastocyst stage and analyzed by means of array comparative genomic hybridization (aCGH). Ovulation was induced using 10.000 IU hCG when the mean follicle diameter was at least of 17 mm, independently from LH values. The primary end points were the hCG-positive test and clinical pregnancy. The interim analysis showed that LH value ≥ 13 mIU/ml on the day of hCG injection may negatively influence the clinical results, suggesting that in this condition, it should be advisable waiting for spontaneous ovulation. Among patients who received hCG for ovulation induction, the hCG-positive test and clinical pregnancy rates in modified-NC were significantly lower in cycles with LH ≥ 13 mIU/ml in respect to those with LH hCG administration led to significantly lower rates of hCG-positive test (45.4 vs 74.5% in hCG administration and spontaneous ovulation groups, respectively) and clinical pregnancy (36.4 vs 64.7% in hCG administration and spontaneous ovulation groups, respectively). The baseline patient characteristics were comparable in all groups. The findings of this study highlight that LH elevation ≥ 13 mIU/ml prior to hCG administration may negatively affect clinical pregnancy rates in modified-NC for single euploid blastocyst transfer. The LH determination should be routinely performed during follicular monitoring. In the presence of LH level ≥ 13 mIU/ml, hCG administration should be avoided, and the embryo transfer should be planned only after spontaneous

  3. 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=0.05842m 2 /°C·day; R 2 =0.63) is in agreement with other permafrost environments, since frozen index (F>0.67) and MAAT (<-2°C) denote a continuous permafrost existence in the area. All these characteristics provided the basis for further comparative analyses between others nearby CALM sites. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. 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

  5. Pleistocene Permafrost Thawing History of Alaska, the Yukon, and the Northwest Territories from U-Th Dating of Cave Speleothems

    Science.gov (United States)

    Biller, N.; Shakun, J. D.; McGee, D.; Hardt, B. F.; Ford, D.; Lauriol, B.

    2015-12-01

    Permafrost, or permanently frozen ground, is widespread in the Arctic and contains twice as much carbon as the atmosphere in the form of frozen organic matter. This carbon may be vulnerable to thaw and release to the atmosphere as methane under a warming climate, making permafrost thaw one of the potentially most significant amplifying feedbacks to anthropogenic warming. Nonetheless, permafrost can be slow to respond to warming, the short instrumental record may not adequately capture long-term trends, and the modest temperature changes of the past few millennia provide poor analogues to understand the possibility of crossing climate thresholds in the next century or beyond. One way to address this problem is to assess the stability of permafrost during previous interglacial periods of varying levels of warmth, which provide natural experiments to examine the Arctic's sensitivity to warming. Cave speleothems in the Arctic are relics of past periods of thaw that enabled meteoric water to seep into caves and deposit calcite. We employed uranium-thorium (U-Th) dating to constrain the chronology and extent of permafrost thaw in the North American Arctic during the past 600,000 years. We sampled caves from a range of permafrost zones and latitudes, including the Fishing Branch Territorial Park, Yukon (66.5°N, continuous permafrost), White Mountains National Recreation Area, Alaska (65°N, discontinuous permafrost), Yukon-Charley Rivers National Preserve, Alaska (64.5°N, discontinuous permafrost), and Nahanni National Park Reserve, Northwest Territories (62°N, discontinuous permafrost). Thirty-five samples from 30 speleothems have been analyzed at this point, with 23 samples lying beyond the U-Th dating range, and finite ages tending to cluster near Marine Isotope Stage 11 (MIS 11) within uncertainty, as well as perhaps MIS 9, 13, and 15. This preliminary dataset, coupled with a similar study in Siberia (Vaks et al., 2013), is thus suggestive of an episode of

  6. 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

  7. 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

  8. Modified hMG stimulated: an effective option in endometrial preparation for frozen-thawed embryo transfer in patients with normal menstrual cycles.

    Science.gov (United States)

    Huang, Pinxiu; Wei, Lihong; Li, Xinlin; Lin, Zhong

    2018-04-20

    To evaluate the clinical efficacy of modified human menopausal gonadotropin (hMG) stimulated, hormone replacement therapy (HRT), natural cycling and letrozole ovulation induction during endometrial preparation for frozen-thawed embryo transfer (FET) in patients with normal menstrual cycles. This retrospective analysis included a total of 5070 cycles of patients with normal menstrual patterns who underwent FET between October 2009 and September 2015. The patients were divided into four groups according to the method of endometrial preparation for FET: 1838 cycles were natural, 1666 underwent HRT, 340 underwent letrozole ovulation induction and 1226 underwent modified hMG stimulated. Reproduction-related clinical outcomes in the four groups were compared. The clinical pregnancy rates and live birth rates of patients in the modified hMG stimulated group were significantly higher than that in the other groups p .05). Modified hMG stimulated resulted in a higher pregnancy rate compared to the other treatment groups. Therefore, modified hMG stimulated may be an effective option in endometrial preparation for FET in patients with normal menstrual cycles.

  9. Variety, State and Origin of Drained Thaw Lake Basins in West-Siberian North

    Science.gov (United States)

    Kirpotin, S.; Polishchuk, Y.; Bryksina, N.; Sugaipova, A.; Pokrovsky, O.; Shirokova, L.; Kouraev, A.; Zakharova, E.; Kolmakova, M.; Dupre, B.

    2009-04-01

    Drained thaw lake basins in Western Siberia have a local name "khasyreis" [1]. Khasyreis as well as lakes, ponds and frozen mounds are invariable element of sub-arctic frozen peat bogs - palsas and tundra landscapes. In some areas of West-Siberian sub-arctic khasyreis occupy up to 40-50% of total lake area. Sometimes their concentration is so high that we call such places ‘khasyrei's fields". Khasyreis are part of the natural cycle of palsa complex development [1], but their origin is not continuous and uniform in time and, according to our opinion, there were periods of more intensive lake drainage and khasyrei development accordingly. These times were corresponding with epochs of climatic warming and today we have faced with one of them. So, last years this process was sufficiently activated in the south part of West-Siberian sub-arctic [2]. It was discovered that in the zone of continuous permafrost thermokarst lakes have expanded their areas by about 10-12%, but in the zone of discontinuous permafrost the process of their drainage prevails. These features are connected with the thickness of peat layers which gradually decreases to the North, and thus have reduced the opportunity for lake drainage in northern areas. The most typical way of khasyrei origin is their drainage to the bigger lakes which are always situated on the lower levels and works as a collecting funnels providing drainage of smaller lakes. The lower level of the big lake appeared when the lake takes a critical mass of water enough for subsidence of the lake bottom due to the melting of underlaying rocks [2]. Another one way of lake drainage is the lake intercept by any river. Lake drainage to the subsurface (underlaying rocks) as some authors think [3, 4] is not possible in Western Siberia, because the thickness of permafrost is at list 500 m here being safe confining bed. We mark out few stages of khasyrei development: freshly drained, young, mature and old. This row reflects stages of

  10. 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.

  11. Assimilation of Freeze-Thaw Observations into the NASA Catchment Land Surface Model

    Science.gov (United States)

    Farhadi, L.; Reichle, R. H.; De Lannoy, G. J.; Kimball, J. S.

    2013-12-01

    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 net primary productivity at the land surface. To support the level 4 soil moisture and carbon products (value-added, i.e. using a combination of remote sensing data and modeling) for the planned NASA Soil Moisture Active Passive (SMAP) mission, an F/T assimilation algorithm is developed 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. A rule-based approach that incorporates model and observational errors is developed and used for assimilating the categorical F/T measurements into the land surface model (F/T analysis). An Observing System Simulation Experiment is conducted using synthetically generated measurements of the F/T state for a region in North America (90-110oW longitude, 45-55oN latitude). The synthetic 'truth' is generated using the NASA Catchment land surface model forced with surface meteorological fields from the Modern-Era Retrospective Reanalysis for Research and Applications (MERRA). To generate synthetic measurements, the true categorical F/T state is corrupted with a prescribed amount of F/T classification error. The assimilation experiment employs the same Catchment model except that forcing errors (relative to truth) are introduced via the application of meteorological forcing fields from the Global Land Data Assimilation System (GLDAS). The effect of the F/T analysis and classification error on land surface temperature and soil temperature predictions is examined in this research.

  12. 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.

  13. 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.

  14. 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...

  15. Sealed osteons in animals and humans: low prevalence and lack of relationship with age.

    Science.gov (United States)

    Skedros, John G; Henrie, Tanner R; Doutré, Madison S; Bloebaum, Roy D

    2018-05-01

    Sealed osteons are unusual variants of secondary osteons that have received little attention, especially in non-human bones. Sealed osteons are characterized by central canals that are plugged with bone tissue. As with other variants of secondary osteons (e.g. drifting, dumbbell, multi-canal), understanding how and why sealed osteons form can shed light on the mechanisms that regulate normal bone remodeling and how this process can be perturbed with aging and some diseases. In a recent microscopic evaluation of human tibiae obtained after traumatic amputations, 4-5% of the osteons were sealed. It is suggested that this high prevalence reflects occasional localized microscopic ischemia from normal osteonal remodeling; hence sealed osteons are implicated in human skeletal fragility. Therefore, osteon prevalence would be expected to correlate with the bone remodeling seen with aging; for example, showing positive relationships between sealed osteons and the population density of typical secondary osteons (OPD). We evaluated the prevalence of partially sealed (80-99% sealed) and fully sealed osteons with respect to age and variations in OPD in 10 adult human femora (34-71 years) and in various non-human appendicular bones of mature animals that were not of advanced age, including deer calcanei, equine radii and equine third metacarpals. An additional sample of 10 bilateral human femora with unilateral non-cemented total hip replacements (F,+HR) and non-implanted contralateral femora (F,-HR) were evaluated (10 patients; 52-94 years). In non-human bones, sealed + partially sealed osteons were rare (~0.1%) even when having relatively high OPD. When considering sealed + partially sealed osteons in femora from patients without any HR, results showed that 1.6% of the osteons were sealed or partially sealed, which was much lower than anticipated, but this is 10- to 20-fold more than in any of the non-human bones. Additionally, in all bones, sealed + partially sealed

  16. Feasibility of refreezing human spermatozoa through the technique of liquid nitrogen vapor

    Directory of Open Access Journals (Sweden)

    Sidney Verza Jr

    2004-12-01

    Full Text Available OBJECTIVE: To assess the feasibility of refreezing human semen using the technique of liquid nitrogen vapor with static phases. MATERIALS AND METHODS: Twenty samples from 16 subjects who required disposal of their cryopreserved semen were thawed, corresponding to 6 cancer patients and 10 participants in the assisted reproduction (AR program. Samples were refrozen using the technique of liquid nitrogen vapor with static phases, identical to the one used for the initial freezing, and thawed again after 72 hours. We assessed the concentration of motile spermatozoa, total and progressive percent motility and spermatic vitality, according to criteria of the World Health Organization (WHO, as well as spermatic morphology according to the strict Kruger criterion, after the first and after the second thawing. RESULTS: We observed a significant decrease in all the parameters evaluated between the first and the second thawing. Median values for the concentration of motile spermatozoa decreased from 2.0x10(6/mL to 0.1x10(6/mL (p < 0.01; total percent motility from 42% to 22.5% (p < 0.01; progressive percent motility from 34% to 9.5% (p < 0.01; vitality from 45% to 20% (p < 0.01; and morphology from 5% to 5% (p = 0.03. There was no significant difference in the spermatic parameters between the cancer and assisted reproduction groups, both after the first and after the second thawing. We observed that in 100% of cases there was retrieval of motile spermatozoa after the second thawing. CONCLUSIONS: Refreezing of human semen by the technique of liquid nitrogen vapor allows the retrieval of viable spermatozoa after thawing.

  17. 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.

  18. Tree density and permafrost thaw depth influence water limitations on stomatal conductance in Siberian Arctic boreal forests

    Science.gov (United States)

    Kropp, H.; Loranty, M. M.; Natali, S.; Kholodov, A. L.; Alexander, H. D.; Zimov, N.

    2017-12-01

    Boreal forests may experience increased water stress under global climate change as rising air temperatures increase evaporative demand and decrease soil moisture. Increases in plant water stress can decrease stomatal conductance, and ultimately, decrease primary productivity. A large portion of boreal forests are located in Siberia, and are dominated by deciduous needleleaf trees, Larix spp. We investigated the variability and drivers of canopy stomatal conductance in upland Larix stands with different stand density that arose from differing fire severity. Our measurements focus on an open canopy stand with low tree density and deep permafrost thaw depth, and a closed canopy stand with high tree density and shallow permafrost thaw depth. We measured canopy stomatal conductance, soil moisture, and micrometeorological variables. Our results demonstrate that canopy stomatal conductance was significantly lower in the closed canopy stand with a significantly higher sensitivity to increases in atmospheric evaporative demand. Canopy stomatal conductance in both stands was tightly coupled to precipitation that occurred over the previous week; however, the closed canopy stand showed a significantly greater sensitivity to increases in precipitation compared to the open canopy stand. Differences in access to deep versus shallow soil moisture and the physical characteristics of the soil profile likely contribute to differences in sensitivity to precipitation between the two stands. Our results indicate that Larix primary productivity may be highly sensitive to changes in evaporative demand and soil moisture that can result of global climate change. However, the effect of increasing air temperatures and changes in precipitation will differ significantly depending on stand density, thaw depth, and the hydraulic characteristics of the soil profile.

  19. 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.

  20. Improved Post-Thaw Function and Epigenetic Changes in Mesenchymal Stromal Cells Cryopreserved Using Multicomponent Osmolyte Solutions.

    Science.gov (United States)

    Pollock, Kathryn; Samsonraj, Rebekah M; Dudakovic, Amel; Thaler, Roman; Stumbras, Aron; McKenna, David H; Dosa, Peter I; van Wijnen, Andre J; Hubel, Allison

    2017-06-01

    Current methods for freezing mesenchymal stromal cells (MSCs) result in poor post-thaw function, which limits the clinical utility of these cells. This investigation develops a novel approach to preserve MSCs using combinations of sugars, sugar alcohols, and small-molecule additives. MSCs frozen using these solutions exhibit improved post-thaw attachment and a more normal alignment of the actin cytoskeleton compared to cells exposed to dimethylsulfoxide (DMSO). Osteogenic and chondrogenic differentiation assays show that cells retain their mesenchymal lineage properties. Genomic analysis indicates that the different freezing media evaluated have different effects on the levels of DNA hydroxymethylation, which are a principal epigenetic mark and a key step in the demethylation of CpG doublets. RNA sequencing and quantitative real time-polymerase chain reaction validation demonstrate that transcripts for distinct classes of cytoprotective genes, as well as genes related to extracellular matrix structure and growth factor/receptor signaling are upregulated in experimental freezing solutions compared to DMSO. For example, the osmotic regulator galanin, the antiapoptotic marker B cell lymphoma 2, as well as the cell surface adhesion molecules CD106 (vascular cell adhesion molecule 1) and CD54 (intracellular adhesion molecule 1) are all elevated in DMSO-free solutions. These studies validate the concept that DMSO-free solutions improve post-thaw biological functions and are viable alternatives for freezing MSCs. These novel solutions promote expression of cytoprotective genes, modulate the CpG epigenome, and retain the differentiation ability of MSCs, suggesting that osmolyte-based freezing solutions may provide a new paradigm for therapeutic cell preservation.

  1. 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.

  2. 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

    Effects were studied of various technological parameters and fishing ground on quality attributes of thawed, chilled cod fillets stored in modified atmosphere packaging Frozen fillets of Baltic Sea and Barents Sea cod, representing two commercial fishing grounds, were used as raw material....... The parameters investigated were: (1) packaging in modified atmosphere during frozen storage, (2)frozen storage period and temperature, (3),fishing ground and chill storage temperature, together with (4) the addition of trimethylamine oxide (TMAO) and sodium chloride (NaCl) to cod fillets before freezing...

  3. 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 and.......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....

  4. 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

  5. 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 (CH 4 ) emissions. Here, we quantify the thaw-induced increase in CH 4 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 (CO 2 ) exchange. Using nested wetland and landscape eddy covariance net CH 4 flux measurements in combination with flux footprint modeling, we find that landscape CH 4 emissions increase with increasing wetland-to-forest ratio. Landscape CH 4 emissions are most sensitive to this ratio during peak emission periods, when wetland soils are up to 10 °C warmer than forest soils. The cumulative growing season (May-October) wetland CH 4 emission of ~13 g CH 4  m -2 is the dominating contribution to the landscape CH 4 emission of ~7 g CH 4  m -2 . In contrast, forest contributions to landscape CH 4 emissions appear to be negligible. The rapid wetland expansion of 0.26 ± 0.05% yr -1 in this region causes an estimated growing season increase of 0.034 ± 0.007 g CH 4  m -2  yr -1 in landscape CH 4 emissions. A long-term net CO 2 uptake of >200 g CO 2  m -2  yr -1 is required to offset the positive radiative forcing of increasing CH 4 emissions until the end of the 21st century as indicated by an atmospheric CH 4 and CO 2 concentration model. However, long-term apparent carbon accumulation rates in similar boreal forest-wetland landscapes and eddy covariance landscape net CO 2 flux measurements suggest a long-term net CO 2 uptake between 49 and 157 g CO 2  m -2  yr -1 . Thus, thaw-induced CH 4 emission increases likely exert a positive net radiative greenhouse gas

  6. Multi-channel ground-penetrating radar to explore spatial variations in thaw depth and moisture content in the active layer of a permafrost site

    Directory of Open Access Journals (Sweden)

    U. Wollschläger

    2010-08-01

    Full Text Available Multi-channel ground-penetrating radar (GPR was applied at a permafrost site on the Tibetan Plateau to investigate the influence of surface properties and soil texture on the late-summer thaw depth and average soil moisture content of the active layer. Measurements were conducted on an approximately 85 × 60 m2 sized area with surface and soil textural properties that ranged from medium to coarse textured bare soil to finer textured, sparsely vegetated areas covered with fine, wind blown sand, and it included the bed of a gravel road. The survey allowed a clear differentiation of the various units. It showed (i a shallow thaw depth and low average soil moisture content below the sand-covered, vegetated area, (ii an intermediate thaw depth and high average soil moisture content along the gravel road, and (iii an intermediate to deep thaw depth and low to intermediate average soil moisture content in the bare soil terrain. From our measurements, we found hypotheses for the permafrost processes at this site leading to the observed late-summer thaw depth and soil moisture conditions. The study clearly indicates the complicated interactions between surface and subsurface state variables and processes in this environment. Multi-channel GPR is an operational technology to efficiently study such a system at scales varying from a few meters to a few kilometers.

  7. EFFECT OF THE ADDITION OF SEMINAL PLASMA, VITAMIN E AND INCUBATION TIME ON POST-THAWED SPERM VIABILITY IN BOAR SEMEN

    Directory of Open Access Journals (Sweden)

    Alba G C Pech-Sansores

    2011-09-01

    Full Text Available The objective of the study was to evaluate the effect of seminal plasma (SP, vitamin E (VE, and incubation time on sperm viability of post-thawed boar semen. Thirty six ejaculates were used and allocated to four treatments: T1, semen + BTS (Belstville Thawing Solution + 10% SP; T2, semen + BTS + 200μg/ml VE; T3, semen + BTS + 10% SP + 200μg/ml VE; T4, semen + BTS (control. Motility (MOT, intact acrosomes (IA, membrane integrity (MI and mitochondrial activity (MA were evaluated, at 0 and 30 min after thawing. A split plot design was used and the data analyzed using a mixed model analysis of variance. There was a significant effect of SP and VE on IA and MI (P0.05. There was significant effect of incubation time on MOT (21.3 and 27.9% and IA (46.0 and 36.0%, at 0 and 30 min post-thawing (P <0.05. It is concluded that the vitamin E, seminal plasma or the combination of both, affected the thawed sperm traits here studied. Incubation time increased motility and intact acrosome percentage but did not affect the membrane integrity and mitochondrial activity.

  8. The effect of two pre-cryopreservation single layer colloidal centrifugation protocols in combination with different freezing extenders on the fragmentation dynamics of thawed equine sperm DNA.

    Science.gov (United States)

    Gutiérrez-Cepeda, Luna; Fernández, Alvaro; Crespo, Francisco; Ramírez, Miguel Ángel; Gosálvez, Jaime; Serres, Consuelo

    2012-12-05

    Variability among stallions in terms of semen cryopreservation quality renders it difficult to arrive at a standardized cryopreservation method. Different extenders and processing techniques (such us colloidal centrifugation) are used in order to optimize post-thaw sperm quality. Sperm chromatin integrity analysis is an effective tool for assessing such quality. The aim of the present study was to compare the effect of two single layer colloidal centrifugation protocols (prior to cryopreservation) in combination with three commercial freezing extenders on the post-thaw chromatin integrity of equine sperm samples at different post-thaw incubation (37°C) times (i.e., their DNA fragmentation dynamics). Post-thaw DNA fragmentation levels in semen samples subjected to either of the colloidal centrifugation protocols were significantly lower (pcentrifugation. The use of InraFreeze® extender was associated with significantly less DNA fragmentation than the use of Botu-Crio® extender at 6 h of incubation, and than the use of either Botu-Crio® or Gent® extender at 24 h of incubation (pcentrifugation performed with extended or raw semen prior to cryopreservation reduces DNA fragmentation during the first four hours after thawing. Further studies are needed to determine the influence of freezing extenders on equine sperm DNA fragmentation dynamics.

  9. A Passive Microwave L-Band Boreal Forest Freeze/Thaw and Vegetation Phenology Study

    Science.gov (United States)

    Roy, A.; Sonnentag, O.; Pappas, C.; Mavrovic, A.; Royer, A.; Berg, A. A.; Rowlandson, T. L.; Lemay, J.; Helgason, W.; Barr, A.; Black, T. A.; Derksen, C.; Toose, P.

    2016-12-01

    The boreal forest is the second largest land biome in the world and thus plays a major role in the global and regional climate systems. The extent, timing and duration of seasonal freeze/thaw (F/T) state influences vegetation developmental stages (phenology) and, consequently, constitute an important control on how boreal forest ecosystems exchange carbon, water and energy with the atmosphere. The effective retrieval of seasonal F/T state from L-Band radiometry was demonstrated using satellite mission. However, disentangling the seasonally differing contributions from forest overstory and understory vegetation, and the soil surface to the satellite signal remains challenging. Here we present initial results from a radiometer field campaign to improve our understanding of the L-Band derived boreal forest F/T signal and vegetation phenology. Two L-Band surface-based radiometers (SBR) are installed on a micrometeorological tower at the Southern Old Black Spruce site in central Saskatchewan over the 2016-2017 F/T season. One radiometer unit is installed on the flux tower so it views forest including all overstory and understory vegetation and the moss-covered ground surface. A second radiometer unit is installed within the boreal forest overstory, viewing the understory and the ground surface. The objectives of our study are (i) to disentangle the L-Band F/T signal contribution of boreal forest overstory from the understory and ground surface, (ii) to link the L-Band F/T signal to related boreal forest structural and functional characteristics, and (iii) to investigate the use of the L-Band signal to characterize boreal forest carbon, water and energy fluxes. The SBR observations above and within the forest canopy are used to retrieve the transmissivity (γ) and the scattering albedo (ω), two parameters that describe the emission of the forest canopy though the F/T season. These two forest parameters are compared with boreal forest structural and functional

  10. Percentage of ubiquitinated spermatozoa does not correlate with fertilizing capacity of thawed bovine semen.

    Science.gov (United States)

    Rodríguez-Lozano, I; Ávalos-Rodríguez, A; Castillo-Juárez, H; Borderas-Tordesillas, F; Roa-Vidal, J J; Rosales-Torres, A M

    2014-02-01

    In the spermatozoa of some species, the ubiquitin-proteasome system detects altered proteins and tags them for elimination by the proteasome. In some species' ejaculates, a high proportion of ubiquitinated spermatozoa (i.e. those having ubiquitin bound to the altered or damaged membrane proteins) has been related to infertility. The aim of this study was to assess whether the percentage of ubiquitinated spermatozoa relates to fertility of dairy bulls and whether ubiquitination increases during protein remodelling that occurs during in vitro spermatic capacitation. Thirty-two frozen semen straws from four high-fertility (ReproMax(®) ) and four normal-fertility (Normal) Holstein-Friesian sires were evaluated. Ubiquitinated and capacitated spermatozoa were quantified by sperm ubiquitin tag immunoassay and chlortetracycline stain, respectively. Fertilizing capacity of sires was assessed by in vitro fertilization. No differences were found between Normal and ReproMax(®) sires with regard to the observed percentage of ubiquitinated spermatozoa (42.97 ± 3.69% and 49.68 ± 9.27%, respectively; p > 0.05). Additionally, no differences were found in the percentage of ubiquitinated spermatozoa as a consequence of spermatic capacitation in either Normal (42.97 ± 3.69% before capacitation vs 44.67 ± 7.5% after; p > 0.05) or ReproMax(®) sires (49.68 ± 9.27% before vs 45.05 ± 7.51% after; p > 0.05). The percentage of ubiquitinated spermatozoa in a thawed sperm samples did not correlate with its in vitro fertilizing capacity; thus, this assay does not prove useful to detect in vivo fertility differences between sires. Additionally, protein degradation occurring during remodelling of the spermatozoon plasma membrane during the capacitation process does not seem to involve the ubiquitin-proteasome system. © 2013 Blackwell Verlag GmbH.

  11. Cellular Biophysics During Freezing of Rat and Mouse Sperm Predicts Post-thaw Motility1

    Science.gov (United States)

    Hagiwara, Mie; Choi, Jeung Hwan; Devireddy, Ramachandra V.; Roberts, Kenneth P.; Wolkers, Willem F.; Makhlouf, Antoine; Bischof, John C.

    2009-01-01

    Though cryopreservation of mouse sperm yields good survival and motility after thawing, cryopreservation of rat sperm remains a challenge. This study was designed to evaluate the biophysics (membrane permeability) of rat in comparison to mouse to better understand the cooling rate response that contributes to cryopreservation success or failure in these two sperm types. In order to extract subzero membrane hydraulic permeability in the presence of ice, a differential scanning calorimeter (DSC) method was used. By analyzing rat and mouse sperm frozen at 5°C/min and 20°C/min, heat release signatures characteristic of each sperm type were obtained and correlated to cellular dehydration. The dehydration response was then fit to a model of cellular water transport (dehydration) by adjusting cell-specific biophysical (membrane hydraulic permeability) parameters Lpg and ELp. A “combined fit” (to 5°C/min and 20°C/min data) for rat sperm in Biggers-Whitten-Whittingham media yielded Lpg = 0.007 μm min−1 atm−1 and ELp = 17.8 kcal/mol, and in egg yolk cryopreservation media yielded Lpg = 0.005 μm min−1 atm−1 and ELp = 14.3 kcal/mol. These parameters, especially the activation energy, were found to be lower than previously published parameters for mouse sperm. In addition, the biophysical responses in mouse and rat sperm were shown to depend on the constituents of the cryopreservation media, in particular egg yolk and glycerol. Using these parameters, optimal cooling rates for cryopreservation were predicted for each sperm based on a criteria of 5%–15% normalized cell water at −30°C during freezing in cryopreservation media. These predicted rates range from 53°C/min to 70°C/min and from 28°C/min to 36°C/min in rat and mouse, respectively. These predictions were validated by comparison to experimentally determined cryopreservation outcomes, in this case based on motility. Maximum motility was obtained with freezing rates between 50°C/min and 80

  12. Cellular biophysics during freezing of rat and mouse sperm predicts post-thaw motility.

    Science.gov (United States)

    Hagiwara, Mie; Choi, Jeung Hwan; Devireddy, Ramachandra V; Roberts, Kenneth P; Wolkers, Willem F; Makhlouf, Antoine; Bischof, John C

    2009-10-01

    Though cryopreservation of mouse sperm yields good survival and motility after thawing, cryopreservation of rat sperm remains a challenge. This study was designed to evaluate the biophysics (membrane permeability) of rat in comparison to mouse to better understand the cooling rate response that contributes to cryopreservation success or failure in these two sperm types. In order to extract subzero membrane hydraulic permeability in the presence of ice, a differential scanning calorimeter (DSC) method was used. By analyzing rat and mouse sperm frozen at 5 degrees C/min and 20 degrees C/min, heat release signatures characteristic of each sperm type were obtained and correlated to cellular dehydration. The dehydration response was then fit to a model of cellular water transport (dehydration) by adjusting cell-specific biophysical (membrane hydraulic permeability) parameters L(pg) and E(Lp). A "combined fit" (to 5 degrees C/min and 20 degrees C/min data) for rat sperm in Biggers-Whitten-Whittingham media yielded L(pg) = 0.007 microm min(-1) atm(-1) and E(Lp) = 17.8 kcal/mol, and in egg yolk cryopreservation media yielded L(pg) = 0.005 microm min(-1) atm(-1) and E(Lp) = 14.3 kcal/mol. These parameters, especially the activation energy, were found to be lower than previously published parameters for mouse sperm. In addition, the biophysical responses in mouse and rat sperm were shown to depend on the constituents of the cryopreservation media, in particular egg yolk and glycerol. Using these parameters, optimal cooling rates for cryopreservation were predicted for each sperm based on a criteria of 5%-15% normalized cell water at -30 degrees C during freezing in cryopreservation media. These predicted rates range from 53 degrees C/min to 70 degrees C/min and from 28 degrees C/min to 36 degrees C/min in rat and mouse, respectively. These predictions were validated by comparison to experimentally determined cryopreservation outcomes, in this case based on motility. Maximum

  13. A combined effect of freeze--thaw cycles and polymer concentration on the structure and mechanical properties of transparent PVA gels.

    Science.gov (United States)

    Gupta, Siddhi; Goswami, Sudipta; Sinha, Arvind

    2012-02-01

    Transparent poly(vinyl alcohol) (PVA) hydrogel films, derived from aqueous solutions of varying concentration, were synthesized by the cyclic freeze-thaw method (0°-37 °C). This study demonstrates a variation in the transparency, degree of crystallinity, wettability, swelling and mechanical properties of the hydrogels as a function of the solution concentration and the number of freeze-thaw cycles for a given average molecular weight (95,000 Da). The study manifests a strong control of the number of freeze-thaw cycles on the structure-property correlations of the synthesized transparent PVA hydrogels, revealing the possibility of obtaining a window of structural and process parameters for the physically cross-linked hydrogels, making them suitable for cell-gel interactions.

  14. Evaluation of motility, membrane status and DNA integrity of frozen-thawed bottlenose dolphin (Tursiops truncatus) spermatozoa after sex-sorting and recryopreservation.

    Science.gov (United States)

    Montano, G A; Kraemer, D C; Love, C C; Robeck, T R; O'Brien, J K

    2012-06-01

    Artificial insemination (AI) with sex-sorted frozen-thawed spermatozoa has led to enhanced management of ex situ bottlenose dolphin populations. Extended distance of animals from the sorting facility can be overcome by the use of frozen-thawed, sorted and recryopreserved spermatozoa. Although one bottlenose dolphin calf had been born using sexed frozen-thawed spermatozoa derived from frozen semen, a critical evaluation of in vitro sperm quality is needed to justify the routine use of such samples in AI programs. Sperm motility parameters and plasma membrane integrity were influenced by stage of the sex-sorting process, sperm type (non-sorted and sorted) and freezing method (straw and directional) (P0.05) at 24 h. The viability of sorted spermatozoa was higher (Pdolphin spermatozoa undergoing cryopreservation, sorting and recryopreservation are of adequate quality for use in AI.

  15. Optimized Production of Vanillin from Green Vanilla Pods by Enzyme-Assisted Extraction Combined with Pre-Freezing and Thawing

    Directory of Open Access Journals (Sweden)

    Yanjun Zhang

    2014-02-01

    Full Text Available Production of vanillin from natural green vanilla pods was carried out by enzyme-assisted extraction combined with pre-freezing and thawing. In the first step the green vanilla pods were pre-frozen and then thawed to destroy cellular compartmentation. In the second step pectinase from Aspergillus niger was used to hydrolyze the pectin between the glucovanillin substrate and β-glucosidase. Four main variables, including enzyme amount, reaction temperature, time and pH, which were of significance for the vanillin content were studied and a central composite design (CCD based on the results of a single-factor tests was used. Response surface methodology based on CCD was employed to optimize the combination of enzyme amount, reaction temperature, time, and pH for maximum vanillin production. This resulted in the optimal condition in regards of the enzyme amount, reaction temperature, time, and pH at 84.2 mg, 49.5 °C, 7.1 h, and 4.2, respectively. Under the optimal condition, the experimental yield of vanillin was 4.63% ± 0.11% (dwb, which was in good agreement with the value predicted by the model. Compared to the traditional curing process (1.98% and viscozyme extract (2.36%, the optimized method for the vanillin production significantly increased the yield by 133.85% and 96%, respectively.

  16. Optimized production of vanillin from green vanilla pods by enzyme-assisted extraction combined with pre-freezing and thawing.

    Science.gov (United States)

    Zhang, Yanjun; Mo, Limei; Chen, Feng; Lu, Minquan; Dong, Wenjiang; Wang, Qinghuang; Xu, Fei; Gu, Fenglin

    2014-02-19

    Production of vanillin from natural green vanilla pods was carried out by enzyme-assisted extraction combined with pre-freezing and thawing. In the first step the green vanilla pods were pre-frozen and then thawed to destroy cellular compartmentation. In the second step pectinase from Aspergillus niger was used to hydrolyze the pectin between the glucovanillin substrate and β-glucosidase. Four main variables, including enzyme amount, reaction temperature, time and pH, which were of significance for the vanillin content were studied and a central composite design (CCD) based on the results of a single-factor tests was used. Response surface methodology based on CCD was employed to optimize the combination of enzyme amount, reaction temperature, time, and pH for maximum vanillin production. This resulted in the optimal condition in regards of the enzyme amount, reaction temperature, time, and pH at 84.2 mg, 49.5 °C, 7.1 h, and 4.2, respectively. Under the optimal condition, the experimental yield of vanillin was 4.63% ± 0.11% (dwb), which was in good agreement with the value predicted by the model. Compared to the traditional curing process (1.98%) and viscozyme extract (2.36%), the optimized method for the vanillin production significantly increased the yield by 133.85% and 96%, respectively.

  17. Rapid detection of frozen-then-thawed minced beef using multispectral imaging and Fourier transform infrared spectroscopy.

    Science.gov (United States)

    Ropodi, Athina I; Panagou, Efstathios Z; Nychas, George-John E

    2018-01-01

    In recent years, fraud detection has become a major priority for food authorities, as fraudulent practices can have various economic and safety consequences. This work explores ways of identifying frozen-then-thawed minced beef labeled as fresh in a rapid, large-scale and cost-effective way. For this reason, freshly-ground beef was purchased from seven separate shops at different times, divided in fifteen portions and placed in Petri dishes. Multi-spectral images and FTIR spectra of the first five were immediately acquired while the remaining were frozen (-20°C) and stored for 7 and 32days (5 samples for each time interval). Samples were thawed and subsequently subjected to similar data acquisition. In total, 105 multispectral images and FTIR spectra were collected which were further analyzed using partial least-squares discriminant analysis and support vector machines. Two meat batches (30 samples) were reserved for independent validation and the remaining five batches were divided in training and test set (75 samples). Results showed 100% overall correct classification for test and external validation MSI data, while FTIR data yielded 93.3 and 96.7% overall correct classification for FTIR test set and external validation set respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Effects of Oxidized Glutathione, Bovine Serum Albumin, Cysteine and Lycopene on the Quality of Frozen-Thawed Ram Semen

    Directory of Open Access Journals (Sweden)

    O. Uysal

    2007-01-01

    Full Text Available Free radicals are known to be involved in lipid peroxidation as well as DNA and sperm membrane damages that may lead to decreased sperm motility or cell death. The balance between free radical production and their detoxification may be an important factor in sperm survival and function before, during and after cryopreservation. The aim of this study was to determine the effects of the addition of the antioxidants of oxidized glutathione (GSSG, bovine serum albumin (BSA, cysteine and lycopene to freezing media on the post-thawing sperm characteristics, including motility, morphology, acrosome integrity, viability and membrane integrity. A total number of 42 ejaculates were collected using the artifi cial vagina from 4 Akkaraman rams and 10 replicates of the ejaculates were diluted with a Tris-based extender containing additives and no additives as control. GSSG (5 mM, BSA (20 mg/ml, cysteine (10 mM and lycopene (800 μg showed more positive effects than other concentrations of the supplements and controls in protecting sperm characteristics after the freezing-thawing process (P < 0.001. Many aspects of sperm protection, e.g. sperm motility, viability and membrane stabilisation of the sperm cells during relative cryopreservation, are the key factors in determining the preservation of sperm function. The results of this study provide a new approach to the cryopreservation of sperm from rams and related breeds, and thereby contribute to the improvement of these breeds for the world sheep industry.

  19. PVA/CM-chitosan/honey hydrogels prepared by using the combined technique of irradiation followed by freeze-thawing

    International Nuclear Information System (INIS)

    Afshari, M.J.; Sheikh, N.; Afarideh, H.

    2015-01-01

    Hydrogels with three components, poly(vinyl alcohol) (PVA), carboxymethylate chitosan (CM-chitosan) and honey have been prepared by using radiation method and radiation followed by freeze-thawing cycles technique (combinational method). The solid concentration of the polymer solution is 15 wt% and the ratios of PVA/CM-chitosan/honey are 10/1.5/3.5, 10/2/3, 10/3/2, and 10/3.5/1.5. The applied irradiation doses are 25, 30 and 40 kGy. Various tests have been done to evaluate the hydrogel properties to produce materials to be used as wound dressing. The results show that combinational method improves the mechanical strength of hydrogels while it has no significant effect on the water evaporation rate of gels. The combinational method decreases the swelling of hydrogels significantly, albeit this parameter is still acceptable for wound dressing. Microbiological analyses show that the hydrogel prepared by both methods can protect the wound from Escherichia coli bacterial infection. The wound healing test shows the good performance of the gels in mice. - Highlights: • Hydrogels prepared by the combination of irradiation and freeze-thawing methods. • Hydrogels with improved mechanical strength prepared by the combinational method. • The prepared hydrogels had acceptable transparency and degree of swelling. • The water evaporation rates of these hydrogels were pretty low. • Presences of honey in the formulation of gels led to a higher tissue regeneration

  20. Effect of cholesterol loaded cyclodextrin supplementation on tyrosine phosphorylation and apoptosis like changes in frozen thawed Hariana bull spermatozoa.

    Science.gov (United States)

    Yadav, Hanuman P; Kumar, Anuj; Shah, Nadeem; Chauhan, Dharmendra S; Saxena, Atul; Yadav, Sarvajeet; Swain, Dilip Kumar

    2017-07-01

    The beneficial effects of cholesterol loaded cyclodextrin (CLC) addition were evaluated in cryopreserved bull semen. Forty ejaculates were collected from Hariana bulls (n = 4), pooled and divided into 4 aliquots. All the aliquots were initially diluted in to egg yolk tris citrate and supplemented with CLC @ 0.5 mg (Group-II), 1.0 mg (G-III) and 2.0 mg (G-IV) CLC/120 × 10 6 spermatozoa or without CLC (G-I) that served as control. Extended semen was cryopreserved at -196 °C for 24 h. Seminal attributes like motility, viability, cryocapacitation like changes, tyrosine phosphorylation, apoptosis like changes in terms of mitochondrial transmembrane potential and DNA integrity were evaluated after equilibration and thawing. Results showed a significant increase in the motility, viability and acrosome intact spermatozoa in Group II as compared to other three groups. Further, the proportion of spermatozoa showing capacitation and acrosome reaction was also decreased (P spermatozoa. Addition of CLC significantly increased (P spermatozoa showing high transmembrane mitochondrial potential, and also, CLC @ 0.5 mg/120 × 10 6 in semen extender significantly decreased (P spermatozoa showing fragmented DNA after thawing as compared to control. Results of the present study indicate beneficial effects of CLC supplementation on cryodamage of spermatozoa by reducing the cryocapacitation and apoptosis like changes. Copyright © 2017 Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

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

    2017-05-19

    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 MS n ). The MALDI multi-stage mass spectrometry (MS) analysis of lipid A extracted from the Pseudomonas sp. strain PAMC 28618 demonstrated that the hexaacyl lipid A ([M-H] - at m/z 1616.5) contains a glucosamine (GlcN) disaccharide backbone, two phosphates, four main acyl chains and two branched acyl chains. Moreover, the lipid A molecule-based structural activity relationship with other terrestrial Gram-negative bacteria indicated that strain PAMC 28618 has an identical lipid A structure with the mesophilic Pseudomonas cichorii which can cause rot disease in endive (Cichorium endivia) and that their bacterial toxicities were equivalent. Therefore, the overall lipid A validation process provides a general strategy for characterizing bacteria that have been isolated from arctic permafrost and analyzing their respective pathogenicities.

  2. Effects of Seawater Corrosion and Freeze-Thaw Cycles on Mechanical Properties of Fatigue Damaged Reinforced Concrete Beams

    Directory of Open Access Journals (Sweden)

    Zijian Liu

    2015-01-01

    Full Text Available The effects of seawater corrosion and freeze-thaw cycles on the structural behavior of fatigue damaged reinforced concrete (FDRC beams were experimentally studied. Results show that the residual strength of FDRC beams reduces as the fatigue load level (the ratio of maximum fatigue load to the ultimate static load increases. The reduction in the loading capacity of FDRC beams in atmosphere environment was about 6.5% and 17.8% for given fatigue load levels of 0.2 and 0.3, respectively. However, if FDRC beams are exposed to the environment of seawater wet-dry cycles or to the environment of alternating actions of freeze-thaw and seawater immersion, as expected during the service life of RC bridge structures in coastal regions or in cold coastal regions, a more rapid reduction in the strength and stiffness of the beams is observed. The significance of an accurate simulation of working load and service condition RC bridge structures in coastal regions and cold coastal regions is highlighted.

  3. Effect of Multiple Freezing/Thawing Cycles on the Structural and Functional Properties of Waxy Rice Starch

    Science.gov (United States)

    Tao, Han; Yan, Juan; Zhao, Jianwei; Tian, Yaoqi; Jin, Zhengyu; Xu, Xueming

    2015-01-01

    The structural and functional properties of non-gelatinized waxy rice starch were investigated after 1, 3, 7, and 10 freezing/thawing cycles. Freezing caused an increasing damaged starch from 1.36% in native waxy rice starch to 5.77% in 10 freezing/thawing-treated starch (FTS), as evidenced by the cracking surface on starch granules. More dry matter concentration was leached, which was characterized by high amylopectin concentration (4.34 mg/mL). The leaching was accompanied by a decrease in relative crystallinity from 35.19% in native starch to 31.34% in 10 FTS. Freezing treatment also led to significant deviations in the functional characteristics, for instance decreased gelatinization temperature range, enthalpy, and pasting viscosities. The resistant starch content of 10FTS significantly decreased from 58.9% to 19%, whereas the slowly digested starch content greatly increased from 23.8% in native starch to 50.3%. The increase in susceptibility to enzyme hydrolysis may be attributed to porous granular surface, amylopectin leaching, and the decrease in the relative crystallinity caused by freezing water. PMID:26018506

  4. Effect of multiple freezing/thawing cycles on the structural and functional properties of waxy rice starch.

    Directory of Open Access Journals (Sweden)

    Han Tao

    Full Text Available The structural and functional properties of non-gelatinized waxy rice starch were investigated after 1, 3, 7, and 10 freezing/thawing cycles. Freezing caused an increasing damaged starch from 1.36% in native waxy rice starch to 5.77% in 10 freezing/thawing-treated starch (FTS, as evidenced by the cracking surface on starch granules. More dry matter concentration was leached, which was characterized by high amylopectin concentration (4.34 mg/mL. The leaching was accompanied by a decrease in relative crystallinity from 35.19% in native starch to 31.34% in 10 FTS. Freezing treatment also led to significant deviations in the functional characteristics, for instance decreased gelatinization temperature range, enthalpy, and pasting viscosities. The resistant starch content of 10FTS significantly decreased from 58.9% to 19%, whereas the slowly digested starch content greatly increased from 23.8% in native starch to 50.3%. The increase in susceptibility to enzyme hydrolysis may be attributed to porous granular surface, amylopectin leaching, and the decrease in the relative crystallinity caused by freezing water.

  5. Frozen-thawed day 5 blastocyst transfer is associated with a lower risk of ectopic pregnancy than day 3 transfer and fresh transfer.

    Science.gov (United States)

    Fang, Cong; Huang, Rui; Wei, Li-Na; Jia, Lei

    2015-03-01

    To determine the ectopic pregnancy rate with fresh versus frozen-thawed embryo transfers, and factors associated with ectopic pregnancy in patients undergoing IVF-ET. Retrospective analysis. Institutional IVF center. A total of 3,183 patients who received 3,340 blastocysts transfers: 1,994 fresh transfers and 1,346 frozen-thawed transfers. Patients received fresh day 3 embryos (F-D3 group), fresh day 5 blastocysts (F-D5 group), frozen-thawed day 3 embryos (T-D3 group), or frozen-thawed day 5 or 6 blastocysts (T-D5 and T-D6 groups). Ectopic pregnancy rate. The ectopic pregnant rates were 2.4% in the F-D3 group, 1.7% in F-D5, 1.9% in T-D3, 0.3% in T-D5, and 0.5% in T-D6. The ectopic pregnant rate of the T-D3 group was significantly greater than that of the T-D5 and T-D6 groups (1.9% vs. 0.3% and 0.5%). The ectopic pregnancy rate of the F-D5 group was significantly greater than that of the T-D5 group (1.7% vs. 0.3%). Frozen-thawed day 5 blastocyst transfer is associated with a lower ectopic pregnancy rate than frozen-thawed day 3 transfer and fresh transfer in patients undergoing IVF-ET. Copyright © 2015 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

  6. Frozen-thawed rhesus sperm retain normal morphology and highly progressive motility but exhibit sharply reduced efficiency in penetrating cervical mucus and hyualuronic acid gel

    Science.gov (United States)

    Tollner, Theodore L.; Dong, Qiaoxiang; VandeVoort, Catherine A.

    2011-01-01

    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 sperm to penetrate periovulatory cervical mucus (CM). Motile sperm concentration of pre–freeze (“fresh”) and post-thawed (“thawed”) samples from 5 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

  7. The Impact of Different Preservation Conditions and Freezing-Thawing Cycles on Quality of RNA, DNA, and Proteins in Cancer Tissue.

    Science.gov (United States)

    Wang, Yaogeng; Zheng, Hong; Chen, Jie; Zhong, Xiaorong; Wang, Yu; Wang, Zhu; Wang, Yanping

    2015-10-01

    High-quality cancer tissues are essential for future research, especially molecular research. For the sake of better quality of tissues, some storage methods are chosen according to lab conditions. But the impact of different storing conditions on the quality of RNA, DNA (especially the degree of DNA methylation), and protein of tissues that have undergone a thawing process, is not clear. We analyzed the influence of different storage conditions including in RNALater solution, normal saline, Opti-mum Cutting Temperature compound (OCT), and snap frozen with no protective reagent (as control) in paired tissue samples on the quality of RNA (RNA Integrity Number value and mRNA expression), DNA quality (DNA amplification and DNA methylation degree of gene RASSF1a), and protein quality. Further, we analyzed the RNA quality of tissues that underwent three freeze-thaw cycles. The RNALater-treated group retained good RNA quality as expected on three repeated freeze-thaw cycles (RIN>8), but the snap-frozen tissues showed relatively poor results after one freeze-thaw cycle (RINRNA from saline- and OCT-treated groups also yielded good results when we repeated freezing and thawing one time (RIN>7) and two times (RIN>6). The impact of different storing conditions on DNA amplification is small. However, DNA methylation and protein quality are different with different storing conditions. OCT seems to be more secure and stable compared with other two experimental groups, and show a similar trend with control group. In consideration of budget and efficiency, we suggest OCT as the best storing method that not only preserves RNA quality during the freezing-thawing process well, but also ensures more secure and stable DNA and protein.

  8. Effect of post-thaw addition of seminal plasma on motility, viability and chromatin integrity of cryopreserved donkey jack (Equus asinus) spermatozoa.

    Science.gov (United States)

    Sabatini, C; Mari, G; Mislei, B; Love, Cc; Panzani, D; Camillo, F; Rota, A

    2014-12-01

    Pregnancy rates in donkeys after artificial insemination with cryopreserved semen are still low, compared to the horse species. Addition of autologous seminal plasma to frozen-thawed semen appeared to improve pregnancy rates. The aims of this study were to evaluate (1) sperm motility and plasma membrane integrity after thawing (T0) and after one and 2 h (T1 and T2) of post-thaw incubation in either 0% (SP0) or 70% (SP70) autologous seminal plasma and (2) sperm motility, plasma membrane integrity and DNA quality (%COMP-αt) after thawing (T0) and after 2 and 4 h (T2 and T4) of post-thaw incubation in either 0% (SP0), 5% (SP5) or 20% (SP20) homologous seminal plasma. In experiment 1, seminal plasma decreased total and progressive sperm motility and plasma membrane intact spermatozoa immediately after dilution and at all following time points (p < 0.05). In experiment 2, total and progressive motility did not differ between treatments immediately after dilution and between SP0 and SP5 at T2, while they were lower in both SP5 and SP20 than in SP0 at T4. Plasma membrane intact sperm cells did not differ between SP0 and SP5 and were lower in SP20 at all time points. DNA quality was not affected by treatment immediately after dilution and was significantly worse for SP20 after 4 h of incubation (p < 0.05). The post-thaw addition of seminal plasma at the tested concentrations did not improve donkey frozen semen characteristics in vitro over time. © 2014 Blackwell Verlag GmbH.

  9. Enhanced metabolic function of human hepatocytes cryopreserved with low concentration me2so and polyol additives at -80C.

    Science.gov (United States)

    Yang, B; Liu, B L; Zhou, X L; Shen, L; Huang, D H

    2013-01-01

    The metabolic function of cryopreserved cells, in addition to cell viability after thawing, is an important parameter in any successful cryopreservation protocol. Dimethyl sulfoxide (Me2SO) is known to affect the differentiation of recovered cells. In this study, we report that sugars and sugar alcohols increases cell recovery, and also improves the metabolic function of human hepatocytes that are cryopreserved using low concentration Me2SO (5%). Three sugars (glucose, sucrose, and trehalose) and three sugar alcohols (xylitol, maltol, and sorbitol) have been tested. Cell viability after thaw and 24-h post-thaw attachment rate of cryopreserved human hepatocytes were assessed. Post-thaw metabolic activities (albumin, glucose, urea content) were measured, and cell proliferation was observed with inverted microscope. Cell viability, post-thaw attachment rate and metabolic activity of cryopreserved hepatocytes are enhanced by the addition of 0.4M sorbitol into 5% Me2SO solution. The study concludes that 5% Me2SO + 0.4M sorbitol can replace the 10% Me2SO method for cryopreservation of human hepatocytes at -80C freezer. The new solution may reduce the side effects on the patients and improve the safety of using cryopreserved hepatocytes.

  10. Microbial spoilage and formation of biogenic amines in fresh and thawed modified atmosphere-packed salmon ( Salmo salar ) at 2 degrees C

    DEFF Research Database (Denmark)

    Emborg, Jette; Laursen, B.G.; Rathjen, T.

    2002-01-01

    Aims: To evaluate the microbial spoilage, formation of biogenic amines and shelf life of chilled fresh and frozen/thawed salmon packed in a modified atmosphere and stored at 2 degrees C.Methods and Results: The dominating microflora, formation of biogenic amines and shelf life were studied in two...... series of storage trials with naturally contaminated fresh and thawed modified atmosphere-packed (MAP) salmon at 2 degrees C. Photobacterium phosphoreum dominated the spoilage microflora of fresh MAP salmon at more than 106 cfu g-1 and the activity of this specific spoilage organism (SSO) limited...

  11. Influences of Land Use/Cover Types on Nitrous Oxide Emissions during Freeze-Thaw Periods from Waterlogged Soils in Inner Mongolia.

    Directory of Open Access Journals (Sweden)

    Zedong Lu

    Full Text Available Nitrous oxide emissions during freeze/thaw periods contribute significantly to annual soil N2O emissions budgets in middle- and high-latitude areas; however, the freeze/thaw-related N2O emissions from waterlogged soils have hardly been studied in the Hulunber Grassland, Inner Mongolia. For this study, the effects of changes in land use/cover types on N2O emissions during freeze-thaw cycles were investigated to more accurately quantify the annual N2O emissions from grasslands. Soil cores from six sites were incubated at varying temperature (ranging from -15 to 10°C to simulate freeze-thaw cycles. N2O production rates were low in all soil cores during freezing periods, but increased markedly after soil thawed. Mean rates of N2O production differed by vegetation type, and followed the sequence: Leymus chinensis (LC and Artemisia tanacetifolia (AT steppes > LC steppes ≥ Stipa baicalensis (SB steppes. Land use types (mowing and grazing had differing effects on freeze/thaw-related N2O production. Grazing significantly reduced N2O production by 36.8%, while mowing enhanced production. The production of N2O was related to the rate at which grassland was mowed, in the order: triennially (M3 > once annually (M1 ≥ unmown (UM. Compared with the UM control plot, the M3 and M1 mowing regimes enhanced N2O production by 57.9% and 13.0% respectively. The results of in situ year-round measurements showed that large amounts of N2O were emitted during the freeze-thaw period, and that annual mean fluxes of N2O were 9.21 μg N2O-N m-2 h-1 (ungrazed steppe and 6.54 μg N2O-N m-2 h-1 (grazed steppe. Our results further the understanding of freeze/thaw events as enhancing N2O production, and confirm that different land use/cover types should be differentiated rather than presumed to be equivalent, regarding nitrous oxide emission. Even so, further research involving multi-year and intensive measurements of N2O emission is still needed.

  12. Effects of single dose GnRH agonist as luteal support on pregnancy outcome in frozen-thawed embryo transfer cycles: an RCT

    Directory of Open Access Journals (Sweden)

    Robab Davar

    2015-08-01

    Full Text Available Background: There is no doubt that luteal phase support is essential to enhance the reproductive outcome in IVF cycles. In addition to progesterone and human chorionic gonadotropin, several studies have described GnRH agonists as luteal phase support to improve implantation rate, pregnancy rate and live birth rate, whereas other studies showed dissimilar conclusions. All of these studies have been done in fresh IVF cycles. Objective: To determine whether an additional GnRH agonist administered at the time of implantation for luteal phase support in frozen-thawed embryo transfer (FET improves the embryo developmental potential. Materials and Methods: This is a prospective controlled trial study in 200 FET cycles, patients were randomized on the day of embryo transfer into group 1 (n=100 to whom a single dose of GnRH agonist (0.1 mg triptorelin was administered three days after transfer and group 2 (n=100, who did not receive agonist. Both groups received daily vaginal progesterone suppositories plus estradiol valerate 6 mg daily. Primary outcome measure was clinical pregnancy rate. Secondary outcome measures were implantation rate, chemical, ongoing pregnancy rate and abortion rate. Results: A total of 200 FET cycles were analyzed. Demographic data and embryo quality were comparable between two groups. No statistically significant difference in clinical and ongoing pregnancy rates was observed between the two groups (26% versus 21%, p=0.40 and 21% versus 17%, p=0.37, respectively. Conclusion: Administration of a subcutaneous GnRH agonist at the time of implantation does not increase clinical or ongoing pregnancy.

  13. PVA matches human liver in needle-tissue interaction.

    Science.gov (United States)

    de Jong, Tonke L; Pluymen, Loes H; van Gerwen, Dennis J; Kleinrensink, Gert-Jan; Dankelman, Jenny; van den Dobbelsteen, John J

    2017-05-01

    Medical phantoms can be used to study needle-tissue interaction and to train medical residents. The purpose of this research is to study the suitability of polyvinyl alcohol (PVA) as a liver tissue mimicking material in terms of needle-tissue interaction. Insertions into ex-vivo human livers were used for reference. Six PVA samples were created by varying the mass percentage of PVA to water (4m% and 7m%) and the number of freeze-thaw cycles (1, 2 and 3 cycles, 16hours of freezing at -19°C, 8hours of thawing). The inner needle of an 18 Gauge trocar needle with triangular tip was inserted 13 times into each of the samples, using an insertion velocity of 5 mm/s. In addition, 39 insertions were performed in two ex-vivo human livers. Axial forces on the needle were captured during insertion and retraction and characterized by friction along the needle shaft, peak forces, and number of peak forces per unit length. The concentration of PVA and the number of freeze-thaw cycles both influenced the mechanical interaction between needle and specimen. Insertions into 4m% PVA phantoms with 2 freeze-thaw cycles were comparable to human liver in terms of estimated friction along the needle shaft and the number of peak forces. Therefore, these phantoms are considered to be suitable liver mimicking materials for image-guided needle interventions. The mechanical properties of PVA hydrogels can be influenced in a controlled manner by varying the concentration of PVA and the number of freeze-thaw cycles, to mimic liver tissue characteristics. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. The freeze-thaw stress response of the yeast Saccharomyces cerevisiae is growth phase specific and is controlled by nutritional state via the RAS-cyclic AMP signal transduction pathway.

    Science.gov (United States)

    Park, J I; Grant, C M; Attfield, P V; Dawes, I W

    1997-10-01

    The ability of cells to survive freezing and thawing is expected to depend on the physiological conditions experienced prior to freezing. We examined factors affecting yeast cell survival during freeze-thaw stress, including those associated with growth phase, requirement for mitochondrial functions, and prior stress treatment(s), and the role played by relevant signal transduction pathways. The yeast Saccharomyces cerevisiae was frozen at -20 degrees C for 2 h (cooling rate, less than 4 degrees C min-1) and thawed on ice for 40 min. Supercooling occurred without reducing cell survival and was followed by freezing. Loss of viability was proportional to the freezing duration, indicating that freezing is the main determinant of freeze-thaw damage. Regardless of the carbon source used, the wild-type strain and an isogenic petite mutant ([rho 0]) showed the same pattern of freeze-thaw tolerance throughout growth, i.e., high resistance during lag phase and low resistance during log phase, indicating that the response to freeze-thaw stress is growth phase specific and not controlled by glucose repression. In addition, respiratory ability and functional mitochondria are necessary to confer full resistance to freeze-thaw stress. Both nitrogen and carbon source starvation led to freeze-thaw tolerance. The use of strains affected in the RAS-cyclic AMP (RAS-cAMP) pathway or supplementation of an rca1 mutant (defective in the cAMP phosphodiesterase gene) with cAMP showed that the freeze-thaw response of yeast is under the control of the RAS-cAMP pathway. Yeast did not adapt to freeze-thaw stress following repeated freeze-thaw treatment with or without a recovery period between freeze-thaw cycles, nor could it adapt following pretreatment by cold shock. However, freeze-thaw tolerance of yeast cells was induced during fermentative and respiratory growth by pretreatment with H2O2, cycloheximide, mild heat shock, or NaCl, indicating that cross protection between freeze-thaw stress

  15. Detection of lipid peroxidation in frozen-thawed avian spermatozoa using C(11)-BODIPY(581/591).

    Science.gov (United States)

    Partyka, Agnieszka; Lukaszewicz, Ewa; Niżański, Wojciech; Twardoń, Jan

    2011-06-01

    The aim of this study was to perform flow cytometric analysis of C11-BODIPY581/591 oxidation in fowl and geese sperm as a marker for membrane lipid peroxidation (LPO) and to establish if the cryopreservation process would make sperm membranes more susceptible to oxidative stress. The experiment was carried out on 10 meat type line Flex roosters and 10 White Koluda® geese. The semen was collected two times a week, by dorso-abdominal massage method and pooled from 10 individuals of each species. Fowl semen samples were subjected to cryopreservation using the "pellet" method and Dimethylacetamide (DMA) as a cryoprotectant. Geese semen samples were cryopreserved in plastic straws in a programmable freezing unit with Dimethyloformamide (DMF) as the cryoprotectant. A fluorescent lipid probe C11-BODIPY581/591 provided with two double bonds that are oxidized during their contact with ROS, was used for the purpose of the assessment of the LPO in freshly diluted semen samples and frozen-thawed semen samples. This probe changes its color according to its state (non peroxidized: red; peroxidized: green). Flow cytometric analysis was used to monitor these changes. The White Koluda® geese fresh semen had a higher level of LPO than the Flex fresh semen (P > 0.01). The cryopreservation of fowl semen significantly (P > 0.01) increased the percentage of live and dead spermatozoa with lipid peroxidation. In frozen-thawed semen of White Koluda® geese the percentage of live spermatozoa with LPO significantly decreased (P > 0.05) whereas significantly (P > 0.01) higher level of dead cells with LPO was observed. There were significant differences between the two studied species. After thawing, the percentage of live and dead spermatozoa with lipid peroxidation was higher in fowl semen than in geese semen (P > 0.01). In conclusion, our data clearly indicate the existence of species specific differences in susceptibility of spermatozoa to the oxidation of PUFAs in the cell membranes

  16. Effects of antioxidants on post-thawed bovine sperm and oxidative stress parameters: antioxidants protect DNA integrity against cryodamage.

    Science.gov (United States)

    Bucak, Mustafa Numan; Tuncer, Pürhan Barbaros; Sarıözkan, Serpil; Başpınar, Nuri; Taşpınar, Mehmet; Coyan, Kenan; Bilgili, Ali; Akalın, Pınar Peker; Büyükleblebici, Serhat; Aydos, Sena; Ilgaz, Seda; Sunguroğlu, Asuman; Oztuna, Derya

    2010-12-01

    This study was conducted to determine the effects of methionine, inositol and carnitine on sperm (motility, abnormality, DNA integrity and in vivo fertility) and oxidative stress parameters (lipid peroxidation, total glutathione and antioxidant potential levels) of bovine semen after the freeze-thawing process. Nine ejaculates, collected with the aid of an artificial vagina twice a week from each Simmental bovine, were included in the study. Each ejaculate, splitted into seven equal groups and diluted in Tris-based extender containing methionine (2.5 and 7.5 mM), carnitine (2.5 and 7.5 mM), inositol (2.5 and 7.5 mM) and no additive (control), was cooled to 5 °C and then frozen in 0.25 ml straws. Frozen straws were then thawed individually at 37 °C for 20s in a water bath for the evaluation. The extender supplemented with 7.5 mM doses of carnitine and inositol led to higher subjective motility percentages (61.9±1.3% and 51.3±1.6%) compared to the other groups. The addition of methionine and carnitine at doses of 2.5 and 7.5 mM and inositol at doses of 7.5mM provided a greater protective effect in the percentages of total abnormality in comparison to the control and inositol 2.5 mM (P control, thus reducing the DNA damage (P control group (P > 0.05). The maintenance of AOP level in methionine 2.5 mM was demonstrated to be higher (5.06±0.38 mM) than that of control (0.96±0.29 mM) following the freeze-thawing (P process protected the DNA integrity against the cryodamage. Furthermore, future research should focus on the molecular mechanisms of the antioxidative effects of the antioxidants methionine, carnitine and inositol during cryopreservation. Copyright © 2010 Elsevier Inc. All rights reserved.

  17. Ferrrate(VI) and freeze-thaw treatment for oxidation of hormones and inactivation of fecal coliforms in sludge.

    Science.gov (United States)

    Diak, James; Örmeci, Banu

    2017-04-01

    This study examined the individual and combined effects of potassium ferrate(VI) additions and freeze-thaw conditioning for the treatment and dewatering of wastewater sludge in cold climates, with particular focus on the inactivation of fecal coliforms and oxidation of estrogens, androgens, and progestogens. The first phase of the study evaluated the effects of potassium ferrate(VI) pre-treatment followed by freeze-thaw at -20 °C using a low (0.5 g/L) and high (5.0 g/L) dose of potassium ferrate(VI). The results showed that pre-treatment of anaerobically digested sludge with 5 g/L of potassium ferrate(VI) reduced the concentration of fecal coliforms in the sludge cake to below 100 MPN/g DS. The second phase evaluated the ability of ferrate(VI) to oxidise selected hormones in sludge. Anaerobically digested sludge samples were spiked with 10 different hormones: estrone (E1), 17α-estradiol, 17β-estradiol (E2), estriol (E3), 17α-ethinylestradiol (EE2), equilin, mestranol, testosterone, norethindrone and norgestrel in two groups of low (3-75 ng/mL) and high (12-300 ng/L) concentration ranges of hormones. The samples were treated with either 0.5 or 1.0 g/L of potassium ferrate(VI), and hormone concentrations were measured again after treatment. Potassium ferrate(VI) additions as low as 1.0 g/L reduced the concentration of estrogens in sludge. Potassium ferrate(VI) additions of 0.5 and 1.0 g/L were less effective at reducing the concentrations of androgens and progestogens. Increasing ferrate(VI) dose would likely result in more substantial decreases in the concentrations of fecal coliforms and hormones. The results of this study indicate that the combined use of freeze-thaw and ferrate(VI) has the potential to provide a complete sludge treatment solution in cold regions.

  18. Optimization of a novel nylon mesh container for human embryo ultrarapid vitrification.

    Science.gov (United States)

    Nakashima, Akira; Ino, Nao; Kusumi, Maki; Ohgi, Shirei; Ito, Megumu; Horikawa, Takashi; Nakagawa, Koji; Saito, Takakazu; Kamura, Toshiharu; Saito, Hidekazu

    2010-05-01

    To evaluate the efficacy of a nylon mesh container in vitrification of human embryos and to determine the optimal osmotic pressure of the initial thawing solution. Retrospective analysis. National Center for Child Health and Development, Tokyo, Japan. Infertile patients undergoing either in vitro fertilization or intracytoplasmic sperm injection in our hospital. Embryos, at the cleavage stage, were cryopreserved using the vitrification method in either a plastic straw or a nylon mesh container. The embryos were thawed using an initial osmotic pressure of either 0.5 M or 1.0 M sucrose with subsequent step-wise dilution. After thawing, the embryos were transferred to the uterus. Survival rate of blastomeres, embryo survival rate, implantation, and pregnancy rates, cancellation rate because of embryo damage. Use of nylon mesh and the 1.0 M sucrose thawing solution significantly improved blastomere survival rate (98.0 +/- 1.0%, mean +/- SEM), pregnancy rate (41.0%) and implantation rate (32.3%). Vitrification using a nylon mesh container and subsequent thawing in a 1.0 M sucrose solution is an easy and inexpensive method that improves the reliability of embryo cryopreservation of embryos without adverse effects on clinical outcomes. Copyright 2010 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

  19. Temporal Monitoring of the Soil Freeze-Thaw Cycles over a Snow-Covered Surface by Using Air-Launched Ground-Penetrating Radar

    Directory of Open Access Journals (Sweden)

    Khan Zaib Jadoon

    2015-09-01

    Full Text Available We tested an off-ground ground-penetrating radar (GPR system at a fixed location over a bare agricultural field to monitor the soil freeze-thaw cycles over a snow-covered surface. The GPR system consisted of a monostatic horn antenna combined with a vector network analyzer, providing an ultra-wideband stepped-frequency continuous-wave radar. An antenna calibration experiment was performed to filter antenna and back scattered effects from the raw GPR data. Near the GPR setup, sensors were installed in the soil to monitor the dynamics of soil temperature and dielectric permittivity at different depths. The soil permittivity was retrieved via inversion of time domain GPR data focused on the surface reflection. Significant effects of soil dynamics were observed in the time-lapse GPR, temperature and dielectric permittivity measurements. In particular, five freeze and thaw events were clearly detectable, indicating that the GPR signals respond to the contrast between the dielectric permittivity of frozen and thawed soil. The GPR-derived permittivity was in good agreement with sensor observations. Overall, the off-ground nature of the GPR system permits non-invasive time-lapse observation of the soil freeze-thaw dynamics without disturbing the structure of the snow cover. The proposed method shows promise for the real-time mapping and monitoring of the shallow frozen layer at the field scale.

  20. Effect of non-sperm cells removal with single-layer colloidal centrifugation on myeloperoxidase concentration in post-thaw equine semen.

    Science.gov (United States)

    Ponthier, Jérôme; Teague, Sheila R; Franck, Thierry Y; de la Rebière, Geoffroy; Serteyn, Didier D; Brinsko, Steven P; Love, Charles C; Blanchard, Terry L; Varner, Dickson D; Deleuze, Stéfan C

    2013-12-01

    Myeloperoxidase (MPO) is a pro-oxidant enzyme contained in and released by neutrophils during degranulation or after lysis. Post-thaw semen contains MPO and its concentration is associated with decreased sperm motility. Recently, MPO concentration in post-thaw semen was shown to be associated with the presence of non-sperm cells (NSC). The objective of this study was to evaluate the effect of a single-layer colloidal centrifugation before cryopreservation on NSC and MPO concentrations in equine semen. The experimental design consisted of freezing semen with or without previous centrifugation through two concentrations of single-layer colloid media. Non-sperm cells and MPO concentrations were assessed in pellet and upper layer at each step of the procedure and MPO was detected in cells by immunocytochemistry. Single-layer colloid centrifugation decreased NSC and MPO concentrations in post-thaw semen. The MPO concentration was correlated with concentration of NSC in the upper layer of the supernatant. In post-thaw semen, with or without previous single-layer colloid centrifugation, MPO concentration was correlated with concentration of NSC. Overall, neutrophils were rarely observed and NSC were mainly epithelial cells or cellular debris, as demonstrated by MPO immunocytochemistry. At all steps of the semen processing and cryopreservation, MPO immunostaining was clearly identified only on NSC. In conclusion, our study shows that NSC present in fresh semen release MPO during freezing. Copyright © 2013 Elsevier Inc. All rights reserved.

  1. Chilled and post-thawed semen characteristics of buffalo semen diluted in tris extender enriched with date palm pollen grains (TPG

    Directory of Open Access Journals (Sweden)

    Reda I. El-Sheshtawy

    2016-05-01

    Conclusions: The aqueous cold infusion or extract of the DPPG, added to the TCF extender with or without the addition of egg yolk, proved its good preserving and maintaining capacity of chilled and thawed buffalo bull sperms which was expressed mainly by the sperm motility.

  2. The effects of different levels of catalase and superoxide dismutase in modified Beltsville extender on rooster post-thawed sperm quality.

    Science.gov (United States)

    Amini, Mahmood Reza; Kohram, Hamid; Zare-Shahaneh, Ahmad; Zhandi, Mahdi; Sharideh, Hossein; Nabi, Mohammad Mehdi

    2015-06-01

    Oxidative damage of sperm by means of reactive oxygen species generated by the cellular components of semen is one of the main reasons for decreased sperm motility and fertility during the freeze-thawing process. This study was conducted to determine the influence of catalase (CAT) and superoxide dismutase (SOD) on rooster sperm motility, viability and MDA level after freezing and thawing. Semen samples from 10 sexually-mature Ross 308 breeder roosters were collected and pooled, divided into nine equal parts and diluted with modified Beltsville extender containing no antioxidants (control), or supplemented with 50, 100, 200 and 300 μg/mL CAT, or 50, 100, 200 and 300 U/mL SOD. After thawing, sperm motility and motion parameters were assessed using a CASA system. Sperm viability and MDA level were assessed by eosin-nigrosin and MDA test, respectively. The results of this experiment showed that the extender supplemented with 100 and 200 μg CAT, and 50 U SOD had the highest sperm motility (Peffect on quality of post-thawed rooster semen. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Effects of supplementation of iodixanol to semen extender on quality and fertilization ability of frozen-thawed Thai native bull sperm.

    Science.gov (United States)

    Chuawongboon, Phirawit; Sirisathien, Saksiri; Pongpeng, Jatuporn; Sakhong, Denpong; Nagai, Takashi; Vongpralub, Thevin

    2017-09-01

    This study investigates the effects of iodixanol supplementation in varied concentrations to Tris egg yolk (TEY) extender on the quality and fertilization ability of frozen-thawed sperm of Thai native bulls. Each ejaculate was divided into four different groups, as follows: sperm were treated with TEY extender (control group) and TEY extender supplemented with three different concentrations of iodixanol (1.25%, 2.50% and 5.00%). Semen straws were frozen in liquid nitrogen vapor. After thawing, sperm motility characteristics, viability, plasma membrane integrity and acrosome integrity were determined. Also, frozen-thawed spermatozoa from all groups were used for in vitro fertilization and artificial insemination (AI) in natural estrus Thai native cows. The results showed that the post-thaw quality of the 2.50% iodixanol group was superior to the other iodixanol groups (P fertilization ability and pregnancy rate after AI (P > 0.05). It can be concluded that the supplementation of 2.50% iodixanol extender significantly improves the progressive motility, viability, plasma membrane integrity and acrosome integrity of cryopreserved semen from Thai native bulls, but it has no beneficial effect on in vitro fertilization ability and pregnancy rate after AI. © 2017 Japanese Society of Animal Science.

  4. Nitrogen deposition may enhance soil carbon storage via change of soil respiration dynamic during a spring freeze-thaw cycle period.

    Science.gov (United States)

    Yan, Guoyong; Xing, Yajuan; Xu, Lijian; Wang, Jianyu; Meng, Wei; Wang, Qinggui; Yu, Jinghua; Zhang, Zhi; Wang, Zhidong; Jiang, Siling; Liu, Boqi; Han, Shijie

    2016-06-30

    As crucial terrestrial ecosystems, temperate forests play an important role in global soil carbon dioxide flux, and this process can be sensitive to atmospheric nitrogen deposition. It is often reported that the nitrogen addition induces a change in soil carbon dioxide emission in growing season. However, the important effects of interactions between nitrogen deposition and the freeze-thaw-cycle have never been investigated. Here we show nitrogen deposition delays spikes of soil respiration and weaken soil respiration. We found the nitrogen addition, time and nitrogen addition×time exerted the negative impact on the soil respiration of spring freeze-thaw periods due to delay of spikes and inhibition of soil respiration (p nitrogen), 39% (medium-nitrogen) and 36% (high-nitrogen) compared with the control. And the decrease values of soil respiration under medium- and high-nitrogen treatments during spring freeze-thaw-cycle period in temperate forest would be approximately equivalent to 1% of global annual C emissions. Therefore, we show interactions between nitrogen deposition and freeze-thaw-cycle in temperate forest ecosystems are important to predict global carbon emissions and sequestrations. We anticipate our finding to be a starting point for more sophisticated prediction of soil respirations in temperate forests ecosystems.

  5. Freeze-thaw method improves the detection of volatile compounds in insects using Headspace Solid-Phase Microextraction (HS-SPME)

    Science.gov (United States)

    Headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography–mass spectrometry (GC-MS) is commonly used in analyzing insect volatiles. In order to improve the detection of volatiles in insects, a freeze-thaw method was applied to insect samples before the HS-SPME-GC-MS analysis. ...

  6. Temporal Monitoring of the Soil Freeze-Thaw Cycles over a Snow-Covered Surface by Using Air-Launched Ground-Penetrating Radar

    KAUST Repository

    Jadoon, Khan

    2015-09-18

    We tested an off-ground ground-penetrating radar (GPR) system at a fixed location over a bare agricultural field to monitor the soil freeze-thaw cycles over a snow-covered surface. The GPR system consisted of a monostatic horn antenna combined with a vector network analyzer, providing an ultra-wideband stepped-frequency continuous-wave radar. An antenna calibration experiment was performed to filter antenna and back scattered effects from the raw GPR data. Near the GPR setup, sensors were installed in the soil to monitor the dynamics of soil temperature and dielectric permittivity at different depths. The soil permittivity was retrieved via inversion of time domain GPR data focused on the surface reflection. Significant effects of soil dynamics were observed in the time-lapse GPR, temperature and dielectric permittivity measurements. In particular, five freeze and thaw events were clearly detectable, indicating that the GPR signals respond to the contrast between the dielectric permittivity of frozen and thawed soil. The GPR-derived permittivity was in good agreement with sensor observations. Overall, the off-ground nature of the GPR system permits non-invasive time-lapse observation of the soil freeze-thaw dynamics without disturbing the structure of the snow cover. The proposed method shows promise for the real-time mapping and monitoring of the shallow frozen layer at the field scale.

  7. Experimental Investigation of the Variation of Concrete Pores under the Action of Freeze-Thaw Cycles by Using X-Ray CT

    Directory of Open Access Journals (Sweden)

    Jie Yuan

    2014-01-01

    Full Text Available The variation of concrete pores under the action of freeze-thaw cycles was investigated experimentally by using the X-ray CT. Firstly, the statistical characteristics of pores of concrete specimens were obtained by using the X-ray image analysis. Secondly, the variation of porosity and pore volume of concrete pores were analyzed and discussed by comparing with above characteristics. Thirdly, the failure process of the concrete specimens acted by the freeze-thaw cycles was investigated by scanning the interior of concrete specimens. The results showed that the pore volumes of concrete pores whose volumes were located at the interval [0.5 mm3, 20 mm3] have no big variation in both the amounts and volume of concrete pores, while others were found to have huge change during the process of experiment. The extent of damage acted by the repeated freezing and thawing gradually ranged from surface to complete disintegration of the interior of concrete specimens after 30 cycles of freeze-thaw acting.

  8. Liposome encapsulated soy lecithin and cholesterol can efficiently replace chicken egg yolk in human semen cryopreservation medium.

    Science.gov (United States)

    Mutalik, Srinivas; Salian, Sujith Raj; Avadhani, Kiran; Menon, Jyothsna; Joshi, Haritima; Hegde, Aswathi Raju; Kumar, Pratap; Kalthur, Guruprasad; Adiga, Satish Kumar

    2014-06-01

    Cryopreservation of spermatozoa plays a significant role in reproductive medicine and fertility preservation. Chicken egg yolk is used as an extender in cryopreservation of human spermatozoa using glycerol egg yolk citrate (GEYC) buffered medium. Even though 50% survival of spermatozoa is generally achieved with this method, the risk of high levels of endotoxins and transmission pathogens from chicken egg yolk is a matter of concern. In the present study we attempted to establish a chemically defined cryopreservation medium which can replace the chicken egg yolk without affecting sperm survival. Ejaculates from 28 men were cryopreserved with GEYC based freezing medium or liposome encapsulated soy lecithin-cholesterol based freezing medium (LFM). The semen samples were subjected to rapid thawing after 14 days of storage in liquid nitrogen. Post-thaw analysis indicated significantly higher post-thaw motility and sperm survival in spermatozoa cryopreserved with LFM compared to conventional GEYC freezing medium. The soy lecithin and cholesterol at the ratio of 80:20 with sucrose showed the highest percentage of post-thaw motility and survival compared to the other compositions. In conclusion, chemically defined cryopreservation medium with liposome encapsulated soy lecithin and cholesterol can effectively replace the chicken egg yolk from human semen cryopreservation medium without compromising post-thaw outcome.

  9. Laboratory and numerical experiments on water and energy fluxes during freezing and thawing in the unsaturated zone

    Science.gov (United States)

    Holländer, Hartmut; Montasir Islam, Md.; Šimunek, Jirka

    2017-04-01

    Frozen soil has a major effect in many hydrologic processes, and its effects are difficult to predict. A prime example is flood forecasting during spring snowmelt within the Canadian Prairies. One key driver for the extent of flooding is the antecedent soil moisture and the possibility for water to infiltrate into frozen soils. Therefore, these situations are crucial for accurate flood prediction during every spring. The main objective of this study was to evaluate the water flow and heat transport within HYDRUS-1D version 4.16 and with Hansson's model, which is a detailed freezing/thawing module (Hansson et al., 2004), to predict the impact of frozen and partly frozen soil on infiltration. We developed a standardized data set of water flow and heat transport into (partial) frozen soil by laboratory experiments using fine sand. Temperature, soil moisture, and percolated water were observed at different freezing conditions as well as at thawing conditions. Significant variation in soil moisture was found between the top and the bottom of the soil column at the starting of the thawing period. However, with increasing temperature, the lower depth of the soil column showed higher moisture as the soil became enriched with moisture due to the release of heat by soil particles during the thawing cycle. We applied vadose zone modeling using the results from the laboratory experiments. The simulated water content by HYDRUS-1D 4.16 showed large errors compared to the observed data showing by negative Nash-Sutcliffe Efficiency. Hansson's model was not able to predict soil water fluxes due to its unstable behavior (Šimunek et al., 2016). The soil temperature profile simulated using HYDRUS-1D 4.16 was not able to predict the release of latent heat during the phase change of water that was visible in Hansson's model. Hansson's model includes the energy gain/loss due to the phase change in the amount of latent energy stored in the modified heat transport equation. However, in

  10. Boar seminal plasma inhibits cryo-capacitation of frozen-thawed ram sperm and improves fertility following intracervical insemination.

    Science.gov (United States)

    Fang, Yi; Zhong, Rongzhen; Zhang, Xiaosheng; Zhang, Jinlong; Zhou, Daowei

    2018-01-01

    Cryopreservation has numerous deleterious effects on sperm structure and function, which can be reduced by adding seminal plasma (SP), either autologous or heterologous. The objective was to determine effects of adding boar SP to the freezing extender on sperm quality, tyrosine phosphorylation and fertilizing ability of frozen-thawed ram sperm. Semen was collected from eight Small-tail Han rams and extended in a glucose-egg yolk buffer supplemented with 0, 20, 40, or 60% porcine SP (from Large white boars). Compared to all other groups, 40% boar SP increased sperm viability and motility (P intracervical AI (47.5 vs 33.3%; P < 0.05), apparently due to inhibition of cryo-capacitation, although pregnancy rate for intravaginal AI was not affected (31.6 vs 30.0%). Copyright © 2017. Published by Elsevier Inc.

  11. Mix design for improved strength and freeze-thaw durability of pervious concrete fill in Pearl-Chain Bridges

    DEFF Research Database (Denmark)

    Lund, Mia Schou Møller; Kevern, John T.; Schaefer, Vernon R.

    2017-01-01

    Pearl-Chain Bridges are an innovative precast arch bridge technology which can utilize pervious concrete as fill material. The present study investigates how the mix design of the pervious concrete fill can be influenced by use of an air-entraining admixture, a high-range water reducing admixture......, fibers, and by internal curing using lightweight aggregate to best possibly meet the requirements for a fill material in Pearl-Chain Bridges. The 28-day compressive strength, splitting tensile strength, shear strength, permeability, and freeze-thaw durability were determined and compared for eight...... different mixture proportions using two different sizes of granite coarse aggregate and at two different water-to-cement ratios. The specimens had an average void content of 24-28 %. Specimens containing air entraining and high-range water reducing admixtures were most workable, as determined by fresh...

  12. The Arctic Vegetation Type Change retrieved from Spaceborne Observations and its Influence on the Simulation of Permafrost Thawing

    Science.gov (United States)

    Kim, Y.; Wang, Z.

    2017-12-01

    The vegetation types change in Arctic has been studied using 10 years of MODIS land cover product (MCD12Q1). The shrub expansion is observed in Alaska and Northeast Asia, while shrub fraction decreases in North Canada and Southwest Arctic Eurasia. The total Arctic shrub fraction increases 3% in 10 years. The tundra decreases where the shrub expands, and thrives where the shrub retreats. In order to isolate the influence of the vegetation dynamic on the permafrost thawing, the Arctic terrestrial ecosystem in recent decades will be simulated using the Community Land Model (CLM) with and without the vegetation type changes. The energy and carbon exchange on the land surface will also be simulated and compared. Acknowledgement: This work was supported by the Korea Polar Research Institute (KOPRI, PN17081) and the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (2015R1C1A2A01054800).

  13. EFFECTS OF A NEW ANTIBIOTIC COMBINATION ON POST -THAW MOTION CHRACTERISTICS AND MEMBRANE INTEGRITY OF BUFFALO AND SAHIWAL BULL SPERMATOZOA AND ON THE BACTERIOLOGICAL QUALITY OF THEIR SEMEN

    Directory of Open Access Journals (Sweden)

    S. Hasan, S. M. H. Andrabi, R. Muneer, M. Anzar and N. Ahmad

    2001-01-01

    Full Text Available In this study the effects of a new antibiotic combination, i.e., gentamycin, tylosin and linco-spectin (STLS on post-thaw motion characteristics, plasma membrane integrity, sperm morphology and the total aerobic bacterial counts (TABC in buffalo and Sahiwal bull semen were investigated. Ten ejaculates, five each from a buffalo and a Sahiwal bull, possessing more than 60% sperm motility were used. These ejaculates were diluted in Tris-citric acid (TCA extender (at 37 °C; 50 X 106 spermatozoa/mi, containing either GTLS (gentamycin 500 g/ml, tylosin 100 g/ml and linco-spectin 300/600 g/ml, streptomycin 1000 g/ml and penicillin 1000 IU/ml (SP, or negative control with no antibiotics (NCON. Samples were cooled to 4°C in 2 hours, equilibrated at 4°C for 4 hours, filled in 0.5 ml straws, frozen in a controlled rate cell freezer and plunged into liquid nitrogen. Frozen semen was thawed at 37°C for 15 seconds. Post-thaw sperm motion characteristics, plasma membrane integrity and sperm morphology were determined. Total aerobic bacterial counts and the frequency of appearance of bacterial genera were determined in neat semen, after dilution, and after freezing and thawing. Mean motilities (visual; computer-assisted, linear and circular, velocities (straight-line, average path and curvilinear and lateral head displacement (LHD in post- thaw semen samples did not differ due to antibiotics or species. Same was true for sperm plasma membrane integrity. Morphologically abnormal spermatozoa were lower (P<0.05 in GTLS and SP than in NCON. Sperm cells possessing normal acrosomes were higher (P<0.01 in GTLS and SP than in NCON. Total aerobic bacterial counts in post-thaw samples were lower (P<0.05 in GTLS than in SP or NCON. Staphylococcus and micrococcus were lower in samples treated with GTLS than that of SP or NCON. Pseudomonas and E.coli were more frequent in buffaloes than Sahiwal bull samples. Proteus and corynebacteria were scarcely present

  14. Consequences of uncontrolled cooling during sterlet (Acipenser ruthenus) sperm cryopreservation on post-thaw motility and fertilizing ability.

    Science.gov (United States)

    Horokhovatskyi, Yevhen; Rodina, Marek; Asyabar, Hadiseh Dadras; Boryshpolets, Sergii; Dzyuba, Borys

    2017-06-01

    The significant influence of the number and position of fish sperm sample straws in uncontrolled cooling devices on post-thaw spermatozoa parameters, such as motility and fertilizing ability, is presented in this study. The two most popular uncontrolled cooling devices were used in this study: a Styrofoam box setup with a polystyrene floating raft on liquid nitrogen and the dry shipper setup with a straw holder. We tested the effect of different quantities of straws (6 or 60) placed on the polystyrene floating raft and the position of the straws in the holder (on the periphery or in the centre). Using these cooling methods, sperm of 10 male sterlets diluted with methanol containing cryoprotective medium was frozen. All temperature changes were recorded by a thermocouple inside the straw, and the thermogram intervals were analysed. Spermatozoa motility was evaluated by video microscopy with integrated computer-assisted sperm analysis software. Fertilization trials were conducted at a 10 5 spermatozoa/egg ratio. Post-thaw spermatozoa parameters, including the percent of motile spermatozoa, curvilinear velocity, velocity according to the smoothed path, linearity of track, beat-cross frequency and fertilization rate, were significantly decreased in the 60-straw floating raft setup in comparison to all of the other cooling methods. The freezing rate between -10 °C and -30 °C was significantly decreased by up to 18.6 ± 0.61 °C/min for the 60-straw floating raft setup in comparison to the other freezing conditions. Considering the above results, efforts to standardize cryopreservation protocols using uncontrolled cooling devices should take into account the amount of straws subjected to freezing. Copyright © 2017. Published by Elsevier Inc.

  15. Comparison of endoscopic-assisted transcervical and laparotomy insemination with frozen-thawed dog semen: a retrospective clinical study.

    Science.gov (United States)

    Mason, S J; Rous, N R

    2014-10-01

    The objective of this retrospective clinical study was to compare pregnancy rates obtained after the use of endoscopic-assisted transcervical cathet