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Sample records for em beltsville thawing

  1. The effects of different levels of vitamin E and vitamin C 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

    2015-12-01

    Oxidative damage of sperm by means of reactive oxygen species generated by the cellular components of semen is one of the main reason of declined motility and fertility of sperm during the freeze-thawing process. This study was conducted to determine the influence of vitamin C and vitamin E on rooster post-thawed sperm motility, viability and malondialdehyde (MDA) level. 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 with no antioxidants (control), or containing 100 (C100), 200 (C200), 400 (C400), 800 (C800) µg/mL vitamin C, and 2 (E2), 5 (E5), 10 (E10) and 15 (E15) µg/mL vitamin E. After thawing, total and progressive sperm motility, sperm viability and semen MDA level were assessed. The results shown that C200 and E5 extenders resulted in higher total motility (p rooster spermatozoa.

  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 (Prooster semen. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Comparative evaluation of Nabi and Beltsville extenders for cryopreservation of rooster semen.

    Science.gov (United States)

    Nabi, Mohammad Mahdi; Kohram, Hamid; Zhandi, Mahdi; Mehrabani-Yeganeh, Hassan; Sharideh, Hossein; Zare-Shahaneh, Ahmad; Esmaili, Vahid

    2016-02-01

    Two experiments were conducted to evaluate the new rooster semen freezing extender which is containing a low level of glycerol and soybean lecithin as an alternative protective agent in the extender. The aim of the first experiment was to evaluate a new extender for freeze-thawing rooster semen known as "Nabi" extender compared to Beltsville. Second experiment was also performed to determine whether the Nabi extender has negative reactions on fertilization after artificial insemination (AI) or no. In the first experiment, post-thaw motion parameters, mitochondrial function and sperm apoptosis were analyzed using Sperm Class Analyzer (SCA), rhodamine-123 and Annexin-V, respectively for frozen-thawed semen in Nabi and Beltsville extender. Results showed that total motility, progressive motility, velocity parameters (VCL, VSL, VAP, LIN and STR) and live spermatozoa with active mitochondria were significantly higher in Nabi compare to Beltsville extender (P rooster sperm in vitro quality compared to Beltsville extender. The fertility rates of insemination in hens with freeze-thaw sperm were comparable with fresh sperm. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Effects of adding different levels of Glutamine to modified Beltsville extender on the survival of frozen rooster semen.

    Science.gov (United States)

    Khiabani, Aytak Bakhshayesh; Moghaddam, Gholamali; Kia, Hossein Daghigh

    2017-09-01

    The aim of the present study was to investigate the effects of l-glutamine on the quality of frozen-thawed rooster semen. Semen samples were collected from eight mature roosters (Ross 308). After initial semen assessments, samples of adequate quality were mixed together and diluted with modified Beltsville extender without l-glutamine (control) and supplemented with 2.5, 5, and 7.5mM l-glutamine. Semen straws were subjected to cryopreservation and evaluated twice at 15-day intervals. After thawing, sperm viability, total and progressive sperm motilities were measured by Eosin-Nigrosine and Computer-Aided Sperm Analysis (CASA), respectively. The results showed that sperm functions decreased on day 30 compared to day 15. The extender supplemented with 5mM glutamine improved (prooster sperm to be frozen for longer. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. DESCRIPTION OF ULTRASTRUCTURAL DAMAGES IN FROZEN-THAWED CANINE SPERMATOZOA DESCRIÇÃO DE DANOS ULTRAESTRUTURAIS EM ESPERMATOZOIDES CANINOS CONGELADOS-DESCONGELADOS

    Directory of Open Access Journals (Sweden)

    Viviane Helena Chirinéa

    2009-07-01

    Full Text Available In spite of the advances in transmission electronic microscopy (TEM, there are few studies presenting a systematic description of the canine spermatozoa and they are only focused on sperm cell heads. The goal of the present study was to describe ultrastructural appearance of canine fresh and frozen-thawed spermatozoa, focusing on damages induced by freezing-thawing in different sperm regions. Ten ejaculates from five proven stud dogs (two ejaculates/dog were collected, evaluated, extended in Tris-egg yolk-glycerol, frozen and stored in liquid nitrogen, and thawed six weeks later.  Samples were evaluated for progressive motility, morphology, and for ultrastructural analysis by TEM. Concerning to TEM, the most striking differences between fresh and frozen-thawed samples were observed over the mid-piece since the fresh spermatozoa showed a well preserved mid-piece. However, the frozen-thawed spermatozoa mid-piece showed signs of damage such as mitochondrial vacuolization. In conclusion, freezing-thawing processes using a Tris-egg yolk extender induce ultrastructural damages in head and mid-piece of canine sperm, affecting the mitochondrial ultrastructure besides.

    KEY WORDS: Cryopreservation, dog, semen, ultrastructure.
    Apesar dos avanços na microscopia eletrônica de transmissão (MET, existem poucos estudos apresentando uma descrição sistemática do espermatozoide canino, os quais estão focados apenas na cabeça espermática. Objetivou-se, com o presente estudo, descrever a aparência ultraestrutural do espermatozoide canino fresco e congelado-descongelado, enfocando os danos induzidos pela congelação e descongelação em diferentes regiões espermáticas. Dez ejaculados obtidos de cinco cães (dois ejaculados por cão foram coletados, avaliados e diluídos em Tris-gema-glicerol, congelados e armazenados em nitrogênio líquido, e descongelados seis semanas após. Avaliaram-se as amostras quanto à motilidade progressiva

  6. Hyaluronic acid improves frozen-thawed sperm quality and fertility potential in rooster.

    Science.gov (United States)

    Lotfi, Saied; Mehri, Morteza; Sharafi, Mohsen; Masoudi, Reza

    2017-09-01

    Beneficial effects of Hyaluronic acid (HA) has not been yet assessed for cryopreservation of rooster sperm. This study was conducted to evaluate the effects of different concentrations of HA (0, 1, 2, 4 and 8mM) in Beltsville extender on the cryopreservation of rooster sperm. Semen samples were collected from six Ross broiler breeders (24-week) using abdominal massage, then divided into five equal aliquots and cryopreserved in Beltsville extender that contained different concentrations of HA. Motion characteristics, morphology, membrane functionality, viability, acrosome integrity, lipid peroxidation and fertility potential of sperm were assessed after thawing. HA at concentration of 2mM (HA2) resulted in the highest (Prooster sperm after freeze thawing. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Fertility and flow cytometric evaluations of frozen-thawed rooster semen in cryopreservation medium containing low-density lipoprotein.

    Science.gov (United States)

    Shahverdi, A; Sharafi, M; Gourabi, H; Yekta, A Amiri; Esmaeili, V; Sharbatoghli, M; Janzamin, E; Hajnasrollahi, M; Mostafayi, F

    2015-01-01

    Frozen-thawed rooster semen is not reliable for use in artificial insemination in commercial stocks. Low-density lipoprotein (LDL) has been assessed for effectiveness as a cryoprotectant in the extender to improve the quality of frozen-thawed rooster semen. Although LDL has been evaluated in a few studies in other species for semen cryopreservation, so far no study has been conducted to examine this cryoprotectant for cryopreservation of fowl semen. Thus, this study aims to analyze the effects of different concentrations of LDL (0%, 2%, 4%, 6%, and 8%) in a Beltsville extender for cryopreservation of rooster spermatozoa. In experiment 1, motion parameters, membrane integrity, acrosome integrity, apoptosis status, and mitochondria activity were assessed after freeze-thawing. The highest quality frozen-thawed semen was selected to be used for evaluation of the fertility rate in experiment 2. Semen was collected from six roosters, twice weekly, then extended in a Beltsville extender that contained different concentrations of LDL as follows: 0% (control), 1% (Beltsville plus 1% LDL [BLDL1]), 2% (BLDL2), 4% (BLDL4), 6% (BLDL6), and 8% (BLDL8). Supplementation of the Beltsville extender with 4% LDL produced the most significant percentage of motility (43.1 ± 1.3), membrane integrity (59.4 ± 2.1),mitochondria activity (49.1 ± 1.19), and viable spermatozoa (45 ± 2.28) compared with the control treatment with the results of 22.7 ± 1.3 (motility), 38.4 ± 2.1 (membrane integrity), 40.25 ± 1.19 (mitochondrial activity), and 37.8 ± 2.28 (viability). In experiment 2, a significantly higher percentage of fertility rate was observed for frozen-thawed semen in the extender supplemented with 4% LDL (49.5 ± 1.6) compared with the control (29.2 ± 2.9). Progressive motility and acrosome integrity were not affected by LDL levels in the extenders. The results revealed that supplementation of the Beltsville extender with 4% LDL resulted in higher quality of frozen-thawed rooster

  8. Transferência de blastocisto após descongelamento de embriões em mórula resultando em gestação gemelar: relato de caso Twin pregnancy after thawing of morula embryos and blastocyst transfer: case report

    Directory of Open Access Journals (Sweden)

    Luiz Eduardo T. Albuquerque

    1999-12-01

    Full Text Available A criopreservação de embriões em estágios mais tardios do desenvolvimento parece apresentar resultados satisfatórios. Com o objetivo de melhor testar a sobrevivência e o desenvolvimento de embriões, os mesmos foram criopreservados e descongelados em estadio de mórula ou blastocisto e deixados em cultura para que pudesse ser avaliada sua evolução natural. Dos 2 blastocistos e 5 mórulas congelados, 4 mórulas sobreviveram ao descongelamento, tendo sido transferidas em estadio de blastocisto, 24 horas depois. A transferência, realizada em paciente jovem, segundo casamento de homem vasectomizado há dez anos, resultou em gestação gemelar. O descongelamento de embriões em estadio de mórula e a observação in vitro da retomada de seu desenvolvimento até o estadio de blastocisto fornecem um parâmetro adicional na avaliação da qualidade do embrião e, provavelmente, melhore as taxas de gravidez.The cryopreservation of embryos in late developing stages seems to present satisfactory results. With the purpose of better testing the embryos' survival, they were cryopreserved in the morula or blastocyst stage, thawed and left in culture for 24 hours so that their natural evolution could be observed. Amongst the frozen 2 blastocysts and 5 morulas, 4 morulas survived the thawing process, being transferred as blastocysts 24 hours later. The transfer was performed in a young patient, second marriage of a ten-year vasectomized man and resulted in twin pregnancy. Thawing morula embryos and the in vitro observation of their development resumption until the blastocyst stage give us an additional parameter in the quality evaluation of the embryo and probably an improvement in pregnancy rates.

  9. Defined Combinations of Cryomedia and Thawing Extenders Influence the Viable X-Y Boar Sperm Ratio in Vitro.

    Science.gov (United States)

    Korchunjit, W; Kaeoket, K; Kitiyanant, Y; Taylor, J; Wongtawan, T

    It is believed that plasma membrane X- and Y-chromosome bearing sperm are different; therefore the freezing and thawing process may affect X- and Y-sperm differently. The objective of this study was to investigate the effect of cryomedia and thawing extenders on the survival of X and Y-sperm. Three different cryomedia and thawing extenders were compared. Viable motile sperm were separated using a swim-up technique. Real-time PCR was used to identify the sperm type. Using CryoA for freezing and Beltsville-Thawing-Solution (BTS) as the thawing extender yielded significantly higher numbers of viable motile Y sperm (64 percent) than control (48 percent) (P semen freezing with CryoC and thawing with Androstar Plus gave a significantly lower number of viable motile Y sperm (32 percent) than control (51 percent). Our results revealed that defined combinations of cryomedia and thawing extenders significantly altered the survival ratio of frozen-thawed X-Y sperm in vitro, which has potential implications for artificial insemination.

  10. Addition of cholesterol-loaded cyclodextrins to the thawing extender: effects on boar sperm quality.

    Science.gov (United States)

    Tomás, C; Gómez-Fernández, J; Gómez-Izquierdo, E; Mocé, E; de Mercado, E

    2014-06-01

    The aim of the present study was to evaluate the effect that the addition of cholesterol-loaded cyclodextrins (CLC) to the thawing extender has on the quality of frozen-thawed boar sperm. Pooled semen (n = 5) from three boars was used for the experiments. The semen was cryopreserved with an egg-yolk-based extender, it was diluted after thawing in Beltsville thawing solution (BTS) supplemented with different concentrations of CLC (0, 12.5, 25, 50 or 100 mg/500 × 10(6) sperm), and these samples were incubated at 37°C for 150 min. The following parameters of sperm quality were evaluated 30 and 150 min after incubation: sperm with intact plasma membrane (SIPM; %), sperm with normal acrosomal ridge (NAR; %), total motile sperm (TMS; %), progressively motile sperm (PMS; %) and kinetic parameters. Both SIPM and NAR increased (p extender was supplemented with 12.5, 25 and 50 mg CLC/500 × 10(6) sperm. Nevertheless, motility decreased (p extenders with CLC improves sperm viability and reduces acrosome damage after freezing/thawing. © 2014 Blackwell Verlag GmbH.

  11. L-Carnitine in rooster semen cryopreservation: Flow cytometric, biochemical and motion findings for frozen-thawed sperm.

    Science.gov (United States)

    Fattah, A; Sharafi, M; Masoudi, R; Shahverdi, A; Esmaeili, V; Najafi, A

    2017-02-01

    Rooster semen cryopreservation is not efficient for artificial insemination in breeder flocks. L-Carnitine (LC) has been evaluated for effectiveness in cryopreservation media on the characteristics of rooster sperm after freeze-thawing. Motility characteristics, membrane functionality, abnormal morphology, apoptotic like changes, mitochondria activity and lipid peroxidation of rooster sperms were assessed after freeze-thawing with different concentrations of LC in Beltsville medium. Semen samples were collected from 12 roosters, twice a week, and diluted in the extenders that contained different concentrations of LC. Supplementation of Beltsevile with 1 and 2 mM LC was found to result in higher total motility (68.2± 1.7% and 69.1± 1.7%, respectively), progressive motility (28.4± 1.6%, 29.8± 1.6%), membrane functionality (76.2± 1.9% and 75.9± 1.9%), viability (58.2 ± 1.1%, 59.1 ± 1.1%) and lower significant of lipid peroxidation (2.53 ± 0.08 nmol/ml, 2.49 ± 0.08 nmol/ml) compared to control group containing no LC. Lower motility, progressive motility, and viability were observed in frozen-thawed sperm in extender containing 8 mM LC (35.8± 1.7%, 9.6± 1.2% and 27.1 ± 1.2%, respectively) compared to control. Morphology and mitochondrial activity were not affected by different concentrations of LC. Our results showed that supplementation of Beltsville extender with 1 and 2 mM LC significantly improved the quality of rooster sperm quality after freeze-thawing. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Thawing of Frozen Tuna Meat

    Science.gov (United States)

    Tanaka, Takeo; Nishiwaki, Kôji; Kakuda, Kitonari; Tomimatsu, Takao

    Frozen southern bluefin tuna meat discolors easily and sometimes contracts when thawed caused by thaw rigor. These phenomenon often become problematic in the transaction or handling of this kind of frozen tuna. Frozen meat blocks of southern Bluefin tuna were thawed separately by air thawing, running water thawing and microwave thawing. Changes occurring during thawing were checked for meat color by met-myoglobin ratio determination and for contract by microscopic observation. Results are as follows : (1) Discoloration scarcely occurred in the process of running water thawing (at 10°C for 50 min, or at 0°C for 6 hr). (2) No contraction was observed during thawing with running water described above and air thawing (at 18-20°C for 6 hr). (3) Discoloration and contraction seemed to be minimized, as to latently contractile blocks, when meat temperature passed through rapidly between -10°C and -5°C, and slowly (for 5-6 hr) between -5°C and -1°C. When the block was originally not contractile, discloration was minimized by rising meat temperature rapidly from -10°C to -l°C.

  13. Control of water infiltration into near surface low-level waste disposal units. Final report on field experiments at a humid region site, Beltsville, Maryland

    International Nuclear Information System (INIS)

    Schulz, R.K.; Ridky, R.W.; O'Donnell, E.

    1997-09-01

    This study''s objective was to assess means for controlling water infiltration through waste disposal unit covers in humid regions. Experimental work was carried out in large-scale lysimeters 21.34 m x 13.72 m x 3.05 m (70 ft x 45 ft x 10 ft) at Beltsville, Maryland. Results of the assessment are applicable to disposal of low-level radioactive waste (LLW), uranium mill tailings, hazardous waste, and sanitary landfills. Three kinds of waste disposal unit covers or barriers to water infiltration were investigated: (1) resistive layer barrier, (2) conductive layer barrier, and (3) bioengineering management

  14.   Ultrasonic monitoring of fish thawing process optimal time of thawing and effect of freezing/thawing.

    Science.gov (United States)

    El Kadi, Youssef Ait; Moudden, Ali; Faiz, Bouazza; Maze, Gerard; Decultot, Dominique

    2013-01-01

    Fish quality is traditionally controlled by chemical and microbiological analysis. The non-destructive control presents an enormous professional interest thanks to the technical contribution and precision of the analysis to which it leads. This paper presents the results obtained from a characterisation of fish thaw-ing process by the ultrasonic technique, with monitoring thermal processing from frozen to defrosted states. The study was carried out on fish type red drum and salmon cut into fillets of 15 mm thickness. After being frozen at -20°C, the sample is enclosed in a plexiglas vessel with parallel walls at the ambient temperature 30°C and excited in perpendicular incidence at 0.5 MHz by an ultrasonic pulser-receiver Sofranel 5052PR. the technique of measurement consists to study the signals reflected by fish during its thawing, the specific techniques of signal processing are implemented to deduce informations characterizing the state of fish and its thawing process by examining the evolution of the position echoes reflected by the sample and the viscoelastic parameters of fish during its thawing. The obtained results show a relationship between the thermal state of fish and its acoustic properties, which allowed to deduce the optimal time of the first thawing in order to restrict the growth of microbial flora. For salmon, the results show a decrease of 36% of the time of the second thawing and an increase of 10.88% of the phase velocity, with a decrease of 65.5% of the peak-to-peak voltage of the signal reflected, thus a decrease of the acoustic impedance. This study shows an optimal time and an evolution rate of thawing specific to each type offish and a correlation between the acoustic behavior of fish and its thermal state which approves that this technique of ultrasonic monitoring can substitute the control using the destructive chemical analysis in order to monitor the thawing process and to know whether a fish has suffered an accidental thawing.

  15. 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.

  16. To transfer fresh or thawed embryos?

    DEFF Research Database (Denmark)

    Pinborg, Anja

    2012-01-01

    Worldwide freezing and thawing of embryos has been increasingly used since the first infant was born as a result of this technique in 1984. The use of frozen embryo replacement (FER) currently even exceeds the number of fresh cycles performed in some countries. This article discusses the pros...... and multiple pregnancies, thereby increasing the safety for mother and child. Finally the article describes the accumulating literature on perinatal and long-term child outcome after transfer of frozen/thawed embryos, including a discussion on the concerns regarding cryo techniques and their possible roles...

  17. Improved Performance of Unpaved Roads During Spring Thaw

    National Research Council Canada - National Science Library

    Henry, Karen S; Olson, James P; Farrington, Stephen P; Lens, John

    2005-01-01

    Unpaved roads in Vermont are subject to deterioration from seasonal freezing and thawing, and many towns have roads that suffer chronic serviceability problems during the so-called "spring thaw," or mud season...

  18. 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...

  19. Control of water infiltration into near surface LLW disposal units. Progress report on field experiments at a humid region site, Beltsville, Maryland: Volume 7

    International Nuclear Information System (INIS)

    Schulz, R.K.; Ridky, R.W.; O'Donnell, E.

    1994-12-01

    The project objective is to assess means for controlling waste infiltration through waste disposal unit covers in humid regions. Experimental work is being performed in large scale lysimeters (70 ft x 45 ft x 10 ft) at Beltsville, MD and results of the assessment are applicable to disposal of LLW, uranium mill tailings, hazardous waste, and sanitary landfills. Three concepts are under investigation: (1) resistive layer barrier, (2) conductive layer barrier, and bioengineering water management. The resistive layer barrier consists of compacted earth (clay). The conductive layer barrier is a special case of the capillary barrier and it requires a flow layer (e.g. fine sandy loam) over a capillary break. As long as unsaturated conditions are maintained water is conducted by the flow layer to below the waste. This barrier is most efficient at low flow rates and is thus best placed below a resistive layer barrier. Such a combination of the resistive layer over the conductive layer barrier promises to be highly effective provided there is no appreciable subsidence. Bioengineering water management is a surface cover that is designed to accommodate subsidence. It consists of impermeable panels which enhance run-off and limit infiltration. Vegetation is planted in narrow openings between panels to transpire water from below the panels. This system has successfully dewatered two lysimeters thus demonstrating that this procedure could be used for remedial action (drying out) existing water-logged disposal sites at low cost

  20. Control of water infiltration into near surface LLW disposal units - progress report on field experiments at a Humid Region Site, Beltsville, Maryland

    International Nuclear Information System (INIS)

    O'Donnell, E.; Ridky, R.W.; Schulz, R.K.

    1990-01-01

    Three kinds of waste disposal unit covers or barriers to water infiltration are being investigated. They are: (1) resistive layer barrier, (2) conductive layer barrier, and (3) bioengineering management. The resistive layer barrier consists of compacted earthen material (e.g. clay). The conductive layer barrier consists of a conductive layer in conjunction with a capillary break. As long as unsaturated flow conditions are maintained the conductive layer will wick water around the capillary break. Below grade layered covers such as (1) and (2) will fail if there is appreciable subsidence of the cover. Remedial action for this kind of failure will be difficult. A surface cover, called bioengineering management, is meant to overcome this problem. The bioengineering management surface barrier is easily repairable if damaged by subsidence; therefore, it could be the system of choice under active subsidence conditions. The bioengineering management procedure also has been shown to be effective in dewatering saturated trenches and could be used for remedial action efforts. After cessation of subsidence, that procedure could be replaced by a resistive layer barrier, or perhaps even better, a resistive layer barrier/conductive layer barrier system. This latter system would then give long-term effective protection against water entry to waste and without institutional care. These various concepts are being assessed in six large (70 x 45 x 10 each) lysimeters at Beltsville, Maryland. 6 refs., 21 figs

  1. Control of water infiltration into near surface LLW disposal units. Progress report on field experiments at a humid region site, Beltsville, Maryland: Volume 8

    International Nuclear Information System (INIS)

    Schulz, R.K.; Ridky, R.W.

    1995-04-01

    This study's objective is to assess means for controlling water infiltration through waste disposal unit covers in humid regions. Experimental work is being performed in large-scale lysimeters 21.34 m x 13.72 m x 3.05 m (75 ft x 45 ft x 10 ft) at Beltsville, Maryland. Results of the assessment are applicable to disposal of low-level radioactive waste (LLW), uranium mill tailings, hazardous waste, and sanitary landfills. Three kinds of waste disposal unit covers or barriers to water infiltration are being investigated: (1) resistive layer barrier, (2) conductive layer barrier, and (3) bioengineering management. The resistive layer barrier consists of compacted earthen material (e.g., clay). The conductive layer barrier consists of a conductive layer in conjunction with a capillary break. As long as unsaturated flow conditions are maintained, the conductive layer will wick water around the capillary break. Below-grade layered covers such as (1) and (2) will fail if there is appreciable subsidence of the cover, and remedial action for this kind of failure will be difficult. A surface cover, called bioengineering management, is meant to overcome this problem. The bioengineering management surface barrier is easily repairable if damaged by subsidence; therefore, it could be the system of choice under active subsidence conditions. The bioengineering management procedure also has been shown to be effective in dewatering saturated trenches and could be used for remedial action efforts. After cessation of subsidence, that procedure could be replaced by a resistive layer barrier or, perhaps even better, by a resistive layer barrier/conductive layer barrier system. The latter system would then give long-term effective protection against water entry into waste without institutional care

  2. Control of water infiltration into near surface LLW disposal units: Progress report on field experiments at a humid region site, Beltsville, Maryland

    International Nuclear Information System (INIS)

    Schulz, R.K.; Ridky, R.W.

    1996-08-01

    This study's objective is to assess means for controlling water infiltration through waste disposal unit covers in humid regions. Experimental work is being performed in large-scale lysimeters 21.34 m x 13.72 m x 3.05 m (70 ft x 45 ft x 10 ft) at Beltsville, Maryland. Results of the assessment are applicable to disposal of low-level radioactive waste (LLW), uranium mill tailings, hazardous waste, and sanitary landfills. Three kinds of waste disposal unit covers or barriers to water infiltration are being investigated: (1) resistive layer barrier, (2) conductive layer barrier, and (3) bioengineering management. The resistive layer barrier consists of compacted earthen material (e.g., clay). The conductive layer barrier consists of a conductive layer in conjunction with a capillary break. As long as unsaturated flow conditions are maintained, the conductive layer will wick water around the capillary break. Below-grade layered covers such as (1) and (2) will fail if there is appreciable subsidence of the cover, and remedial action for this kind of failure will be difficult. A surface cover, called bioengineering management, is meant to overcome this problem. The bioengineering management surface barrier is easily repairable if damaged by subsidence; therefore, it could be the system of choice under active subsidence conditions. The bioengineering management procedure also has been shown to be effective in dewatering saturated trenches and could be used for remedial action efforts. After cessation of subsidence, that procedure could be replaced by a resistive layer barrier or, perhaps even better, by a resistive layer barrier/conductive layer barrier system. The latter system would then give long-term effective protection against water entry into waste without institutional care

  3. Control of water infiltration into near surface LLW disposal units-progress report on field experiments at a humid region site, Beltsville, Maryland

    International Nuclear Information System (INIS)

    O'Donnell, E.; Ridky, R.W.; Schulz, R.K.

    1994-01-01

    The study's objective is to assess means for controlling water infiltration through waste disposal unit covers in humid regions. Experimental work is being performed in large-scale lysimeters (75'x45'x10') at Beltsville, MD, and results of the assessment are applicable to disposal of low-level radioactive waste (LLW), uranium mill tailings, hazardous waste, and sanitary landfills. Three kinds of waste disposal unit covers or barriers to water infiltration are being investigated. They are: (1) resistive layer barrier, (2) conductive layer barrier, and (3) bioengineering management. The conductive layer barrier consists of a conductive layer in conjunction with a capillary break. As long as unsaturated flow conditions are maintained, the conductive layer will wick water around the capillary break. Below-grade layered covers such as (1) and (2) will fail if there is appreciable subsidence of the cover. Remedial action for this kind of failure will be difficult. A surface cover, called bioengineering management, is meant to overcome this problem. The bioengineering management surface barrier is easily repairable if damaged by subsidence; therefore, it could be the system of choice under active subsidence conditions. The bioengineering management procedure also has been shown to be effective in dewatering saturated trenches and could be used for remedial action efforts. After cessation of subsidence, that procedure could be replaced by a resistive layer barrier, or perhaps even better, a resistive layer barrier/conductive layer barrier system. This latter system would then give long-term effective protection against water entry into waste and without institutional care

  4. Use of boar spermatozoa for artificial insemination. III. Fecundity of boar spermatozoa stored in Beltsville liquid and Kiev extenders for three days at 18 C.

    Science.gov (United States)

    Johnson, L A; Aalbers, J G; Willems, C M; Rademaker, J H; Rexroad, C E

    1982-01-01

    A field trial was conducted on several hundred farms in The Netherlands to compare the fertilizing capacity of boar spermatozoa stored for 1, 2, or 3 d at 18 C in either Kiev or Beltsville liquid extender (BL-1). Two storage volumes (25 and 100 ml) were used. Twelve Dutch Landrace boars, all in routine commercial artificial insemination service, provided the semen in twice-a-week collections. Over an 8-wk period in March and April, 1979, 2,849 sows and gilts were inseminated. Farrowing rates were higher (P less than .0001) with Kiev extender than with BL-1 extender (69.3 vs 60.5%) when semen was used over a 3 d period. The volume at which the semen was extended and stored had no effect on any parameter. Farrowing rate declined significantly when semen stored at 18 C for more than 2 d was used (74.5% vs 64.7% with semen stored for 1 and 3 in Kiev extender; 65.9% vs 52.7% with semen stored for 1 and 3 d in BL-1 extender). The farrowing rate, total number of pigs/litter and live pigs/litter were significantly higher for sows than for gilts inseminated with similar extended semen. On the basis of the results of this trial, Kiev extender appears to be more suitable as a diluent for liquid semen than does BL-1. AI with semen extended and stored for 3 d at 18 C can be expected to result in a lower farrowing rate than AI with semen stored for 1 or 2 d.

  5. Thaw flow control for liquid heat transport systems

    Science.gov (United States)

    Kirpich, Aaron S.

    1989-01-01

    In a liquid metal heat transport system including a source of thaw heat for use in a space reactor power system, the thaw flow throttle or control comprises a fluid passage having forward and reverse flow sections and a partition having a plurality of bleed holes therein to enable fluid flow between the forward and reverse sections. The flow throttle is positioned in the system relatively far from the source of thaw heat.

  6. Quality Evaluation of Pork with Various Freezing and Thawing Methods

    Science.gov (United States)

    2014-01-01

    In this study, the physicochemical and sensory quality characteristics due to the influence of various thawing methods on electro-magnetic and air blast frozen pork were examined. The packaged pork samples, which were frozen by air blast freezing at −45℃ or electro-magnetic freezing at −55℃, were thawed using 4 different methods: refrigeration (4±1℃), room temperature (RT, 25℃), cold water (15℃), and microwave (2450 MHz). Analyses were carried out to determine the drip and cooking loss, water holding capacity (WHC), moisture content and sensory evaluation. Frozen pork thawed in a microwave indicated relatively less thawing loss (0.63-1.24%) than the other thawing methods (0.68-1.38%). The cooking loss after electro-magnetic freezing indicated 37.4% by microwave thawing, compared with 32.9% by refrigeration, 36.5% by RT, and 37.2% by cold water in ham. The thawing of samples frozen by electro-magnetic freezing showed no significant differences between the methods used, while the moisture content was higher in belly thawed by microwave (62.0%) after electro-magnetic freezing than refrigeration (54.8%), RT (61.3%), and cold water (61.1%). The highest overall acceptability was shown for microwave thawing after electro-magnetic freezing but there were no significant differences compared to that of the other samples. PMID:26761493

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

    NARCIS (Netherlands)

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

    2011-01-01

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

  8. Discovery of a novel methanogen prevalent in thawing permafrost.

    Science.gov (United States)

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

    2014-01-01

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

  9. 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...

  10. 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.

  11. 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.

  12. Control of water infiltration into near surface LLW disposal units - Progress report on field experiments at a humid region site, Beltsville, Maryland

    Energy Technology Data Exchange (ETDEWEB)

    O' Donnell, Edward [U.S. Nuclear Regulatory Commission, Washington, DC (United States); Ridky, Robert W [University of Maryland, College Park, MD (United States); Schulz, Robert K [University of California, Berkeley, CA (United States)

    1992-07-01

    The study's objective is to assess means for controlling water infiltration through waste disposal unit covers in humid regions. Experimental work is being performed in large-scale lysimeters (75x45x10') at Beltsville, MD, and results of the assessment are applicable to disposal of low-level radioactive waste (LLW), uranium mill tailings, hazardous waste, and sanitary landfills. Three kinds of waste disposal unit covers or barriers to water infiltration are being investigated. They are: 1) resistive layer barrier, 2) conductive layer barrier, and 3) bioengineering management. The resistive layer barrier consists of compacted earthen material (e.g., clay). The conductive layer barrier consists of a conductive layer in conjunction with a capillary break. As long as unsaturated flow conditions are maintained, the conductive layer will wick water around the capillary break. Below-grade layered covers such as (1) and (2) will fail if there is appreciable subsidence of the cover. Remedial action for this kind of failure will be difficult. A surface cover, called bioengineering management, is meant to overcome this problem. The bioengineering management surface barrier is easily repairable if damaged by subsidence; therefore, it could be the system of choice under active subsidence conditions. The bioengineering management procedure also has been shown to be effective in dewatering saturated trenches and could be used for remedial action efforts. After cessation of subsidence, that procedure could be replaced by a resistive layer barrier, or perhaps even better, a resistive layer barrier/conductive layer barrier system. This latter system would then give long-term effective protection against water entry into waste and without institutional care. As mentioned in the preceding paragraph, a bioengineering management cover might well be the cover of choice during tho active subsidence phase of a waste disposal unit. Some maintenance is required during that period. Final

  13. Control of water infiltration into near surface LLW disposal units - Progress report on field experiments at a humid region site, Beltsville, Maryland

    International Nuclear Information System (INIS)

    O'Donnell, Edward; Ridky, Robert W.; Schulz, Robert K.

    1992-01-01

    The study's objective is to assess means for controlling water infiltration through waste disposal unit covers in humid regions. Experimental work is being performed in large-scale lysimeters (75x45x10') at Beltsville, MD, and results of the assessment are applicable to disposal of low-level radioactive waste (LLW), uranium mill tailings, hazardous waste, and sanitary landfills. Three kinds of waste disposal unit covers or barriers to water infiltration are being investigated. They are: 1) resistive layer barrier, 2) conductive layer barrier, and 3) bioengineering management. The resistive layer barrier consists of compacted earthen material (e.g., clay). The conductive layer barrier consists of a conductive layer in conjunction with a capillary break. As long as unsaturated flow conditions are maintained, the conductive layer will wick water around the capillary break. Below-grade layered covers such as (1) and (2) will fail if there is appreciable subsidence of the cover. Remedial action for this kind of failure will be difficult. A surface cover, called bioengineering management, is meant to overcome this problem. The bioengineering management surface barrier is easily repairable if damaged by subsidence; therefore, it could be the system of choice under active subsidence conditions. The bioengineering management procedure also has been shown to be effective in dewatering saturated trenches and could be used for remedial action efforts. After cessation of subsidence, that procedure could be replaced by a resistive layer barrier, or perhaps even better, a resistive layer barrier/conductive layer barrier system. This latter system would then give long-term effective protection against water entry into waste and without institutional care. As mentioned in the preceding paragraph, a bioengineering management cover might well be the cover of choice during tho active subsidence phase of a waste disposal unit. Some maintenance is required during that period. Final

  14. Permafrost Thaw increases Emissions of Nitrous Oxide from Subarctic Peatlands

    Science.gov (United States)

    Voigt, C.; Marushchak, M. E.; Lamprecht, R. E.; Jackowicz-Korczynski, M.; Lindgren, A.; Mastepanov, M.; Christensen, T. R.; Granlund, L.; Tahvanainen, T.; Martikainen, P. J.; Biasi, C.

    2017-12-01

    Permafrost soils in the Arctic are thawing, exposing not only carbon but also large nitrogen stocks. The decomposition of this vast pool of long-term immobile C and N stocks results in the release of greenhouse gases to the atmosphere. Among these, carbon dioxide (CO2) and methane (CH4) are being studied extensively, and gaseous C release from thawing permafrost is known to be substantial. Most recent studies, however, show that Arctic soils may further be a relevant source of the strong greenhouse gas nitrous oxide (N2O). As N2O is almost 300 times more powerful in warming the climate than CO2 based on a 100-yr time horizon, the release of N2O from thawing permafrost could create a significant non-carbon permafrost-climate feedback. To study the effect of permafrost thaw on N2O fluxes, we collected peat mesocosms from a Subarctic permafrost peatland, and subjected these intact soil-plant systems to sequential thawing from the top of the active layer down to the upper permafrost layer. Measurements of N2O fluxes were coupled with detailed soil analyses and process studies. Since N2O fluxes are highly dependent on moisture conditions and vegetation cover, we applied two distinct moisture treatments (dry vs. wet) and simulated permafrost thaw in vegetated as well as in naturally bare mesocosms. Under dry conditions, permafrost thaw clearly increased N2O emissions. We observed the largest post-thaw emissions from bare peat surfaces, a typical landform in subarctic peatlands previously identified as hot spots for Arctic N2O emissions. There, permafrost thaw caused a five-fold increase in emissions (0.56 vs. 2.81 mg N2O m-2 d-1). While water-logged conditions suppressed N2O emissions, the presence of vegetation lowered, but did not prevent post-thaw N2O release. Based on these findings, we show that one fourth of the Arctic land area could be vulnerable for N2O emissions when permafrost thaws. Our results demonstrate that Arctic N2O emissions may be larger than

  15. Breed differences of bull frozen-thawed semen.

    Science.gov (United States)

    Ntemka, A; Tsousis, G; Brozos, C; Kiossis, E; Boscos, C M; Tsakmakidis, I A

    2016-12-01

    The objective of this study was to investigate the quality of frozen-thawed semen from different bull breeds. Commercial frozen-thawed bull semen samples (26 per breed, 130 totally) of five breeds (Holstein [Η], Brown Swiss [BS], Limousin [L], Belgian Blue [BB], Blonde d' Aquitaine [BA]) were used. After thawing, each semen sample was subjected to thermal resistance test (TR) for 0.5 and 1 hr at 38°C and hypo-osmotic swelling test (HOST) for 1 hr at 150 mOsm at 37°C. Additionally, all samples were evaluated at times 0 hr (thawing), 0.5 hr (TR), 1 hr (TR) for kinetics by CASA [progressive, immotile, rapid, medium, slow moving spermatozoa, curvilinear velocity (VCL), average path velocity (VAP), straight line velocity (VSL), linearity (LIN), straightness (STR), beat cross-frequency (BCF), amplitude of lateral head displacement (ALH), wobble (WOB)]. Moreover, directly after thawing, all semen samples were evaluated for morphometry, morphology, viability and DNA fragmentation. Statistical analysis was conducted using a mixed model for repeated measures. The results showed (a) higher VCL after thawing in H, L breeds compared to BB and BA, (b) higher VAP after thawing in L compared to BB, BA, (c) higher values of progressive spermatozoa after TR in H, BS compared to BB, BA, (d) higher values of rapid spermatozoa after thawing and 0.5 hr of TR in H, BS, L compared to BB, BA, (e) lower viability in BA after thawing compared to H, BS, BB, (f) lower morphological abnormalities in H compared to L, BB, (g) higher head length in Η compared to BB. No significant differences were observed in the results from HOST and DNA fragmentation between breeds. In conclusion, quality characteristics of frozen-thawed bull semen are dependent on the breed. Frozen semen from BB and BA breeds should be handled more carefully after thawing, as it is more sensitive to stress. © 2016 Blackwell Verlag GmbH.

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

    Science.gov (United States)

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

    2014-01-01

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

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

    Directory of Open Access Journals (Sweden)

    MR Oliveira

    2015-06-01

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

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

    Science.gov (United States)

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

    2014-01-01

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

  19. 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.

  20. Thawing of lithium in the SP-100 reactor core configuration

    International Nuclear Information System (INIS)

    Magee, P.M.; Malovrh, J.W.; REineking, W.H.

    1986-01-01

    The General Electric SP-100 Liquid Metal Reactor is designed to be launched with the lithium coolant in the reactor and primary loops frozen. Initial startup of the system in space, after a satisfactory orbit is achieved, will be accomplished by slowly increasing the power in the reactor core and using the heat generated to melt the lithium, first in the reactor, and then progressively down the primary loops. This technique significantly facilitates ground handling, reduces vibrational loads during vehicle launch and minimized the shuttle bay heat load. The challenge is to thaw the coolant and startup the system within an acceptable time without structural damage. The test results clearly demonstrate that thawing of the lithium in the SP-100 reactor core can be done rapidly without structural damage and, thus, support the selected concept of SP-100 launch with frozen lithium and thaw/startup in space

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

    Science.gov (United States)

    Benli, Hakan

    2016-01-01

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

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

    Science.gov (United States)

    Benli, Hakan

    2016-01-01

    In this study, a survey was conducted to both evaluate the consumers’ general attitudes for purchasing and storing the raw chicken and determine the thawing practices used for defrosting frozen chicken at home. About 75% of the consumers indicated purchasing chicken meat at least once a week or more. Furthermore, the majority (82.16%) of those who stored at least a portion of the raw chicken stated freezing the raw chicken meat at home. Freezing the chicken meat was considered to have no effect on the quality by 43.49% of the consumers while 56.51% thought that freezing had either negative or positive effects on the quality. The survey study indicated that top five most commonly used thawing practices included thawing on the kitchen counter, thawing in the refrigerator, thawing in the warm water, thawing in the microwave, and thawing under tap water. In addition, an experimental study was conducted to determine the effects of these most commonly used thawing practices on some quality characteristics of the chicken meat including pH, drip loss, cooking loss, color analysis and textural profile analysis. Although, L* value for thawing on the kitchen counter was the lowest, after cooking, none of the thawing treatments have a significant effect on the color values. Thawing in the microwave produced the highest drip loss of 3.47% while the lowest drip loss of 0.62% was observed with thawing in the refrigerator. On the other hand, thawing in the microwave and refrigerator caused the lowest cooking loss values of 18.29% and 18.53%, respectively. Nevertheless, there were no significant differences among textural parameter values of the defrosted and then cooked samples using the home based thawing practices, indicating similar quality characteristics among the samples. PMID:26732333

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

    Directory of Open Access Journals (Sweden)

    Hakan Benli

    2016-01-01

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

  4. 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....

  5. High biolability of ancient permafrost carbon upon thaw

    NARCIS (Netherlands)

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

    2013-01-01

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

  6. Freeze-thaw resistance of concrete with marginal air content

    Science.gov (United States)

    2007-05-01

    Freeze-thaw resistance is a key durability factor for concrete pavements. Recommendations for the air void system parameters are normally 6 1 percent total air and a spacing factor of : < 0.20 millimeter (mm) (0.008 inch). However, it was observed...

  7. 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.

  8. High biolability of ancient permafrost carbon upon thaw

    NARCIS (Netherlands)

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

    2013-01-01

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

  9. Effect of freezing and thawing on UMTRA covers

    International Nuclear Information System (INIS)

    Rager, R.; Smith, G.; Brody, R.

    1988-01-01

    The proposed US Environmental Protection Agency (EPA) groundwater standards (40 CFR 192) require that Uranium Mill Tailings Remedial Action (UMTRA) Project remedial action designs meet low numerical limits for contaminants contained in water or vapor exiting the embankments. To meet the standards, a cover of compacted fine-grained soil is placed over UMTRA Project embankments. One of the functions of this cover is to limit infiltration. The hydraulic conductivity of this infiltration barrier must be low in order to reduce seepage from the cell to the extent necessary to comply with the proposed EPA groundwater standards. Analyses of infiltration barriers covered with rock erosion protection show that the infiltration barriers may become saturated. Accordingly, it is necessary to assure that freezing and thawing of the infiltration barrier materials do not affect the performance of the embankment. A study has been conducted to determine if the hydraulic conductivity of fine-grained clayey soils used or proposed for use in radon/infiltration barriers is affected by repeated freezing and thawing cycles. In addition, a procedure for determining the depth of frost penetration has been developed. Laboratory freeze-thaw tests were undertaken in order to determine if the saturated hydraulic conductivity of clay soils used in UMTRA Project radon/infiltration barriers was affected. The results indicate that an increase of an order of magnitude or more in saturated hydraulic conductivity may occur during repeated freeze-thaw cycles

  10. Freeze/thaw phenomena in concrete at low temperatures

    DEFF Research Database (Denmark)

    Johannesson, Björn

    2007-01-01

    Freeze/thaw damage in concrete is by general practice concluded to be a problem that can be avoided by using air-entraining agents to develop an air bubble structure in the hardened concrete together with the use of a relatively low water to cement ratio in mix. This fact is true for inner damage...

  11. Thawing and storage system for frozen food in the food service industries

    Energy Technology Data Exchange (ETDEWEB)

    Komada, Hitoshi; Tamura, Toshiyuki

    1988-02-01

    Thawing and storage system for frozen food in the food service industries was studied. The air flowing system was adequate for thawing owing to the convenience and quality retaining. Thawing time could not be reduced at 98% humidity and over 5/sup 0/C, even if the thawing temperature was elevated, and was lengthened at 5/sup 0/C or less. Further the thawing time could not be reduced by increasing the flowing speed at 1m/s or more. When the humidity was 65%, the thawing time was lengthened by 15%. The free drip was increased linearly with the increase of thawing temperature, so that a little higher thawing temperature than the frozen one was preferable. After the completion of thawing, the food was cooled suddenly in the pressing process to uniform the thawing and prevent the surface drip. Considering the structure decomposition and change, the storage temperature of -1/sup 0/C and the variation of +0.5/sup 0/C were desirable. The newly developed high humidity thawing cabinet resulted the better recovery of cell structure, less dripping amount and high quality thawing. A Super Chiller employing an inverter compressor resulted lower temperature variation and was effective for beef curing. (25 figs, 7 tabs, 4 refs)

  12. 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

  13. 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.

  14. Effect of freeze/thaw cycles on several biomarkers in urine from patients with kidney disease.

    Science.gov (United States)

    Zhang, Yinan; Luo, Yi; Lu, Huijuan; Wang, Niansong; Shen, Yixie; Chen, Ruihua; Fang, Pingyan; Yu, Hong; Wang, Congrong; Jia, Weiping

    2015-04-01

    Urine samples were collected from eleven randomly selected patients with kidney disease, including diabetic nephropathy, chronic nephritis, and nephritic syndrome. Urine samples were treated with one of four protocols for freezing and thawing: freeze directly and thaw directly; freeze directly and thaw by temperature gradient; freeze by temperature gradient and thaw directly; and freeze by temperature gradient and thaw by temperature gradient. After one to six freeze/thaw cycles at -20°C or -80°C, different biomarkers showed differential stabilities. The concentrations of total protein, calcium, and potassium did not change significantly after five freeze/thaw cycles at either -20°C or -80°C. Albumin could only sustain three freeze/thaw cycles at -20°C before it started to degrade. We recommend that urine be stored at -80°C as albumin and the organic ions could sustain five and six freeze/thaw cycles, respectively, using the simple "direct freeze and direct thaw" protocol. Furthermore, in most cases, gradient freeze/thaw cycles are not necessary for urine sample storage.

  15. 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.

  16. SHELF LIFE OF THAWED CRUSTACEANS TREATED WITH SULPHITES

    Directory of Open Access Journals (Sweden)

    G. Smaldone

    2011-04-01

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

  17. 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

  18. Cooking frozen and thawed roasts: beef, pork, and lamb cuts.

    Science.gov (United States)

    Fulton, C; Davis, C

    1975-09-01

    Cooking time, yield, and palatability of paired beef, pork, and lamb roasts cooked from the frozen and thawed states were compared. Cooking time for all roasts averaged from 3 to 22 min. per pound longer for meat cooked from the frozen state. The longer cooking time from the frozen state. The longer cooking time from the frozen state was greater for roasts with a large amount of bone and for cuts cooked by braising than for less bony roasts and cuts cooked by roasting. Except for thawed beef rump roasts, which had a higher yield of cooked lean meat, yield of cooked lean meat from the various cuts of beef, pork, and lamb was not affected by the state at the start of cooking. Collectively, all pork roasts had a higher yield of cooked lean meat when cooked from the frozen state. Juiciness and natural flavor of the roasts were not affected by the state at the start of cooking. Lamb leg and rib roasts were more tender when cooked from the thawed state.

  19. 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.

  20. Freeze-thaw-induced embolism in Pinus contorta: centrifuge experiments validate the 'thaw-expansion hypothesis' but conflict with ultrasonic emission data.

    Science.gov (United States)

    Mayr, Stefan; Sperry, John S

    2010-03-01

    *The 'thaw-expansion hypothesis' postulates that xylem embolism is caused by the formation of gas bubbles on freezing and their expansion on thawing. We evaluated the hypothesis using centrifuge experiments and ultrasonic emission monitoring in Pinus contorta. *Stem samples were exposed to freeze-thaw cycles at varying xylem pressure (P) in a centrifuge before the percentage loss of hydraulic conductivity (PLC) was measured. Ultrasonic acoustic emissions were registered on samples exposed to freeze-thaw cycles in a temperature chamber. *Freeze-thaw exposure of samples spun at -3 MPa induced a PLC of 32% (one frost cycle) and 50% (two cycles). An increase in P to -0.5 MPa during freezing had no PLC effect, whereas increased P during thaw lowered PLC to 7%. Ultrasonic acoustic emissions were observed during freezing and thawing at -3 MPa, but not in air-dried or water-saturated samples. A decrease in minimum temperature caused additional ultrasonic acoustic emissions, but had no effect on PLC. *The centrifuge experiments indicate that the 'thaw-expansion hypothesis' correctly describes the embolization process. Possible explanations for the increase in PLC on repeated frost cycles and for the ultrasonic acoustic emissions observed during freezing and with decreasing ice temperature are discussed.

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. Uso do diluente água de coco em pó (ACP-103® na conservação prolongada do sêmen do varrão: avaliação in vitro e in vivo Use of powder coconut water as extender (ACP-103® for boar semen longer preservation: in vitro and in vivo evaluations

    Directory of Open Access Journals (Sweden)

    R. Toniolli

    2010-10-01

    Full Text Available O sêmen de oito reprodutores foi coletado e de cada ejaculado separou-se um total de 1,75x10(9sptz, com concentração de 35x10(6sptz/mL. Usou-se o Beltsville Thawing Solution (BTS como controle para testar o diluente água de coco em pó (ACP. O dia de coleta foi o dia zero (D0, sendo o sêmen conservado durante cinco dias, com análises diárias no D0 e nos quatro dias seguintes (D1, D2, D3 e D4. A avaliação da qualidade espermática baseou-se nos resultados do vigor espermático, da porcentagem de células móveis, da morfologia espermática, da integridade da membrana plasmática e dos resultados de fertilidade. As avaliações do vigor espermático (4,1 e da porcentagem de espermatozoides móveis (91% ficaram acima dos parâmetros mínimos exigidos (3,0 e 70% para sua utilização em programas de inseminação artificial, pois não houve influência sobre as variáveis analisadas pelo protocolo experimental. O resultado médio da resistência osmótica foi de 71,3% de espermatozoides com cauda enrolada. Não houve diferenças entre os dois diluentes testados para a característica células com acrossoma intacto (BTS = 67,1%; ACP = 71,2%. O sêmen diluído em ACP apresentou maior número de células vivas (77,7 % com membrana plasmática íntegra (74,2% após a conservação. A escolha do diluente ACP é aconselhável para uso de rotina em laboratórios que trabalhem com conservação de sêmen suíno. Apesar dos bons resultados in vitro obtidos com o diluente ACP, o BTS apresentou os melhores resultados de fertilidade, 86,7% e 96,7%, respectivamente.The semen of eight boars was collected and a total of 1.75x10(9 spermatozoa were separated from each ejaculate, obtaining a concentration of 35x10(6sptz/mL. The Beltsville Thawing Solution (BTS was used as control, being tested the powder coconut water as extender (PCW. The day of collection was considered day zero (D0, and the semen was conserved for five days, with analyses on D0 and on

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

    OpenAIRE

    Chen, Yanlong; Wu, Peng; Yu, Qing; Xu, Guang

    2017-01-01

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

  7. Effect of Repeated Freeze-Thaw Cycles on Beef Quality and Safety

    Science.gov (United States)

    Rahman, Mohammad Hafizur; Hossain, Mohammad Mujaffar; Rahman, Syed Mohammad Ehsanur; Hashem, Mohammad Abul

    2014-01-01

    The objectives of this study were to know the effect of repeated freeze-thaw cycles of beef on the sensory, physicochemical quality and microbiological assessment. The effects of three successive freeze-thaw cycles on beef forelimb were investigated comparing with unfrozen fresh beef for 75 d by keeping at −20±1℃. The freeze-thaw cycles were subjected to three thawing methods and carried out to know the best one. As the number of freeze-thaw cycles increased color and odor declined significantly before cook within the cycles and tenderness, overall acceptability also declined among the cycles after cook by thawing methods. The thawing loss increased and dripping loss decreased significantly (pcycles and then decreased. Cooking loss increased in cycle 1 and 3, but decreased in cycle 2. pH decreased significantly (pcycles. Moreover, drip loss, cooking loss and WHC were affected (pcycles. 2-Thiobarbituric acid (TBARS) value increased (pcycles and among the cycles by thawing methods. Total viable bacteria, total coliform and total yeast-mould count decreased significantly (pcycles in comparison to the initial count in repeated freeze-thaw cycles. As a result, repeated freeze-thaw cycles affected the sensory, physicochemical and microbiological qua- lity of beef, causing the deterioration of beef quality, but improved the microbiological quality. Although repeated freeze-thaw cycles did not affect much on beef quality and safety but it may be concluded that repeated freeze and thaw should be minimized in terms of beef color for commercial value and WHC and tenderness/juiciness for eating quality. PMID:26761286

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

    OpenAIRE

    Shang, Huai-Shuai; Yi, Ting-Hua; Song, Yu-Pu

    2012-01-01

    An experimental study of plain concrete specimens of water-cement ratio 0.55, subjected to 0, 15, 25, 40, 50 and 75 cycles of freeze-thaw was completed. The dynamic modulus of elasticity (DME), weight loss, compressive strength, tensile strength, flexural strength, cleavage strength and stress-strain relationships of plain concrete specimens suffering from freeze-thaw cycles were measured. The experimental results showed that the strength decreased as the freeze-thaw cycles were repeated. A c...

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

    Science.gov (United States)

    Yoo, Seon-Mi; Han, Gui-Jung

    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. PMID:26761674

  10. Effec t of Freeze-Thaw Cycles on Lipid Oxidation and Myowater in Broiler Chickens

    Directory of Open Access Journals (Sweden)

    S Ali

    2016-03-01

    Full Text Available ABSTRACT The present study was carried out to investigate the influence of freezing-thawing cycles (0, 2, 4 and 6 on lipid oxidation and myowater contents and distribution. Nine replicates of chicken breast meat samples were used for each cycle. Lipid oxidation was determined by measuring peroxide value, and malondialdehyde (MDA concentrations, which reflect thiobarbituric acid reactive substance (TBARS. Color was determined with a digital colorimeter. Muscle moisture contents were determined by drip loss and thawing loss, water holding capacity, and nuclear magnetic resonance (NMR. The results showed that, as the number of freeze-thaw cycles increased, meat redness decreased and MDA and peroxide values increased. Drip loss and thawing loss tended to decreasing as the number of freeze-thaw cycles increased. Water holding capacity also decreased as a function of increasing freeze-thaw cycles. NMR relaxometry profile showed freeze-thaw cycles change the water distribution of meat subjected to multiple freeze-thaw cycles. In conclusion, multiple freezing and thawing rate (6 cycles increased lipid oxidation, decreased myowater, and impaired the color of chicken meat.

  11. 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.

  12. The thawing dark energy dynamics: Can we detect it?

    Energy Technology Data Exchange (ETDEWEB)

    Sen, S. [Centre for Theoretical Physics, Jamia Millia Islamia, New Delhi-110025 (India); Sen, A.A., E-mail: anjan.ctp@jmi.ac.i [Centre for Theoretical Physics, Jamia Millia Islamia, New Delhi-110025 (India); Sami, M. [Centre for Theoretical Physics, Jamia Millia Islamia, New Delhi-110025 (India)

    2010-03-15

    We consider different classes of scalar field models including quintessence and tachyon scalar fields with a variety of generic potentials belonging to the thawing type. We focus on observational quantities like Hubble parameter, luminosity distance as well as quantities related to the Baryon Acoustic Oscillation measurement. Our study shows that with present state of observations, one cannot distinguish amongst various models which in turn cannot be distinguished from cosmological constant. Our analysis indicates that there is a small chance to observe the dark energy metamorphosis in near future.

  13. 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

  14. Oxygenated thawing and rewarming alleviate rewarming injury of cryopreserved pancreatic islets.

    Science.gov (United States)

    Komatsu, Hirotake; Barriga, Alyssa; Medrano, Leonard; Omori, Keiko; Kandeel, Fouad; Mullen, Yoko

    2017-05-06

    Pancreatic islet transplantation is an effective treatment for Type 1 diabetic patients to eliminate insulin injections; however, a shortage of donor organs hinders the widespread use. Although long-term islet storage, such as cryopreservation, is considered one of the key solutions, transplantation of cryopreserved islets is still not practical due to the extensive loss during the cryopreservation-rewarming process. We have previously reported that culturing islets in a hyperoxic environment is an effective treatment to prevent islet death from the hypoxic injury during culture. In this study, we explored the effectiveness of thawing and rewarming cryopreserved islets in a hyperoxic environment. Following cryopreservation of isolated human islets, the thawing solution and culture media were prepared with or without pre-equilibration to 50% oxygen. Thawing/rewarming and the pursuant two-day culture were performed with or without oxygenation. Short-term recovery rate, defined as the volume change during cryopreservation and thawing/rewarming, was assessed. Ischemia-associated and inflammation-associated gene expressions were examined using qPCR after the initial rewarming period. Long-term recovery rate, defined as the volume change during the two-day culture after the thawing/rewarming, was also examined. Islet metabolism and function were assessed by basal oxygen consumption rate and glucose stimulated insulin secretion after long-term recovery. Oxygenated thawing/rewarming did not alter the short-term recovery rate. Inflammation-associated gene expressions were elevated by the conventional thawing/rewarming method and suppressed by the oxygenated thawing/rewarming, whereas ischemia-associated gene expressions did not change between the thawing/rewarming methods. Long-term recovery rate experiments revealed that only the combination therapy of oxygenated thawing/rewarming and oxygenated culture alleviated islet volume loss. These islets showed higher metabolism

  15. Hydraulic conductivity of compacted clay frozen and thawed in situ

    International Nuclear Information System (INIS)

    Benson, C.H.; Othman, M.A.

    1993-01-01

    A large specimen of compacted clay (diameter = 298 mm; thickness = 914 mm) was subjected to freeze-thaw in the field for 60 days. Afterward, the hydraulic conductivity was measured. The hydraulic conductivity of the entire specimen remained essentially unchanged, but increases in hydraulic conductivity of 1.5-2 orders of magnitude were observed above the freezing plane. The increase in hydraulic conductivity was highest at the top of the specimen and decreased with depth. Changes in hydraulic conductivity also occurred at depths 150 mm below the freezing plane, where desiccation occurred because of water redistribution. Numerous horizontal and vertical cracks formed in the soil mass. Dissection of the sample after permeation revealed that the cracks were laden with water. Cracking was greatest at the surface and became less frequent with depth. For depths greater than 150 mm below the freezing plane, cracking was absent. The frequency of cracks is consistent with principles of mechanistic models of soil freezing. The results of laboratory tests were used to predict the hydraulic conductivity of the large specimen. Tests were conducted on specimens subjected to various freeze-thaw cycles, temperature gradients, and states of stress. It was found that the predicted hydraulic conductivities were lower than those measured on the large specimen, but they closely resembled the trend in hydraulic conductivity with depth

  16. Atmospheric conditions of intense thaws in the Polish lowlands

    Energy Technology Data Exchange (ETDEWEB)

    Bednorz, Ewa [Adam Mickiewicz Univ., Poznan (Poland). Dept. of Climatology

    2012-02-15

    Synoptic conditions of daily changes in the snow cover depth by {>=} 5 cm were analyzed. Negative pressure anomalies appear over the North Atlantic and Scandinavia, which means low pressure systems moving over Europe along a northerly path. At the same time, positive pressure anomalies appear over the Mediterranean, indicating the expansion of the Azorean High. Such distribution of anomalies increases the horizontal baric gradient, which results in the intensification of the western and south western flow and stronger than usual winds from the SW quadrant. Transport of warm and humid air masses from the south-west brings about thaw-conducive conditions in central Europe: an increase in temperature and a considerable increase in the content of precipitable water, which means abundant precipitation. Different circulation types favorable for intense thawing were distinguished using the method of the hierarchical grouping. Two of them are characterized by the presence of deep and widespread cyclonal systems located north, north-west or west of the researched area. Less frequently, the decrease in the depth of snow cover occurs in the presence of the high located west over the Atlantic Ocean, which brings air masses from the north western direction. Such situations occur most frequently towards the end of winter. (orig.)

  17. Separation of Contaminants in The Freeze/Thaw Process

    Directory of Open Access Journals (Sweden)

    Szpaczyński Janusz A.

    2017-06-01

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

  18. 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

  19. Quality changes and freezing time prediction during freezing and thawing of ginger

    OpenAIRE

    Singha, Poonam; Muthukumarappan, Kasiviswanathan

    2015-01-01

    Abstract Effects of different freezing rates and four different thawing methods on chemical composition, microstructure, and color of ginger were investigated. Computer simulation for predicting the freezing time of cylindrical ginger for two different freezing methods (slow and fast) was done using ANSYS ? Multiphysics. Different freezing rates (slow and fast) and thawing methods significantly (P?

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

    NARCIS (Netherlands)

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

    2017-01-01

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

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

    NARCIS (Netherlands)

    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.; Walter Anthony, K. M.; Wickland, K.P.

    2015-01-01

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

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

    NARCIS (Netherlands)

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

    2017-01-01

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

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

    NARCIS (Netherlands)

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

    2016-01-01

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

  4. L-Band Microwave Emission of Soil Freeze-Thaw Process in the Third Pole Environment

    NARCIS (Netherlands)

    Zheng, Donghai; van der Velde, R.; Su, Z.; Zeng, Y.

    2017-01-01

    Soil freeze-thaw transition monitoring is essential for quantifying climate change and hydrologic dynamics over cold regions, for instance, the Third Pole. We investigate the L-band (1.4 GHz) microwave emission characteristics of soil freeze-thaw cycle via analysis of tower-based brightness

  5. 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...

  6. Assessment of the interaction between straw size and thawing rate and its impact on in vitro quality of post-thaw goat semen

    Directory of Open Access Journals (Sweden)

    Francisco Silvestre Brilhante Bezerra

    2012-03-01

    Full Text Available The objective of this study was to analyze interactions between different straw sizes and thawing rates on the post-thaw goat semen parameters. Twenty-one ejaculates (seven per animal were collected from three stud bucks by using an artificial vagina. After evaluation, the semen was extended in Tris-egg yolk-glycerol and packed in 0.25 and 0.50 mL straws, followed by storage in liquid nitrogen. Thawing was performed using two different rates: 37 ºC/1 min and 55 ºC/7 s. The interaction between the 0.5-mL straw and the thawing rate of 55 ºC/7 s promoted higher progressive motility. When the effect of straws alone was analyzed, it was verified that the use of the 0.50 mL straw promoted better conservation than the 0.25 mL one for progressive motility and acrosomal integrity, after the frozen-thawing procedures. Optimal results for progressive motility were achieved when goat semen was frozen in 0.5 mL straws and thawed in water at 55 ºC/7 s.

  7. The effect of extender, method of thawing, and duration of storage on in vitro fertility measures of frozen-thawed boar sperm.

    Science.gov (United States)

    Knox, R V; Ringwelski, J M; McNamara, K A; Aardsma, M; Bojko, M

    2015-08-01

    Frozen-thawed boar sperm (FTS) has reduced in vitro and in vivo life span compared to liquid semen. Experiments tested whether extenders, thawing procedures, and storage temperatures could extend the fertile life span of FTS. Experiment 1 tested the effect of six extenders on postthaw motility (MOT) and viability (VIA). Straws from boars (n = 6) were thawed, diluted into each extender, and evaluated at 20, 60, and 120 minutes. There was a trend (P = 0.08) for an extender-by-time interaction for MOT and effect of extender and time for MOT (P extender (P = 0.10) and time (P boar ejaculates (n = 15) were thawed at 50 °C for 10, 20, or 30 seconds or at 70 °C for 5, 10, or 20 seconds and evaluated at 5, 30, and 60 minutes. There was an effect of thawing treatment on MOT, VIA, and ACR (viable sperm with intact acrosomes, P extenders, thawing, and storage. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. 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

  9. 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.

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

    Science.gov (United States)

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

    2017-08-01

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

  11. 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.

  12. 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...

  13. 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

    It is well-known that laboratory testing of pervious concrete's freeze-thaw performance is too harsh and does not agree well with field observations. The most commonly used laboratory freeze-thaw test method for pervious concrete is similar to that used for conventional concrete even though...... the void structure of the two materials is completely different. In the present study, a new freeze-thaw test method for pervious concrete is suggested and tested on one baseline mix, with three different contents of entrained air. The evaluation of freeze-thaw damage on pervious concrete beams...... 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...

  14. Greenhouse Gas Exchange in Small Arctic Thaw Ponds

    Science.gov (United States)

    Laurion, I.; Bégin, P. N.; Bouchard, F.; Preskienis, V.

    2014-12-01

    Arctic lakes and ponds can represent up to one quarter of the land surface in permafrost landscapes, particularly in lowland tundra landscapes characterized by ice wedge organic polygons. Thaw ponds can be defined as the aquatic ecosystems associated to thawing of organic soils, either resulting from active layer processes and located above low-center peat polygons (hereafter low-center polygonal or LCP ponds), or resulting from thermokarst slumping above melting ice wedges linked to the accelerated degradation of permafrost (hereafter ice-wedge trough or IWT ponds). These ponds can merge together forming larger water bodies, but with relatively stable shores (hereafter merged polygonal or MPG ponds), and with limnological characteristics similar to LCP ponds. These aquatic systems are very small and shallow, and present a different physical structure than the larger thermokarst lakes, generated after years of development and land subsidence. In a glacier valley on Bylot Island, Nunavut, Canada, thermokarst and kettle lakes together represent 29% of the aquatic area, with a thermal profile resembling those of more standard arctic lakes (mixed epilimnion). The IWT ponds (44% of the area) are stratified for a large fraction of the summer despite their shallowness, while LCP and MPG ponds (27% of the area) show a more homogeneous water column. This will affect gas exchange in these diverse aquatic systems, in addition to their unique microbiota and organic carbon lability that control the production and consumption rates of greenhouse gases. The stratification in IWT ponds generates hypoxic conditions at the bottom, and together with the larger availability of organic carbon, stimulates methanogenesis and limits the mitigating action of methanotrophs. Overall, thaw ponds are largely supersaturated in methane, with IWT ponds dominating the emissions in this landscape (92% of total aquatic emissions estimated for the same valley), and they present large variations in

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

    Science.gov (United States)

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

    2012-01-01

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

  16. 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.

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

    NARCIS (Netherlands)

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

    2017-01-01

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

  18. Characterization and Modeling Of Microbial Carbon Metabolism In Thawing Permafrost

    Science.gov (United States)

    Graham, D. E.; Phelps, T. J.; Xu, X.; Carroll, S.; Jagadamma, S.; Shakya, M.; Thornton, P. E.; Elias, D. A.

    2012-12-01

    Increased annual temperatures in the Arctic are warming the surface and subsurface, resulting in thawing permafrost. Thawing exposes large pools of buried organic carbon to microbial degradation, increasing greenhouse gas generation and emission. Most global-scale land-surface models lack depth-dependent representations of carbon conversion and GHG transport; therefore they do not adequately describe permafrost thawing or microbial mineralization processes. The current work was performed to determine how permafrost thawing at moderately elevated temperatures and anoxic conditions would affect CO2 and CH4 generation, while parameterizing depth-dependent GHG production processes with respect to temperature and pH in biogeochemical models. These enhancements will improve the accuracy of GHG emission predictions and identify key biochemical and geochemical processes for further refinement. Three core samples were obtained from discontinuous permafrost terrain in Fairbanks, AK with a mean annual temperature of -3.3 °C. Each core was sectioned into surface/near surface (0-0.8 m), active layer (0.8-1.6 m), and permafrost (1.6-2.2 m) horizons, which were homogenized for physico-chemical characterization and microcosm construction. Surface samples had low pH values (6.0), low water content (18% by weight), low organic carbon (0.8%), and high C:N ratio (43). Active layer samples had higher pH values (6.4), higher water content (34%), more organic carbon (1.4%) and a lower C:N ratio (24). Permafrost samples had the highest pH (6.5), highest water content (46%), high organic carbon (2.5%) and the lowest C:N ratio (19). Most organic carbon was quantified as labile or intermediate pool versus stable pool in each sample, and all samples had low amounts of carbonate. Surface layer microcosms, containing 20 g sediment in septum-sealed vials, were incubated under oxic conditions, while similar active and permafrost layer samples were anoxic. These microcosms were incubated at -2

  19. 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.

  20. 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.

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

    Science.gov (United States)

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

    2017-11-22

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

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

    Directory of Open Access Journals (Sweden)

    Robert Novotny

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

  3. Methane bubbling from Siberian thaw lakes as a positive feedback to climate warming.

    Science.gov (United States)

    Walter, K M; Zimov, S A; Chanton, J P; Verbyla, D; Chapin, F S

    2006-09-07

    Large uncertainties in the budget of atmospheric methane, an important greenhouse gas, limit the accuracy of climate change projections. Thaw lakes in North Siberia are known to emit methane, but the magnitude of these emissions remains uncertain because most methane is released through ebullition (bubbling), which is spatially and temporally variable. Here we report a new method of measuring ebullition and use it to quantify methane emissions from two thaw lakes in North Siberia. We show that ebullition accounts for 95 per cent of methane emissions from these lakes, and that methane flux from thaw lakes in our study region may be five times higher than previously estimated. Extrapolation of these fluxes indicates that thaw lakes in North Siberia emit 3.8 teragrams of methane per year, which increases present estimates of methane emissions from northern wetlands (< 6-40 teragrams per year; refs 1, 2, 4-6) by between 10 and 63 per cent. We find that thawing permafrost along lake margins accounts for most of the methane released from the lakes, and estimate that an expansion of thaw lakes between 1974 and 2000, which was concurrent with regional warming, increased methane emissions in our study region by 58 per cent. Furthermore, the Pleistocene age (35,260-42,900 years) of methane emitted from hotspots along thawing lake margins indicates that this positive feedback to climate warming has led to the release of old carbon stocks previously stored in permafrost.

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

    Directory of Open Access Journals (Sweden)

    Fatemeh Ghasemian

    2012-01-01

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

  5. Resistance of human spermatozoa to cryoinjury in repeated cycles of thaw-refreezing

    Directory of Open Access Journals (Sweden)

    Sidney Verza Jr.

    2009-10-01

    Full Text Available Objective: To study the resistance of human spermatozoa to cryoinjury in repeated cycles of thaw-refreezing by using the fast liquid nitrogen vapor method. Material and Methods: Semen specimens were obtained from sixteen normal and oligozoospermic individuals who required disposal at the sperm bank. Five of them had testicular cancer. Specimens were thawed and an aliquot was removed for analysis. The remaining specimens were refrozen without removing the cryomedia. Repeated freeze-thaw cycles were performed until no motile sperm were observed. Sperm motility, number of motile spermatozoa and viability were determined after thawing. Resistance to cryoinjury was compared between groups and also after each refreezing cycle within groups. Results: Motile spermatozoa were recovered after five and two refreeze-thawing cycles in normozoospermic and oligozoospermic specimens, respectively. There were no significant differences in the recovery of motile spermatozoa between thaws within each group of normal and oligozoospermic specimens, but percentage motility and total number of motile spermatozoa were significantly lower in the oligozoospermic one. Specimens from men with cancer were exposed to six refreeze-thawing cycles. Although recovery of motile spermatozoa was significantly impaired after each thawing, there were no significant differences in the recovery of motile sperm between thaws in cancer and non-cancer groups. Conclusions: Human spermatozoa resist repeated cryopreservation using the fast liquid nitrogen vapor method. Normozoospermic specimens withstand refreezing for an average two cycles longer than oligozoospermic ones. Specimens from cancer patients seem to resist repeated cryoinjury similarly to non-cancer counterparts. Resistance to repeated cryoinjury was related to the initial semen quality.

  6. 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

  7. 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 .... moisture and the soil water evaporation process. The Songnen Plain ...... soils on soil infiltration and evaporation: Water Sci. Technol.

  8. 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...

  9. 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...

  10. 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.

  11. 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...

  12. Effect of moisture and freeze-thaw on mechanical properties of CRM asphalt mixture

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Nak-Seok; Cho, Kee-Ju [Kyonggi University, Suwon(Korea)

    2000-06-30

    This paper presents the experimental test results on moisture and freeze-thaw resistance of hot mix crumb rubber modified (CRM) asphalt concrete mixture. To compare the differences in mechanical properties of conventional and CRM asphalt concretes, various tests were conducted under different moisture conditions and freeze-thaw cycles. Marshall mix design was also performed to determine the optimum asphalt contents for the both asphalt concrete mixtures. Test results revealed that the moisture and freeze-thaw resistance of CRM asphalt mixture was superior to the conventional asphalt concrete. As a result, it is considered that the utilization of waste tires in asphalt pavements has the potential of minimizing the damage due to the moisture and freeze-thaw. (author). 9 refs., 4 tabs., 8 figs.

  13. Differentiation of fresh and frozen-thawed fish samples using Raman spectroscopy coupled with chemometric analysis.

    Science.gov (United States)

    Velioğlu, Hasan Murat; Temiz, Havva Tümay; Boyaci, Ismail Hakki

    2015-04-01

    The potential of Raman spectroscopy was investigated in terms of its capability to discriminate the species of the fish samples and determine their freshness according to the number of freezing/thawing cycles they exposed. Species discrimination analysis was carried out on sixty-four fish samples from six different species, namely horse mackerel (Trachurus trachurus), European anchovy (Engraulis encrasicolus), red mullet (Mullus surmuletus), Bluefish (Pomatamus saltatrix), Atlantic salmon (Salmo salar) and flying gurnard (Trigla lucerna). Afterwards, fish samples were exposed to different numbers of freezing/thawing cycles and separated into three batches, namely (i) fresh, (ii) once frozen-thawed (OF) and (iii) twice frozen-thawed (TF) samples, in order to perform the freshness analysis. Raman data collected were used as inputs for chemometric analysis, which enabled us to develop two main PCA models to successfully terminate the studies for both species discrimination and freshness determination analysis. Copyright © 2014 Elsevier Ltd. All rights reserved.

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

    DEFF Research Database (Denmark)

    Christensen, Søren; Tiedje, James M.

    1990-01-01

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

  15. 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.

  16. 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.

  17. Large scale CMB anomalies from thawing cosmic strings

    Energy Technology Data Exchange (ETDEWEB)

    Ringeval, Christophe [Centre for Cosmology, Particle Physics and Phenomenology, Institute of Mathematics and Physics, Louvain University, 2 Chemin du Cyclotron, 1348 Louvain-la-Neuve (Belgium); Yamauchi, Daisuke; Yokoyama, Jun' ichi [Research Center for the Early Universe (RESCEU), Graduate School of Science, The University of Tokyo, Tokyo 113-0033 (Japan); Bouchet, François R., E-mail: christophe.ringeval@uclouvain.be, E-mail: yamauchi@resceu.s.u-tokyo.ac.jp, E-mail: yokoyama@resceu.s.u-tokyo.ac.jp, E-mail: bouchet@iap.fr [Institut d' Astrophysique de Paris, UMR 7095-CNRS, Université Pierre et Marie Curie, 98bis boulevard Arago, 75014 Paris (France)

    2016-02-01

    Cosmic strings formed during inflation are expected to be either diluted over super-Hubble distances, i.e., invisible today, or to have crossed our past light cone very recently. We discuss the latter situation in which a few strings imprint their signature in the Cosmic Microwave Background (CMB) Anisotropies after recombination. Being almost frozen in the Hubble flow, these strings are quasi static and evade almost all of the previously derived constraints on their tension while being able to source large scale anisotropies in the CMB sky. Using a local variance estimator on thousand of numerically simulated Nambu-Goto all sky maps, we compute the expected signal and show that it can mimic a dipole modulation at large angular scales while being negligible at small angles. Interestingly, such a scenario generically produces one cold spot from the thawing of a cosmic string loop. Mixed with anisotropies of inflationary origin, we find that a few strings of tension GU = O(1) × 10{sup −6} match the amplitude of the dipole modulation reported in the Planck satellite measurements and could be at the origin of other large scale anomalies.

  18. 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.

  19. Effect of freeze-thaw repetitions upon the supercooling release ability of ice-nucleating bacteria

    International Nuclear Information System (INIS)

    Tsuchiya, Yooko; Hasegawa, Hiromi; Sasaki, Kazuhiro

    2004-01-01

    We have studied the durability of ice-nucleating bacteria with a potent supercooling release capacity through repeated freeze-thaw cycles. Through experiment, we confirmed that UV sterilized Erwinia ananas maintains a superior supercooling release capacity at around -1degC through 2000 freeze-thaw cycles. We also found that γ-ray sterilization, which is more suitable than UV for large-scale sterilization treatment, has a similar effect at appropriately selected doses. (author)

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

    Science.gov (United States)

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

    2016-05-01

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

  1. 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. PMID:25852660

  2. Thawing of ice in porous space of building materials: Experimental monitoring and computational modelling

    Science.gov (United States)

    Kočí, Jan; Maděra, Jiří; Kočí, Václav; Hlaváčová, Zuzana; Černý, Robert

    2017-11-01

    A simple laboratory experiment for the determination of thermal response of a studied sample during thawing is described in the paper. The sample made of autoclaved aerated concrete was partially water saturated and frozen. Then, the temperature development during thawing was recorded, allowing to identify the time scale of the phase change process taking place inside the sample. The experimental data was then used in the inverse analysis, in order to find unknown parameters of the smoothed effective specific heat capacity model.

  3. Post-thaw sperm characteristics following long-term storage of boar semen in liquid nitrogen.

    Science.gov (United States)

    Fraser, L; Strzeżek, J; Kordan, W

    2014-06-30

    This study investigated the effect of long-term liquid nitrogen storage of semen from individual boars on post-thaw sperm characteristics. Ejaculates, collected from five Polish large white (PLW) and five Polish landrace (PLR) boars, were frozen using a standard cryopreservation protocol. Post-thaw analysis was performed within a week (Period 1) and 42-48 months (Period 2) of semen storage in liquid nitrogen. Post-thaw sperm assessments included total motility, mitochondrial function (JC-1/PI assay), plasma membrane integrity (SYBR-14/PI assay), osmotic resistance test (ORT), lipid peroxidation (LPO) status and DNA fragmentation, analysed by the neutral Comet assay. Individual boar variability within breed and cryostorage periods had significant effects on the analysed parameters of frozen-thawed spermatozoa. Prolonged semen storage in liquid nitrogen (Period 2) induced a marked reduction in post-thaw sperm motility, mitochondrial function and plasma membrane integrity in most of the boars. Post-thaw semen of eight boars exhibited a marked decrease in osmotic resistance of the sperm acrosomal membrane, whereas a significant increase in the sperm cryo-susceptibility to induced LPO and DNA fragmentation was observed only in three boars after long-term semen storage. Additionally, frozen-thawed spermatozoa of PLR boars exhibited significantly lower osmotic resistance of the acrosomal membrane than PLW boars following prolonged semen storage in liquid nitrogen. The results of this study provide evidence of ageing processes in frozen-thawed boar spermatozoa following prolonged cryostorage. It seems that, even though cryopreservation allows long-term semen storage in liquid nitrogen, spermatozoa from individual boars are more susceptible to cryo-induced damage. Copyright © 2014 Elsevier B.V. All rights reserved.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-12-15

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

  5. Effect of multiple cycles of freeze-thawing on the RNA quality of lung cancer tissues.

    Science.gov (United States)

    Yu, Keke; Xing, Jie; Zhang, Jie; Zhao, Ruiying; Zhang, Ye; Zhao, Lanxiang

    2017-09-01

    RNA degradation is a major problem in tissue banking. We explored the effect of thawing flash-frozen biospecimens on the quality and integrity of RNA for genetic testing as well as for other cancer research studies. The histological quality of the frozen tumor sections was evaluated by using hematoxylin and eosin staining. RNA extraction from 60 lung cancer tissue samples subjected to various freeze/thaw cycles was performed using the RNeasy Plus isolation kit. RNA integrity was assessed by using an Agilent bioanalyzer to obtain RNA integrity numbers (RIN). Furthermore, RNA from different groups was used for fluorescence Reverse transcription-polymerase chain reaction (RT-PCR) analysis of the echinoderm microtubule-associated protein-like 4 and anaplastic lymphoma kinase (EML4-ALK) fusion gene mutation to verify whether it can be used for research or clinical testing. Highly variable RIN values were observed among the samples, which showed no correlation with the number of freeze/thaw cycles conducted. However, after 3 freeze/thaw cycles (each thaw event lasted for 10 min), an increasing number of changes in peak intensity in RINs were observed. After 5 freeze/thaw cycles, RNA integrity decreased to approximately 35%. After 3 freeze/thaw cycles, the RNA could still be used for RT-PCR analysis of EML4-ALK fusion gene mutations; whereas those subjected to 5 freeze/thaw cycles could not. Limited (cycles did not adversely affect the quality of RNA extracted from tumor tissues and subsequent RT-PCR analysis. Our data could be utilized in the establishment of a standardized procedure for tissue biospecimen collection and storage.

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

    International Nuclear Information System (INIS)

    Hafsteinsdottir, Erla G.; White, Duanne A.; Gore, Damian B.; Stark, Scott C.

    2011-01-01

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

  7. Physical and mathematical modeling of process of frozen ground thawing under hot tank

    Science.gov (United States)

    Zemenkova, M. Y.; Shastunova, U.; Shabarov, A.; Kislitsyn, A.; Shuvaev, A.

    2018-05-01

    A description of a new non-stationary thermophysical model in the “hot tank-frozen ground” system is given, taking into account mass transfer of pore moisture. The results of calculated and experimental data are presented, and the position of the thawing front is shown to be in good agreement with the convective heat transfer due to moisture migration in the thawed ground.

  8. Sperm DNA damage in relation to lipid peroxidation following freezing-thawing of boar semen

    OpenAIRE

    Fraser, L.; Strzeżek, J.; Wasilewska, K.; Pareek, C.S.

    2017-01-01

    This study investigated the relationships between lipid peroxidation (LPO) and sperm DNA damage following freezing-thawing of boar semen in different extenders. The comet assay was used to measure the extent of sperm DNA damage in a cryoprotectant-free extender or in cryoprotectant-based extenders after single and repeated freezing and thawing. As well as an analysis of sperm motion characteristics, mitochondrial function, membrane integrity, and lipid peroxidation (LPO) were assessed simulta...

  9. 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.

  10. Estimation of permafrost thawing rates in a sub-arctic catchment using recession flow analysis

    Directory of Open Access Journals (Sweden)

    S. W. Lyon

    2009-05-01

    Full Text Available Permafrost thawing is likely to change the flow pathways taken by water as it moves through arctic and sub-arctic landscapes. The location and distribution of these pathways directly influence the carbon and other biogeochemical cycling in northern latitude catchments. While permafrost thawing due to climate change has been observed in the arctic and sub-arctic, direct observations of permafrost depth are difficult to perform at scales larger than a local scale. Using recession flow analysis, it may be possible to detect and estimate the rate of permafrost thawing based on a long-term streamflow record. We demonstrate the application of this approach to the sub-arctic Abiskojokken catchment in northern Sweden. Based on recession flow analysis, we estimate that permafrost in this catchment may be thawing at an average rate of about 0.9 cm/yr during the past 90 years. This estimated thawing rate is consistent with direct observations of permafrost thawing rates, ranging from 0.7 to 1.3 cm/yr over the past 30 years in the region.

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

    Science.gov (United States)

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

    2017-04-01

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

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

    DEFF Research Database (Denmark)

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

    1998-01-01

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

  13. Large methane emission upon spring thaw from natural wetlands in the northern permafrost region

    International Nuclear Information System (INIS)

    Song Changchun; Sun Xiaoxin; Sun Li; Miao Yuqing; Wang Xianwei; Guo Yuedong; Xu Xiaofeng; Tian Hanqin

    2012-01-01

    The permafrost carbon–climate feedback is one of the major mechanisms in controlling the climate–ecosystem interactions in northern high latitudes. Of this feedback, methane (CH 4 ) emission from natural wetlands is critically important due to its high warming potential. The freeze–thaw transition has been confirmed to play an important role in annual CH 4 budget, yet the magnitude of this effect is uncertain. An intensive field campaign was carried out in the Sanjiang Plain, Northeast China to estimate the CH 4 emission in the spring freeze–thaw transition period. The observation concluded that a large CH 4 source was caused by spring thaw; the maximum hourly emission rate was 48.6 g C m −2 h −1 , more than three orders of the regularly observed CH 4 emission rate in the growing season. In some sporadically observed ‘hot spots’, the spring thawing effect contributed to a large CH 4 source of 31.3± 10.1 g C m −2 , which is approximately 80% of the previously calculated annual CH 4 emission in the same study area. If our results are typical for natural wetlands in the Northern Hemisphere permafrost region, we estimate a global CH 4 source strength of 0.5–1.0 Tg C (1 Tg =10 12 g) caused by spring thaw in the Northern Hemisphere permafrost region in the year 2011. Combining with available satellite and flask data, a regional extrapolation reaches a temporal pattern of CH 4 emission during 2003–2009 which is consistent with recently observed changes in atmospheric CH 4 concentration in the high latitudes. This suggests that the CH 4 emission upon spring thaw in the high latitudes might be enhanced by the projected climate warming. These findings indicate that the spring thawing effect is an important mechanism in the permafrost carbon–climate feedback and needs to be incorporated in Earth system models. (letter)

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

    Science.gov (United States)

    Kurylyk, Barret L.; 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.

  15. 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.

  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. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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

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

    Science.gov (United States)

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

    2013-12-01

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

  5. 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.

  6. 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.

  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. 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.

  9. 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

  10. 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.

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

    Directory of Open Access Journals (Sweden)

    Xingang Wang

    2014-01-01

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

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

    Science.gov (United States)

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

    2014-01-01

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

  13. 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.

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

    DEFF Research Database (Denmark)

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

    2013-01-01

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

  15. 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...

  16. 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...... temperatures can be calculated. The length change caused by temperature and ice content changes during test is measured by a separate experiment using the same types of freeze-thaw cycles as in the calorimetric tests. In this way it was possible to compare the amount of formed ice at different temperatures...... and the corresponding measured length changes. The development of cracks in the material structure was indicated by an ultra-sonic technique by measuring on the samples before and after the freeze-thaw tests. Further the air void structure was investigated using a microscopic technique in which air'bubble' size...

  17. 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

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

    Science.gov (United States)

    Ku, Jentung; Ottenstein, Laura; Krimchansky, Alexander

    2012-01-01

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

  19. Transfer of human frozen-thawed embryos with further cleavage during culture increases pregnancy rates

    Directory of Open Access Journals (Sweden)

    Bharat V Joshi

    2010-01-01

    Full Text Available Aim: To compare the pregnancy rate following transfer of frozen-thawed embryos with or without overnight culture after thawing. Settings and Design: This is a retrospective analysis of frozen-thawed embryo transfer (FET cycles performed between January 2006 and December 2008. Materials and Methods: Out of 518 thaw cycles, 504 resulted in embryo transfers (ETs. Of the total FET cycles, 415 were performed after an overnight culture of embryos (group A; and in 89 cycles, ET was performed within 2 hours of embryo thawing (group B. Statistical Analysis: The data were statistically analyzed using chi-square test. Results: We observed that with FET, women ≤30 years of age had a significantly higher (P=0.003 pregnancy rate (PR=28.9% as compared to women >30 years of age (17.5%. A significantly higher (P<0.001FNx08 pregnancy rate was also observed in women receiving 3 frozen-thawed embryos (29% as compared to those who received less than 3 embryos (10.7%. The difference in PR between group A (PR=24.3% and group B (PR=20.3% was not statistically significant. However, within group A, ET with cleaved embryos showed significantly ( P≤0.01 higher pregnancy rate compared to the uncleaved embryos, depending on the number of cleaved embryos transferred. Conclusion: No significant difference was noticed between FETs made with transfer of embryos with overnight culture and those without culture. However, within the cultured group, transfer of embryos cleaved during overnight culture gave significantly higher PR than transfers without any cleavage.

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

    Science.gov (United States)

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

    2017-09-01

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

  1. Effect of heterologous seminal plasma and semen extenders on motility of frozen-thawed ram spermatozoa

    Directory of Open Access Journals (Sweden)

    G.A. Mataveia

    2010-05-01

    Full Text Available Ram seminal plasma increases the fertility of frozen-thawed ram spermatozoa deposited into the cervix. The aim of the current study was to compare the effect of ram seminal plasma to that of bull seminal plasma, dog prostatic fluid, protein-free TALP, TrilEq (Triladyl with 0.5 mℓ of Equex STM paste added to each 100 mℓ and heat-treated skim milk on longevity and percentages of progressively motile and aberrantly motile frozen-thawed ram spermatozoa. Three ejaculates from each of 6 rams were extended in TrilEq, pooled and frozen in straws as a single batch per ram. One hundred and eight straws (3 straws from each ram for each fluid were thawed in random order. Once thawed, a straw was emptied into a tube with 0.85mℓ of the appropriate fluid at 37 °C and kept at that temperature for 6 h. Motility was assessed at x200 magnification immediately (time zero and 2, 4 and 6 h after thawing. Progressive motility decreased from each time to the next (P < 0.05 and was 39.0% (0 h, 26.0% (2 h, 19.6% (4 h and 12.6% (6 h; SEM 1.24, n=108 for each group. Ram seminal plasma resulted in higher progressive motility than bull seminal plasma, lower than milk, and similar to the other fluids. Ram seminal plasma resulted in lower aberrant motility than protein-free TALP and similar aberrant motility to other fluids. The effect of ram seminal plasma and dog prostatic fluid was very similar. The effect of ram seminal plasma on the fertility of frozen-thawed ram spermatozoa deposited into the cervix is not due an exceptionally beneficial effect on the motility of spermatozoa.

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

    Science.gov (United States)

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

    2015-12-01

    Permafrost peatlands in northern latitudes are large reservoirs of sequestered carbon that are vulnerable to climate change. While peatlands account for a small fraction of total global land surfaces, their potential to release sequestered carbon in response to higher temperatures is of concern. Of particular relevance is the conversion of these carbon stores into methane (CH4), a strong greenhouse gas with a global warming potential 20 times greater than that of CO2 over a 100-year time frame. Here, we explore how key nutrients impact the consumption of CH4 at the Stordalen Mire in Abisko, Sweden, a discontinuous permafrost peatland with expanding thaw over the last century. Peatland CH4 emissions are highly spatially variable due to multiple emission pathways and strong dependence on several environmental factors. Among controls on CH4 emissions, such as temperature and water table depth, primary production of wetland vegetation is also a strong factor in the variability of CH4 emissions. Plant community shifts among permafrost thaw stages subsequently change nutrient cycling and availability, which in turn impacts primary production. Early stages of permafrost thaw are mosaicked with a variety of vascular plants and mosses. We analyzed potential enzymatic activities of chitinase, glucosidase, and phosphatase as proxies for organic nitrogen, carbon, and phosphorus cycling, respectively, in tandem with potential CH4 oxidation rates. In addition, stoichiometric ratios of carbon, nitrogen, and phosphorus concentrations are used to illustrate nutrient limitation controls on CH4 oxidation rates. While CH4 emissions are low throughout initial thaw stages, highest rates of potential CH4 oxidation. These permafrost thaw-induced CH4 oxidation rates are 5 and 11 times higher, in the surface and depth of the peat profile respectively, than subsequent aerobic permafrost thaw stages. As CH4 emissions are low in intact permafrost peatlands, these high rates of potential CH4

  3. Comparison of enterotomy leak pressure among fresh, cooled, and frozen-thawed porcine jejunal segments.

    Science.gov (United States)

    Aeschlimann, Kimberly A; Mann, F A; Middleton, John R; Belter, Rebecca C

    2018-05-01

    OBJECTIVE To determine whether stored (cooled or frozen-thawed) jejunal segments can be used to obtain dependable leak pressure data after enterotomy closure. SAMPLE 36 jejunal segments from 3 juvenile pigs. PROCEDURES Jejunal segments were harvested from euthanized pigs and assigned to 1 of 3 treatment groups (n = 12 segments/group) as follows: fresh (used within 4 hours after collection), cooled (stored overnight at 5°C before use), and frozen-thawed (frozen at -12°C for 8 days and thawed at room temperature [23°C] for 1 hour before use). Jejunal segments were suspended and 2-cm enterotomy incisions were made on the antimesenteric border. Enterotomies were closed with a simple continuous suture pattern. Lactated Ringer solution was infused into each segment until failure at the suture line was detected. Leak pressure was measured by use of a digital transducer. RESULTS Mean ± SD leak pressure for fresh, cooled, and frozen-thawed segments was 68.3 ± 23.7 mm Hg, 55.3 ± 28.1 mm Hg, and 14.4 ± 14.8 mm Hg, respectively. Overall, there were no significant differences in mean leak pressure among pigs, but a significant difference in mean leak pressure was detected among treatment groups. Mean leak pressure was significantly lower for frozen-thawed segments than for fresh or cooled segments, but mean leak pressure did not differ significantly between fresh and cooled segments. CONCLUSIONS AND CLINICAL RELEVANCE Fresh porcine jejunal segments or segments cooled overnight may be used for determining intestinal leak pressure, but frozen-thawed segments should not be used.

  4. 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.

  5. 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.

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

    Science.gov (United States)

    2015-05-01

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

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

    Science.gov (United States)

    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 funct...

  8. A randomized controlled, non-inferiority trial of modified natural versus artificial cycle for cryo-thawed embryo transfer

    NARCIS (Netherlands)

    Groenewoud, E. R.; Cohlen, B. J.; Al-Oraiby, A.; Brinkhuis, E. A.; Broekmans, F. J. M.; de Bruin, J. P.; van den Dool, G.; Fleisher, K.; Friederich, J.; Goddijn, M.; Hoek, A.; Hoozemans, D. A.; Kaaijk, E. M.; Koks, C. A. M.; Laven, J. S. E.; van der Linden, P. J. Q.; Manger, A. P.; Slappendel, E.; Spinder, T.; Kollen, B. J.; Macklon, N. S.

    2016-01-01

    Are live birth rates (LBRs) after artificial cycle frozen-thawed embryo transfer (AC-FET) non-inferior to LBRs after modified natural cycle frozen-thawed embryo transfer (mNC-FET)? AC-FET is non-inferior to mNC-FET with regard to LBRs, clinical and ongoing pregnancy rates (OPRs) but AC-FET does

  9. A randomized controlled, non-inferiority trial of modified natural versus artificial cycle for cryo-thawed embryo transfer

    NARCIS (Netherlands)

    Groenewoud, E. R.; Cohlen, B. J.; Al-Oraiby, A.; Brinkhuis, E. A.; Broekmans, F. J. M.; de Bruin, J. P.; van den Dool, G.; Fleisher, K.; Friederich, J.; Goddijn, M.; Hoek, A.; Hoozemans, D. A.; Kaaijk, E. M.; Koks, C. A. M.; Laven, J. S. E.; van der Linden, P. J. Q.; Manger, A. P.; Slappendel, E.; Spinder, T.; Kollen, B. J.; Macklon, N. S.

    STUDY QUESTION: Are live birth rates (LBRs) after artificial cycle frozen-thawed embryo transfer (AC-FET) non-inferior to LBRs after modified natural cycle frozen-thawed embryo transfer (mNC-FET)? SUMMARY ANSWER: AC-FET is non-inferior to mNC-FET with regard to LBRs, clinical and ongoing pregnancy

  10. A randomized controlled, non-inferiority trial of modified natural versus artificial cycle for cryo-thawed embryo transfer

    NARCIS (Netherlands)

    Groenewoud, E. R.; Cohlen, B. J.; Al-Oraiby, A.; Brinkhuis, E. A.; Broekmans, F. J M; De Bruin, J. P.; Van Den Dool, G.; Fleisher, K.; Friederich, J.; Goddijn, M.; Hoek, A.; Hoozemans, D. A.; Kaaijk, E. M.; Koks, C. A M; Laven, J. S E; Van Der Linden, P. J Q; Manger, A. P.; Slappendel, E.; Spinder, T.; Kollen, B. J.; Macklon, N. S.

    2016-01-01

    studyquestion: Are live birth rates (LBRs) after artificial cycle frozen-thawed embryo transfer (AC-FET) non-inferior to LBRs after modified natural cycle frozen-thawed embryo transfer (mNC-FET)? summaryanswer: AC-FET is non-inferior to mNC-FET with regard to LBRs, clinical and ongoing pregnancy

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

    Science.gov (United States)

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

    2012-09-01

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

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

    NARCIS (Netherlands)

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

    2017-01-01

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

  13. Application of one-sided stress wave velocity measurement technique to evaluate freeze-thaw damage in concrete

    International Nuclear Information System (INIS)

    Lee, Joon Hyun; Park, Won Su

    1998-01-01

    It is well recognized that damage resulting from freeze-thaw cycles is a serious problems causing deterioration and degradation of concrete. In general, freeze-thaw cycles change the microstructure of the concrete ultimately leading to internal stresses and cracking. In this study, a new method for one-sided stress wave velocity measurement has been applied to evaluate freeze-thaw damage in concrete by monitoring the velocity change of longitudinal and surface waves. The freeze-thaw damage was induced in a 400 x 150 x 100 mm concrete specimen in accordance with ASTM C666 using s commercial testing apparatus. A cycle consisted of a variation of the temperature from -14 to 4 degrees Celsius. A cycle takes 4-5 hours with approximately equal times devoted to freezing-thawing. Measurement of longitudinal and surface wave velocities based on one-sided stress wave velocity measurement technique was made every 5 freeze-thaw cycle. The variation of longitudinal and surface wave velocities due to increasing freeze-thaw damage is demonstrated and compared to determine which one is more effective to monitor freeze-thaw cyclic damage progress. The variation in longitudinal wave velocity measured by one-sided technique is also compared with that measured by the conventional through transmission technique.

  14. 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...

  15. Perinatal outcomes of children born after frozen-thawed embryo transfer: a Nordic cohort study from the CoNARTaS group

    DEFF Research Database (Denmark)

    Wennerholm, UB; Henningsen, Anna-Karina Aaris; Romundstad, LB

    2013-01-01

    What are the risks of adverse outcomes in singletons born after frozen-thawed embryo transfer (FET)?......What are the risks of adverse outcomes in singletons born after frozen-thawed embryo transfer (FET)?...

  16. Permafrost thaw and wildfire: Equally important drivers of boreal tree cover changes in the Taiga Plains, Canada

    Science.gov (United States)

    Helbig, M.; Pappas, C.; Sonnentag, O.

    2016-02-01

    Boreal forests cover vast areas of the permafrost zones of North America, and changes in their composition and structure can lead to pronounced impacts on the regional and global climate. We partition the variation in regional boreal tree cover changes between 2000 and 2014 across the Taiga Plains, Canada, into its main causes: permafrost thaw, wildfire disturbance, and postfire regrowth. Moderate Resolution Imaging Spectroradiometer Percent Tree Cover (PTC) data are used in combination with maps of historic fires, and permafrost and drainage characteristics. We find that permafrost thaw is equally important as fire history to explain PTC changes. At the southern margin of the permafrost zone, PTC loss due to permafrost thaw outweighs PTC gain from postfire regrowth. These findings emphasize the importance of permafrost thaw in controlling regional boreal forest changes over the last decade, which may become more pronounced with rising air temperatures and accelerated permafrost thaw.

  17. The Impact of Repeated Freeze-Thaw Cycles on the Quality of Biomolecules in Four Different Tissues.

    Science.gov (United States)

    Ji, Xiaoli; Wang, Min; Li, Lingling; Chen, Fang; Zhang, Yanyang; Li, Qian; Zhou, Junmei

    2017-10-01

    High-quality biosamples are valuable resources for biomedical research. However, some tissues are stored without being sectioned into small aliquots and have to undergo repeated freeze-thaw cycles throughout prolonged experimentation. Little is known regarding the effects of repeated freeze-thaw cycles on the quality of biomolecules in tissues. The aim of this study was to evaluate the impact of repeated freeze-thaw (at room temperature or on ice) cycles on biomolecules and gene expression in four different types of tissues. Each fresh tissue was sectioned into seven aliquots and snap-frozen before undergoing repeated freeze-thaw cycles at room temperature or on ice. Biomolecules were extracted and analyzed. Both relative and absolute quantification were used to detect the changes in gene expression. The results indicated that the impact of repeated freeze-thaw cycles on RNA integrity varied by tissue type. Gene expression, including the housekeeping gene, was affected in RNA-degraded samples according to absolute quantification rather than relative quantification. Furthermore, our results suggest that thawing on ice could protect RNA integrity compared with thawing at room temperature. No obvious degradation of protein or DNA was observed with repeated freeze-thaw cycles either at room temperature or on ice. This research provides ample evidence for the necessity of sectioning fresh tissues into small aliquots before snap-freezing, thus avoiding degradation of RNA and alteration of gene expression resulting from repeated freeze-thaw cycles. For frozen tissue samples that were already in storage and had to be used repeatedly during their lifecycle, thawing on ice or sectioned at ultralow temperature is recommended.

  18. Deicer-freeze-thaw resistance characteristics of Portland cement concrete for Wisconsin pavements

    Science.gov (United States)

    1995-12-01

    The objectives of the study were to identify PCC mixes that offer increased deicer-freeze-thaw durability and to identify mix characteristics that contribute to premature durability distress. PCC mixes covering a range of air contents and water-cemen...

  19. Freeze-thaw resistance of concrete with marginal air content : final report

    Science.gov (United States)

    2006-12-01

    Freeze-thaw resistance is a key durability factor for concrete pavements. Recommendations for the air : void system parameters are normally: 6 1 percent total air, and spacing factor less than 0.20 : millimeters. However, it was observed that some...

  20. 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.

  1. 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…

  2. 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 ...

  3. A longer climate memory carried by soil freeze–thaw processes in Siberia

    International Nuclear Information System (INIS)

    Matsumura, Shinji; Yamazaki, Koji

    2012-01-01

    The climate memory of a land surface generally persists for only a few months, but analysis of surface meteorological data revealed a longer-term climate memory carried by soil freeze–thaw processes in Siberia. Surface temperature variability during the snowmelt season corresponds reasonably well with that in the summer of the following year, when most stations show a secondary autocorrelation peak. The surface temperature memory is thought to be stored as variations in the amount of snowmelt water held in the soil, and through soil freezing, which emerges as latent heat variations in the near-surface atmosphere during soil thawing approximately one year later. The ground conditions are dry in the longer-term climate memory regions, such as eastern Siberia, where less snow cover (higher surface air temperature) in spring results in less snowmelt water or lower soil moisture in the summer. Consequently, through soil freezing, it will require less latent heat to thaw in the summer of the following year, resulting in higher surface air temperature. In addition to soil moisture and snow cover, soil freeze–thaw processes can also act as agents of climate memory in the near-surface atmosphere. (letter)

  4. Theoretical study of heat transfer with moving phase-change interface in thawing of frozen food

    International Nuclear Information System (INIS)

    Leung, M; Ching, W H; Leung, D Y C; Lam, G C K

    2005-01-01

    A theoretical solution was obtained for a transient phase-change heat transfer problem in thawing of frozen food. In the physical model, a sphere originally at a uniform temperature below the phase-change temperature is suddenly immersed in a fluid at a temperature above the phase-change temperature. As the body temperature increases, the phase-change interface will be first formed on the surface. Subsequently, the interface will absorb the latent heat and move towards the centre until the whole body undergoes complete phase change. In the mathematical formulation, the nonhomogeneous problem arises from the moving phase-change interface. The solution in terms of the time-dependent temperature field was obtained by use of Green's function. A one-step Newton-Raphson method was specially designed to solve for the position of the moving interface to satisfy the interface condition. The theoretical results were compared with numerical results generated by a finite difference model and experimental measurements collected from a cold water thawing process. As a good agreement was found, the theoretical solution developed in this study was verified numerically and experimentally. Besides thawing of frozen food, there are many other practical applications of the theoretical solution, such as food freezing, soil freezing/thawing, metal casting and bath quenching heat treatment, among others

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

    Science.gov (United States)

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

    2017-12-01

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

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

    Directory of Open Access Journals (Sweden)

    P. De Palo

    2012-12-01

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

  7. Cryo-thawed embryo transfer : natural versus artificial cycle. A non-inferiority trial. (ANTARCTICA trial)

    NARCIS (Netherlands)

    Groenewoud, Eva R.; Macklon, Nick S.; Cohlen, Ben J.

    2012-01-01

    Background: Frozen thawed embryo transfer (FET) is a cost-effective adjunct to IVF or IVF-ICSI treatment. In order to optimize treatment outcome, FET should be carried out during a period of optimal endometrial receptivity. To optimize implantation several methods for endometrium preparation have

  8. 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 (effect of permafrost thaw on CH4 emissions from northern peatlands.

  9. 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.

  10. DSC and TMA studies on freezing and thawing gelation of galactomannan polysaccharide

    International Nuclear Information System (INIS)

    Iijima, Mika; Hatakeyama, Tatsuko; Hatakeyama, Hyoe

    2012-01-01

    Research highlights: ► Locust bean gum forms hydrogels by freezing and thawing. ► Syneresis was observed when freezing and thawing cycle (n) increased. ► Dynamic Young's modulus increased with increasing n. ► Non-freezing water content restrained by hydrogels decreased with increasing n. ► Strong gel with densely packed network structure formed with increasing n. - Abstract: Among various kinds of polysaccharides known to form hydrogels, locust bean gum (LBG) consisting of a mannose backbone and galactose side chains has unique characteristics, since LBG forms hydrogels by freezing and thawing. In this study, effect of thermal history on gelation was investigated by differential scanning calorimetry (DSC) and thermomechanical analysis (TMA). Gel/sol ratio calculated by weighing method was found to be affected by sol concentration, freezing rate and the number of freezing and thawing cycle (n). Once LBG hydrogels are formed, they are thermally stable, although syneresis was observed when n increased. Dynamic Young's modulus (E′) of hydrogels measured by TMA in water increased with increasing n and decreasing freezing rate. Non-freezing water calculated from DSC melting peak of ice in the gel decreased with increasing n and decreasing freezing rate. Morphological observation of freeze-dried gels was carried out by scanning electron microscopy (SEM). The above results indicate that weak hydrogel having large molecular network structure transformed into strong gel with densely packed network structure by increasing n and decreasing freezing rate.

  11. Theoretical study of heat transfer with moving phase-change interface in thawing of frozen food

    Science.gov (United States)

    Leung, M.; Ching, W. H.; Leung, D. Y. C.; Lam, G. C. K.

    2005-02-01

    A theoretical solution was obtained for a transient phase-change heat transfer problem in thawing of frozen food. In the physical model, a sphere originally at a uniform temperature below the phase-change temperature is suddenly immersed in a fluid at a temperature above the phase-change temperature. As the body temperature increases, the phase-change interface will be first formed on the surface. Subsequently, the interface will absorb the latent heat and move towards the centre until the whole body undergoes complete phase change. In the mathematical formulation, the nonhomogeneous problem arises from the moving phase-change interface. The solution in terms of the time-dependent temperature field was obtained by use of Green's function. A one-step Newton-Raphson method was specially designed to solve for the position of the moving interface to satisfy the interface condition. The theoretical results were compared with numerical results generated by a finite difference model and experimental measurements collected from a cold water thawing process. As a good agreement was found, the theoretical solution developed in this study was verified numerically and experimentally. Besides thawing of frozen food, there are many other practical applications of the theoretical solution, such as food freezing, soil freezing/thawing, metal casting and bath quenching heat treatment, among others.

  12. 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...

  13. 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...

  14. 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

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

    NARCIS (Netherlands)

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

    2017-01-01

    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

  16. Two successful pregnancies following autotransplantation of frozen/thawed ovarian tissue

    DEFF Research Database (Denmark)

    Andersen, Claus Yding; Rosendahl, M.; Byskov, A.G.

    2008-01-01

    of frozen/thawed ovarian tissue. METHODS: One complete ovary was cryopreserved from each of six patients who were 26-35 years old prior to treatment. Tissue from three of the patients was transported 4-5 h on ice prior to cryopreservation. After a period of 17-32 months, orthotopic autotransplantation...

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

    Lifescience Database Archive (English)

    Full Text Available ndard Gene Name in SGD Growth rate BM/BW Rate of growth in non-strees condition (Mutant/Wild-type) Growth ra...te (AM/AW)/(BM/BW) AM/AW represents rate of growth after exposure to freeze-thaw strees

  18. Effect of fast freeze-thaw cycles on mechanical properties of ordinary-air-entrained concrete.

    Science.gov (United States)

    Shang, Huai-shuai; Cao, Wei-qun; Wang, Bin

    2014-01-01

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

  19. 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...

  20. Primary production, nutrient dynamics and mineralisation in a northeastern Greenland fjord during the summer thaw

    DEFF Research Database (Denmark)

    Rysgaard, S.; Finster, K.; Dahlgaard, H.

    1996-01-01

    This investigation represents the first integrated study of primary production, nutrient dynamics and mineralisation in a northeastern fjord of Greenland. The data presented represent conditions and activities during the early summer thaw (first 2 weeks of July). Primary production (5.3 mmol C m(...

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

    Science.gov (United States)

    De Palo, P.; Maggiolino, A.; Centoducati, P.; Tateo, A.

    2012-01-01

    The aim of the present work was to investigate how colour changes of foal meat can vary after thawing out in relation to the slaughtering age of the horses and to the post-thawing time. Eighteen Italian Heavy Draught Horse (IHDH) foals were used for the trial. They were subdivided in three groups according to their slaughtering age (6, 11 and 18 months). Two different surfaces were investigated for each sample: a fresh cut surface (daily renewed cutting surface: DRCS), and not-renewed cutting surface (NRCS). The redness of both investigated surfaces increased with slaughtering age (p<0.01). Moreover, this parameter decreased during post-thawing time (p<0.01) only on the NRCS, probably due to the myoglobin oxidation processes. Colour is an important visual cue denoting perceived quality by consumers. So, by a chromatic perspective the thawed meat of IHDH foals slaughtered at 6 and 11 months proved to be that which best meets the market requirements. PMID:25049544

  2. Effects of reduced glutathione on acrosin activity in frozen-thawed boar spermatozoa.

    Science.gov (United States)

    Estrada, Efrén; Rodríguez-Gil, Joan E; Rivera Del Álamo, Maria M; Peña, Alejandro; Yeste, Marc

    2017-02-01

    In pigs, acrosin activity in extended semen is correlated with reproductive performance and has recently been identified as a freezability marker. Reduced glutathione (GSH) is known to decrease sperm cryodamage and increase the reproductive performance of frozen-thawed boar spermatozoa. However, the effects of GSH on the acrosin activity of good and poor freezability ejaculates (GFE and PFE, respectively) is yet to be examined. The present study investigated how supplementing cryopreservation media with GSH affected acrosin activity in GFE and PFE, as well as the relationship between acrosin activity and reproductive performance in frozen-thawed boar spermatozoa. In addition, we examined whether the increase in fertility rates and litter sizes observed after the addition of 2mM GSH to cryopreservation extenders was related to acrosin activity. Supplementing freezing media with 2mM GSH partially counteracted the cryopreservation-related decrease in acrosin activity in GFE but not PFE. Acrosin activity was found to be significantly correlated with in vivo reproductive performance of frozen-thawed boar semen. In conclusion, the effects of adding GSH to freezing extenders on the acrosin activity of frozen-thawed boar spermatozoa rely on the intrinsic freezability of the ejaculate. Furthermore, the maintenance of proper acrosin activity could contribute to the increase in reproductive performance mediated by GSH.

  3. 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

  4. 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.

  5. Directions, Objectives, and Author's Concepts of Audiovisual Media Interpretations of School and University Theme in the Soviet Cinema of the "Thaw" Period (1956-1968)

    Science.gov (United States)

    Fedorov, Alexander; Levitskaya, Anastasia; Gorbatkova, Olga; Mamadaliev, Anvar M.

    2017-01-01

    The "thaw period" films (1956-1968) on the school/university topic can be conditionally divided into two stages: early (1956-1963) and late "thaw" (1964-1968), although, naturally, there was a somewhat diffusion between these periods. The "thaw" audiovisual texts about school and university life, according to the…

  6. Effects of freezing-thawing on sensory descriptive profiles of cooked poultry breast meat

    Directory of Open Access Journals (Sweden)

    ZHUANG Hong

    2014-12-01

    Full Text Available Freezing is a common method used by consumers to extend meat shelf life and by researchers to allow for subsequent meat quality assessments and processing.However,the effects of freezing on the sensory quality of cooked poultry breast meat are not well documented.The objective of this study was to compare sensory quality profiles of fresh and frozen/thawed chicken breast fillets (pectoralis major.Breast fillets were removed from carcasses within 24 h postmortem and either cooked from a fresh state or placed in a -20℃ freezer.Frozen samples were thawed by three different methods:thawing during cooking directly from a frozen state (0 h,thawing in 20℃ water for 2 h prior to cooking (2 h,or thawing at 4℃ for 24 h prior to cooking (24 h.A control treatment with fillets cooked directly from a fresh state was used.Fillets were cooked to an endpoint temperature of 78℃ and sensory quality was evaluated by trained descriptive panelists using 0~15 universal intensity scales.Results show that there were not treatment differences (P>0.05 in the average intensity scores for any of the descriptive flavor attributes or for 5 of the descriptive texture attributes (cohesiveness,hardness,juiciness,wad size,and wetness of wad.However,the intensity scores for cohesiveness of mass,rate of breakdown,and chewiness were significantly different among the treatments (P<0.05.Cohesiveness of mass intensity scores for 0h and 24 h fillets were significantly higher than 2 h samples.Fillets cooked directly from a frozen state (0 h had significantly higher intensity scores for rate of breakdown and chewiness than fresh controls and 2 h samples,respectively.These results indicate that freezing-thawing does not affect sensory flavor quality;however,it may change the texture attributes of cooked chicken breast meat products.The effects on meat texture depend on thawing methods prior to cooking.

  7. 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

  8. Micromechanical properties of canine femoral articular cartilage following multiple freeze-thaw cycles.

    Science.gov (United States)

    Peters, Abby E; Comerford, Eithne J; Macaulay, Sophie; Bates, Karl T; Akhtar, Riaz

    2017-07-01

    Tissue material properties are crucial to understanding their mechanical function, both in healthy and diseased states. However, in certain circumstances logistical limitations can prevent testing on fresh samples necessitating one or more freeze-thaw cycles. To date, the nature and extent to which the material properties of articular cartilage are altered by repetitive freezing have not been explored. Therefore, the aim of this study is to quantify how articular cartilage mechanical properties, measured by nanoindentation, are affected by multiple freeze-thaw cycles. Canine cartilage plugs (n = 11) from medial and lateral femoral condyles were submerged in phosphate buffered saline, stored at 3-5°C and tested using nanoindentation within 12h. Samples were then frozen at -20°C and later thawed at 3-5°C for 3h before material properties were re-tested and samples re-frozen under the same conditions. This process was repeated for all 11 samples over three freeze-thaw cycles. Overall mean and standard deviation of shear storage modulus decreased from 1.76 ± 0.78 to 1.21 ± 0.77MPa (p = 0.91), shear loss modulus from 0.42 ± 0.19 to 0.39 ± 0.17MPa (p=0.70) and elastic modulus from 5.13 ± 2.28 to 3.52 ± 2.24MPa (p = 0.20) between fresh and three freeze-thaw cycles respectively. The loss factor increased from 0.31 ± 0.38 to 0.71 ± 1.40 (p = 0.18) between fresh and three freeze-thaw cycles. Inter-sample variability spanned as much as 10.47MPa across freezing cycles and this high-level of biological variability across samples likely explains why overall mean "whole-joint" trends do not reach statistical significance across the storage conditions tested. As a result multiple freeze-thaw cycles cannot be explicitly or statistically linked to mechanical changes within the cartilage. However, the changes in material properties observed herein may be sufficient in magnitude to impact on a variety of clinical and scientific studies of cartilage, and should be considered

  9. Spring photosynthetic onset and net CO2 uptake in Alaska triggered by landscape thawing.

    Science.gov (United States)

    Parazoo, Nicholas C; Arneth, Almut; Pugh, Thomas A M; Smith, Ben; Steiner, Nicholas; Luus, Kristina; Commane, Roisin; Benmergui, Josh; Stofferahn, Eric; Liu, Junjie; Rödenbeck, Christian; Kawa, Randy; Euskirchen, Eugenie; Zona, Donatella; Arndt, Kyle; Oechel, Walt; Miller, Charles

    2018-04-24

    The springtime transition to regional-scale onset of photosynthesis and net ecosystem carbon uptake in boreal and tundra ecosystems are linked to the soil freeze-thaw state. We present evidence from diagnostic and inversion models constrained by satellite fluorescence and airborne CO 2 from 2012 to 2014 indicating the timing and magnitude of spring carbon uptake in Alaska correlates with landscape thaw and ecoregion. Landscape thaw in boreal forests typically occurs in late April (DOY 111 ± 7) with a 29 ± 6 day lag until photosynthetic onset. North Slope tundra thaws 3 weeks later (DOY 133 ± 5) but experiences only a 20 ± 5 day lag until photosynthetic onset. These time lag differences reflect efficient cold season adaptation in tundra shrub and the longer dehardening period for boreal evergreens. Despite the short transition from thaw to photosynthetic onset in tundra, synchrony of tundra respiration with snow melt and landscape thaw delays the transition from net carbon loss (at photosynthetic onset) to net uptake by 13 ± 7 days, thus reducing the tundra net carbon uptake period. Two global CO 2 inversions using a CASA-GFED model prior estimate earlier northern high latitude net carbon uptake compared to our regional inversion, which we attribute to (i) early photosynthetic-onset model prior bias, (ii) inverse method (scaling factor + optimization window), and (iii) sparsity of available Alaskan CO 2 observations. Another global inversion with zero prior estimates the same timing for net carbon uptake as the regional model but smaller seasonal amplitude. The analysis of Alaskan eddy covariance observations confirms regional scale findings for tundra, but indicates that photosynthesis and net carbon uptake occur up to 1 month earlier in evergreens than captured by models or CO 2 inversions, with better correlation to above-freezing air temperature than date of primary thaw. Further collection and analysis of boreal evergreen species over

  10. 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

  11. The impacts of recent permafrost thaw on land–atmosphere greenhouse gas exchange

    International Nuclear Information System (INIS)

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

    2014-01-01

    Permafrost thaw and the subsequent mobilization of carbon (C) stored in previously frozen soil organic matter (SOM) have the potential to be a strong positive feedback to climate. As the northern permafrost region experiences as much as a doubling of the rate of warming as the rest of the Earth, the vast amount of C in permafrost soils is vulnerable to thaw, decomposition and release as atmospheric greenhouse gases. Diagnostic and predictive estimates of high-latitude terrestrial C fluxes vary widely among different models depending on how dynamics in permafrost, and the seasonally thawed ‘active layer’ above it, are represented. Here, we employ a process-based model simulation experiment to assess the net effect of active layer dynamics on this ‘permafrost carbon feedback’ in recent decades, from 1970 to 2006, over the circumpolar domain of continuous and discontinuous permafrost. Over this time period, the model estimates a mean increase of 6.8 cm in active layer thickness across the domain, which exposes a total of 11.6 Pg C of thawed SOM to decomposition. According to our simulation experiment, mobilization of this previously frozen C results in an estimated cumulative net source of 3.7 Pg C to the atmosphere since 1970 directly tied to active layer dynamics. Enhanced decomposition from the newly exposed SOM accounts for the release of both CO 2 (4.0 Pg C) and CH 4 (0.03 Pg C), but is partially compensated by CO 2 uptake (0.3 Pg C) associated with enhanced net primary production of vegetation. This estimated net C transfer to the atmosphere from permafrost thaw represents a significant factor in the overall ecosystem carbon budget of the Pan-Arctic, and a non-trivial additional contribution on top of the combined fossil fuel emissions from the eight Arctic nations over this time period. (paper)

  12. 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.

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

    Science.gov (United States)

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

    2014-01-01

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

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Shallow soil moisture – ground thaw interactions and controls – Part 1: Spatiotemporal patterns and correlations over a subarctic landscape

    Directory of Open Access Journals (Sweden)

    X. J. Guan

    2010-07-01

    Full Text Available Soil moisture and ground thaw state are both indicative of a hillslope's ability to transfer water. In cold regions, in particular, it is widely known that the depth of the active layer and wetness of surface soils are important for runoff generation, but the diversity of interactions between ground thaw and surface soil moisture themselves has not been studied. To fill this knowledge gap, detailed shallow soil moisture and thaw depth surveys were conducted along systematic grids at the Baker Creek Basin, Northwest Territories. Multiple hillslopes were studied to determine how the interactions differed along a spectrum of topological, typological and topographic situations across the landscape. Overall results did not show a simple link between soil moisture and ground thaw as was expected. Instead, correlation was a function of wetness. The interaction between soil moisture and ground thaw was more dependent at wetter sites. This indicates that interactive soil moisture and thaw depth behaviour on hillslopes in cold regions changes with location and cannot necessarily be lumped together in hydrological models. To explore further why these differences arise, a companion paper (Guan et al., 2010 will examine how the hydrological and energy fluxes influenced the patterns of moisture and thaw among the study sites.

  19. Climate Change and Thawing Permafrost in Two Iñupiaq Communities of Alaska's Arctic: Observations, Implications, and Resilience

    Science.gov (United States)

    Woodward, A.; Kofinas, G.

    2013-12-01

    For thousands of years the Iñupiat of northern Alaska have relied on ecosystems underlain by permafrost for material and cultural resources. As permafrost thaws across the Arctic, these social-ecological systems are changing rapidly. Community-based research and extensive local knowledge of Iñupiaq villagers offer unique and valuable contributions to understanding permafrost change and its implications for humans. We partnered with two Iñupiaq communities in Alaska's Arctic to investigate current and potential effects of thawing permafrost on social-ecological systems. Anaktuvuk Pass is situated on thaw-stable consolidated gravel in the Brooks Range, while Selawik rests on ice-rich permafrost in Beringia lowland tundra. Using the transdisciplinary approach of resilience theory and mixed geophysical and ethnographic methods, we measured active layer thaw depths and documented local knowledge about climate and permafrost change. Thaw depths were greater overall in Selawik. Residents of both communities reported a variety of changes in surface features, hydrology, weather, flora, and fauna that they attribute to thawing permafrost and / or climate change. Overall, Selawik residents described more numerous and extreme examples of such changes, expressed higher degrees of certainty that change is occurring, and anticipated more significant and negative implications for their way of life than did residents of Anaktuvuk Pass. Of the two villages, Selawik faces greater and more immediate challenges to the resilience of its social-ecological system as permafrost thaws.

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

    Science.gov (United States)

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

    2017-07-01

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

  1. 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.

  2. 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.

  3. Frozen-Thawed Embryo Transfer Cycles Have a Lower Incidence of Ectopic Pregnancy Compared With Fresh Embryo Transfer Cycles.

    Science.gov (United States)

    Zhang, Xinyu; Ma, Caihong; Wu, Zhangxin; Tao, Liyuan; Li, Rong; Liu, Ping; Qiao, Jie

    2017-01-01

    To evaluate the risk of ectopic pregnancy of embryo transfer. A retrospective cohort study on the incidence of ectopic pregnancy in fresh and frozen-thawed embryo transfer cycles from January 1 st , 2010, to January 1 st , 2015. Infertile women undergoing frozen-thawed transfer cycles or fresh transfer cycles. In-vitro fertilization, fresh embryo transfer, frozen-thawed embryo transfer, ectopic pregnancy. Ectopic pregnancy rate and clinical pregnancy rate. A total of 69 756 in vitro fertilization-embryo transfer cycles from 2010 to 2015 were analyzed, including 45 960 (65.9%) fresh and 23 796 (34.1%) frozen-thawed embryo transfer cycles. The clinical pregnancy rate per embryo transfer was slightly lower in fresh embryo transfer cycles compared with frozen-thawed embryo transfer cycles (40.8% vs 43.1%, P cycles, blastocyst transfer shows a significantly lower incidence of ectopic pregnancy (0.8% vs 1.8%, P = .002) in comparison with day 3 cleavage embryo transfer. The risk of ectopic pregnancy is lower in frozen-thawed embryo transfer cycles than fresh embryo transfer cycles, and blastocyst transfer could further decrease the ectopic pregnancy rate in frozen-thawed embryo transfer cycles.

  4. 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.

  5. 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

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

    DEFF Research Database (Denmark)

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

    2016-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Sally E Hall

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

  8. Monitoring Bare Soil Freeze–Thaw Process Using GPS-Interferometric Reflectometry: Simulation and Validation

    Directory of Open Access Journals (Sweden)

    Xuerui Wu

    2017-12-01

    Full Text Available Frozen soil and permafrost affect ecosystem diversity and productivity as well as global energy and water cycles. Although some space-based Radar techniques or ground-based sensors can monitor frozen soil and permafrost variations, there are some shortcomings and challenges. For the first time, we use GPS-Interferometric Reflectometry (GPS-IR to monitor and investigate the bare soil freeze–thaw process as a new remote sensing tool. The mixed-texture permittivity models are employed to calculate the frozen and thawed soil permittivities. When the soil freeze/thaw process occurs, there is an abrupt change in the soil permittivity, which will result in soil scattering variations. The corresponding theoretical simulation results from the forward GPS multipath simulator show variations of GPS multipath observables. As for the in-situ measurements, virtual bistatic radar is employed to simplify the analysis. Within the GPS-IR spatial resolution, one SNOTEL site (ID 958 and one corresponding PBO (plate boundary observatory GPS site (AB33 are used for analysis. In 2011, two representative days (frozen soil on Doy of Year (DOY 318 and thawed soil on DOY 322 show the SNR changes of phase and amplitude. The GPS site and the corresponding SNOTEL site in four different years are analyzed for comparisons. When the soil freeze/thaw process occurred and no confounding snow depth and soil moisture effects existed, it exhibited a good absolute correlation (|R| = 0.72 in 2009, |R| = 0.902 in 2012, |R| = 0.646 in 2013, and |R| = 0.7017 in 2014 with the average detrended SNR data. Our theoretical simulation and experimental results demonstrate that GPS-IR has potential for monitoring the bare soil temperature during the soil freeze–thaw process, while more test works should be done in the future. GNSS-R polarimetry is also discussed as an option for detection. More retrieval work about elevation and polarization combinations are the focus of future development.

  9. The impact of freeze-thawing on the friability of formed elemental sulfur

    Energy Technology Data Exchange (ETDEWEB)

    Clark, P.D.; Almond, P.

    1995-10-01

    Winter weather fluctuation tests were performed in a laboratory to determine the freeze-thaw effect on the particle size distribution and friability of sulfur samples of Polish Air Prills, Procor GX Granules, Petrosul, Sandvik Rotoform, and slate. Formed elemental sulfur is often stored outdoors and is subjected to temperature fluctuations which could potentially result in structural stress, particularly if the sulfur contained any moisture from rainwater or melting snow. Concern was expressed that sulfur stored under these conditions might have increased friability during shipping and handling. Results of stress level tests indicated that winter weather fluctuations did not effect the particle size distribution or friability of the samples. When sulfur samples were in contact with water for one month, there were was no significant change in overall friability. It was concluded that all premium product forms of solid elemental sulfur could be stored outdoors, even if subjected to freeze-thaw cycles. 4 tabs., 5 figs.

  10. Factors Analysis of Spontaneous Abortion after Thawed-vitrified Blastocysts Transfer

    Institute of Scientific and Technical Information of China (English)

    Dong YANG; Zheng-yi SUN; Cheng-yan DENG; Qi YU; Fang-fang HE

    2008-01-01

    Objective To investigate the factors resulting in spontaneous abortion after transferring frozen-thawing blastocysts. Methods A total of 108 cases transferring vitrified blastocysts were divided into two groups: abortion group (n =20) and ongoing group (n=88). Cytogenetic analysis of apoblemas was performed in 12 cases of the abortion.Results The overall spontaneous abortion rate was 18.50%(20/108) and the early spontaneous rate was 16.67%(18/108). ,4 significant difference in maternal age was observed (abortion group: 33.3±4.0 years, ongoing group: 31.0±3.6 years, P=0.02). No difference in other parameters was found. Cytogenetic analysis of apoblemas was obtained for 12 cases, and 2 specimens were contaminated. Seven of ten patients had abnormal karyotypes. Conclusion The underlying cause of spontaneous abortion after transferring frozen thawing blastocysts appears to be abnormal karyotypes.Advancing maternal age seems to increase the risk of spontaneous abortion.

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

  12. 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.

  13. 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...

  14. 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

    phase, and in a subsequent equilibration phase. A single deep freeze treatment phase enhanced dissolved total and labelled N pools in the soil solution at initial thaw, and resulted in reduced pool sizes at the end of the equilibration phase. By contrast, a multiple freeze-thaw cycling treatment......, these results indicate that moderate freeze-thaw fluctuations may have minimal influences on microbial biomass pools, but nevertheless can have strong contrasting effects on the amounts, forms, and timing of N and organic C supply into the soil solution. Ecosystem losses via N2O effluxes were of greatest...... directly enhanced the dissolved labelled N pool, but did not significantly affect dissolved total N. Furthermore, both dissolved labelled N and dissolved total N pools were significantly enhanced in the equilibration period following multiple freeze-thaw, the latter due to a marked increase in soil...

  15. 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...

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

    Science.gov (United States)

    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.

  17. Effects of different cryoprotectants and freezing methods on post-thaw boar semen quality.

    Science.gov (United States)

    Yang, Chung-Hsun; Wu, Ting-Wen; Cheng, Feng-Pang; Wang, Jiann-Hsiung; Wu, Jui-Te

    2016-03-01

    The current study aimed to investigate the effects of different concentrations of glycerol (0%, 1%, 2%, 3%, and 5%) and dimethylacetamide (DMA: 0%, 1%, 3%, and 5%) on post-sperm quality characteristics following semen freezing in dry ice (D) or liquid nitrogen (N). Semen was collected from Duroc boars and was allocated to 32 treatment groups for cryopreservation. Analysis of post-thaw semen quality and fertility after artificial insemination (AI) was used to examine the combinatorial effects of different treatments. The best scores for post-thaw sperm motility, sperm viability, and sperm acrosomal integrity were observed in semen frozen in: (a) dry ice in the presence of 5% glycerol and no DMA (16D-treatment); (b) dry ice in the presence of 3% glycerol and no DMA (9D-treatment); and (c) liquid nitrogen in the presence of 3% glycerol and 1% DMA (10N-treatment), with no significant difference observed among these three treatments. The farrowing rates after AI with post-thawed semen after 9D- and 10N-treatments were 33% and 50%, respectively. To summarize, the results of the present study indicated that the freezing extender containing 3% glycerol in combination with the straw-freezing method using dry ice produced the best post-thaw quality parameters of boar semen. Combinations of glycerol and DMA did not enhance the cryosurvival of boar spermatozoa. Copyright © 2016 Society for Biology of Reproduction & the Institute of Animal Reproduction and Food Research of Polish Academy of Sciences in Olsztyn. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

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

    Science.gov (United States)

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

    2014-01-01

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

  19. 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...

  20. Detection of freeze-thaw weathering effect using X-ray micro computed tomography

    Science.gov (United States)

    Park, J.; Hyun, C.; Park, H.

    2011-12-01

    Physical weathering caused by repeated freeze-thaw action of water inside rock pores or cracks was artificially simulated in laboratory. The tests were conducted on three rock types, i.e. diorite, basalt, and tuff, which are the major rock types around King Sejong Station of Korea located in Barton Peninsula, King George Island, Antarctica. The temperature of freeze-thaw cycle was also set with simulated the air temperature of the station, i.e. the maximum temperature was + 10 °C and the minimum temperature was - 20 °C. Three cylindrical specimens composed of one for each rock type with 24.6 mm diameter and 14.5 ~ 17.7 mm length were prepared, and 2 mm diameter and 7 mm shallow depth hole was drilled on the center of the specimens. To exaggerate the effect of the freeze-thaw weathering, all tests were conducted under completely saturated condition. 50 cycles of the freeze-thaw test was carried, and X-ray micro computed tomography (CT) images of each rock specimen were obtained after every 10 cycles. Using X-ray micro CT images, 3D structure was rendered and pore and crack structures were extracted. The changes of porosity, absorption rate and pore and crack structure were detected. Porosity of all specimens was decreased linearly and absorption rate of all specimens was increased linearly as weathering processes; the pore connection and crack propagation was detected in 3D rendering pore and crack structure. The change of tuff specimen is the most remarkable among three rock types used in the research, because of its relatively high initial absorption rate and low strength. This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MEST) (No. 2011-0027520).

  1. 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.

  2. Semen quality before cryopreservation and after thawing in 543 patients with testicular cancer

    Science.gov (United States)

    MacKenna, Antonio; Crosby, Javier; Huidobro, Cristián; Correa, Eduardo; Duque, Gonzalo

    2017-01-01

    Objective The main objective of this study was to assess semen characteristics of patients with testicular cancer before cryopreservation and after thawing, to evaluate the consequences of this technique on sperm quality in patients with testicular cancer. Methods Five hundred eighty-nine samples from 543 patients with testicular cancer were cryopreserved between 1995 and 2015, one aliquot per patient was used for a thawing test to assess the impact of cryopreservation on sperm motility; semen analysis was performed before cryo preservation and after thawing, the result interpretation was carried out using the 2010 World Health Organization (WHO) Laboratory Manual, and consent forms were signed by the patients for freezing and when sperm was used for reproductive purposes. Results Hypospermia was observed in 28.7% of samples, the median sperm concentration was 18 million/mL with 35% oligozoospermia; twenty-two patients (4.1%) had azoospermia and 12.7% had severe oligozoospermia, the median sperm count was 31.3 million and 261 semen samples (44.3%) were normal in all parameters according to the WHO; total motile sperm count before cryopreservation and after thawing was 12 (0-412.2) and 7 (0-303.9) million sperm, respectively (p < 0.00001, 95% CI 5.48-14.91), which represents a 32% reduction; concerning the utilization of cryopreserved semen samples, only twelve patients (2.2%) used their frozen sperm for reproductive purposes. Conclusions An impairment in semen quality was found in almost half of the samples from patients with testicular cancer, only few patients had azoospermia or severe oligozoospermia; sperm cryopreservation significantly reduces sperm motility and total motile sperm count and very few patients use their frozen sperm for reproductive purposes. PMID:28333030

  3. Estimation Model of Soil Freeze-Thaw Erosion in Silingco Watershed Wetland of Northern Tibet

    OpenAIRE

    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 S...

  4. Study on dewatering of chemical sludge by freeze-thaw process

    International Nuclear Information System (INIS)

    Xu Shikun; Liu Pin

    1993-01-01

    The treatment of radioactive sludge that is produced from treating radioactive waste water contains radioactively is different from that of non-radioactive sludge. The methods of immersing freeze and simulated two-step freeze have been studied for the elementary properties of simulated low-level radioactive sledge, the effect of freezing temperature, freeze time, and settling time on volume-reduction factor. Some parameters for design of freeze-thaw device are provided

  5. 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.

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

    Science.gov (United States)

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

    2016-12-01

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

  7. 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

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

    Science.gov (United States)

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

    2014-12-01

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

  9. The Relationship between Mechanical Properties and Gradual Deterioration of Microstructures of Rock Mass Subject to Freeze-thaw Cycles

    Directory of Open Access Journals (Sweden)

    Haibo Jiang

    2018-01-01

    Full Text Available Under freeze-thaw cycles, the relationship between rock microstructure deterioration and its macroscopic mechanical characteristics has drawn extensive attention from engineers. With the objective to incorporate freeze-thaw cycle experiment into headrace tunnel engineering, in the present study two groups of andesite rock samples in different states are tested under the conditions of the lowest freezing temperature of –40 ℃ and the thawing temperature of 20 ℃. Damage detection was performed by magnetic resonance imaging for the interior microstructure of rock samples subject to different freeze-thaw cycles, and the relationship between the sample mechanical properties and gradual deterioration of rock microstructures was discussed. The results demonstrate evident influence of freeze-thaw cycle on the damage and deterioration of internal pore structure in andesite, and the rock uniaxial compressive strength and elasticity modulus exhibit a decreasing trend with the increase of freeze-thaw cycles. After 40 cycles, the strength of naturally saturated rock samples decreases by 39.4% (equivalent to 69.4 MPa and the elasticity modulus drops by 47.46% (equivalent to 3.27 GPa. For rock samples saturated by vacuum, 40 freeze-thaw cycles lead to a decrease of 36.86% (equivalent to 58.2 MPa in rock strength and a drop of 44.85% (equivalent to 2.83 GPa in elasticity modulus. Therefore, the test results quantitatively elucidate the substantial influence of freeze-thaw cycle on the damage and deterioration of internal structure in andesite.

  10. The effect of elevated progesterone levels before HCG triggering in modified natural cycle frozen-thawed embryo transfer cycles

    DEFF Research Database (Denmark)

    Groenewoud, Eva R; Macklon, Nick S; Cohlen, Ben J

    2017-01-01

    follicular phase progesterone levels may occur in unstimulated cycles before frozen-thawed embryo transfer, or what affect they may have on outcomes. In this cohort study, 271 patients randomized to the modified natural cycle arm of a randomized controlled trial comparing two endometrial preparation regimens....... Whether monitoring of progesterone and LH in natural cycle frozen-thawed embryo transfer has added clinical value should studied further....

  11. Imprint of thawing scalar fields on the large scale galaxy overdensity

    Science.gov (United States)

    Dinda, Bikash R.; Sen, Anjan A.

    2018-04-01

    We investigate the observed galaxy power spectrum for the thawing class of scalar field models taking into account various general relativistic corrections that occur on very large scales. We consider the full general relativistic perturbation equations for the matter as well as the dark energy fluid. We form a single autonomous system of equations containing both the background and the perturbed equations of motion which we subsequently solve for different scalar field potentials. First we study the percentage deviation from the Λ CDM model for different cosmological parameters as well as in the observed galaxy power spectra on different scales in scalar field models for various choices of scalar field potentials. Interestingly the difference in background expansion results from the enhancement of power from Λ CDM on small scales, whereas the inclusion of general relativistic (GR) corrections results in the suppression of power from Λ CDM on large scales. This can be useful to distinguish scalar field models from Λ CDM with future optical/radio surveys. We also compare the observed galaxy power spectra for tracking and thawing types of scalar field using some particular choices for the scalar field potentials. We show that thawing and tracking models can have large differences in observed galaxy power spectra on large scales and for smaller redshifts due to different GR effects. But on smaller scales and for larger redshifts, the difference is small and is mainly due to the difference in background expansion.

  12. Temporal Behavior of Lake Size-Distribution in a Thawing Permafrost Landscape in Northwestern Siberia

    Directory of Open Access Journals (Sweden)

    Johanna Mård Karlsson

    2014-01-01

    Full Text Available Arctic warming alters regional hydrological systems, as permafrost thaw increases active layer thickness and in turn alters the pathways of water flow through the landscape. Further, permafrost thaw may change the connectivity between deeper and shallower groundwater and surface water altering the terrestrial water balance and distribution. Thermokarst lakes and wetlands in the Arctic offer a window into such changes as these landscape elements depend on permafrost and are some of the most dynamic and widespread features in Arctic lowland regions. In this study we used Landsat remotely sensed imagery to investigate potential shifts in thermokarst lake size-distributions, which may be brought about by permafrost thaw, over three distinct time periods (1973, 1987–1988, and 2007–2009 in three hydrological basins in northwestern Siberia. Results revealed fluctuations in total area and number of lakes over time, with both appearing and disappearing lakes alongside stable lakes. On the whole basin scales, there is no indication of any sustained long-term change in thermokarst lake area or lake size abundance over time. This statistical temporal consistency indicates that spatially variable change effects on local permafrost conditions have driven the individual lake changes that have indeed occurred over time. The results highlight the importance of using multi-temporal remote sensing data that can reveal complex spatiotemporal variations distinguishing fluctuations from sustained change trends, for accurate interpretation of thermokarst lake changes and their possible drivers in periods of climate and permafrost change.

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

    Directory of Open Access Journals (Sweden)

    Ran Wei

    2017-04-01

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

  14. 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.

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

    International Nuclear Information System (INIS)

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

    2013-01-01

    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. (letter)

  16. Microbial network, phylogenetic diversity and community membership in the active layer across a permafrost thaw gradient.

    Science.gov (United States)

    Mondav, Rhiannon; McCalley, Carmody K; Hodgkins, Suzanne B; Frolking, Steve; Saleska, Scott R; Rich, Virginia I; Chanton, Jeff P; Crill, Patrick M

    2017-08-01

    Biogenic production and release of methane (CH 4 ) from thawing permafrost has the potential to be a strong source of radiative forcing. We investigated changes in the active layer microbial community of three sites representative of distinct permafrost thaw stages at a palsa mire in northern Sweden. The palsa site (intact permafrost and low radiative forcing signature) had a phylogenetically clustered community dominated by Acidobacteria and Proteobacteria. The bog (thawing permafrost and low radiative forcing signature) had lower alpha diversity and midrange phylogenetic clustering, characteristic of ecosystem disturbance affecting habitat filtering. Hydrogenotrophic methanogens and Acidobacteria dominated the bog shifting from palsa-like to fen-like at the waterline. The fen (no underlying permafrost, high radiative forcing signature) had the highest alpha, beta and phylogenetic diversity, was dominated by Proteobacteria and Euryarchaeota and was significantly enriched in methanogens. The Mire microbial network was modular with module cores consisting of clusters of Acidobacteria, Euryarchaeota or Xanthomonodales. Loss of underlying permafrost with associated hydrological shifts correlated to changes in microbial composition, alpha, beta and phylogenetic diversity associated with a higher radiative forcing signature. These results support the complex role of microbial interactions in mediating carbon budget changes and climate feedback in response to climate forcing. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

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

    Science.gov (United States)

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

    2015-01-01

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

  18. Ancient low-molecular-weight organic acids in permafrost fuel rapid carbon dioxide production upon thaw.

    Science.gov (United States)

    Drake, Travis W; Wickland, Kimberly P; Spencer, Robert G M; McKnight, Diane M; Striegl, Robert G

    2015-11-10

    Northern permafrost soils store a vast reservoir of carbon, nearly twice that of the present atmosphere. Current and projected climate warming threatens widespread thaw of these frozen, organic carbon (OC)-rich soils. Upon thaw, mobilized permafrost OC in dissolved and particulate forms can enter streams and rivers, which are important processors of OC and conduits for carbon dioxide (CO2) to the atmosphere. Here, we demonstrate that ancient dissolved organic carbon (DOC) leached from 35,800 y B.P. permafrost soils is rapidly mineralized to CO2. During 200-h experiments in a novel high-temporal-resolution bioreactor, DOC concentration decreased by an average of 53%, fueling a more than sevenfold increase in dissolved inorganic carbon (DIC) concentration. Eighty-seven percent of the DOC loss to microbial uptake was derived from the low-molecular-weight (LMW) organic acids acetate and butyrate. To our knowledge, our study is the first to directly quantify high CO2 production rates from permafrost-derived LMW DOC mineralization. The observed DOC loss rates are among the highest reported for permafrost carbon and demonstrate the potential importance of LMW DOC in driving the rapid metabolism of Pleistocene-age permafrost carbon upon thaw and the outgassing of CO2 to the atmosphere by soils and nearby inland waters.

  19. 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.

  20. Ancient low–molecular-weight organic acids in permafrost fuel rapid carbon dioxide production upon thaw

    Science.gov (United States)

    Drake, Travis W.; Wickland, Kimberly P.; Spencer, Robert G. M.; McKnight, Diane M.; Striegl, Robert G.

    2015-01-01

    Northern permafrost soils store a vast reservoir of carbon, nearly twice that of the present atmosphere. Current and projected climate warming threatens widespread thaw of these frozen, organic carbon (OC)-rich soils. Upon thaw, mobilized permafrost OC in dissolved and particulate forms can enter streams and rivers, which are important processors of OC and conduits for carbon dioxide (CO2) to the atmosphere. Here, we demonstrate that ancient dissolved organic carbon (DOC) leached from 35,800 y B.P. permafrost soils is rapidly mineralized to CO2. During 200-h experiments in a novel high–temporal-resolution bioreactor, DOC concentration decreased by an average of 53%, fueling a more than sevenfold increase in dissolved inorganic carbon (DIC) concentration. Eighty-seven percent of the DOC loss to microbial uptake was derived from the low–molecular-weight (LMW) organic acids acetate and butyrate. To our knowledge, our study is the first to directly quantify high CO2 production rates from permafrost-derived LMW DOC mineralization. The observed DOC loss rates are among the highest reported for permafrost carbon and demonstrate the potential importance of LMW DOC in driving the rapid metabolism of Pleistocene-age permafrost carbon upon thaw and the outgassing of CO2 to the atmosphere by soils and nearby inland waters.

  1. 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.

  2. Stress preconditioning of rooster semen before cryopreservation improves fertility potential of thawed sperm.

    Science.gov (United States)

    Feyzi, S; Sharafi, M; Rahimi, S

    2018-03-22

    Avian semen cryopreservation is not as successful as that seen in mammals. This failure is mostly attributed to unique physiological characteristics of poultry semen that make it susceptible to cryo-damages. Utilization of sublethal oxidative stress for preconditioning of sperm, as an innovative approach, improves the cryo-survival of sperm in certain mammalian species. The purpose of this study was to investigate the effects of preconditioning of rooster semen with sublethal oxidative stress [very low concentrations of nitric oxide (NO)] before cryopreservation on the quality and fertility potential of thawed sperm. Semen samples were collected from 20 roosters, twice a wk, and different concentrations of NO [0 (NO-0), 0.01 (NO-0.01), 0.1 (NO-0.1), 1 (NO-1), 10 (NO-10), and 100 μM (NO-100)] were used to investigate the effects of controlled induction of sublethal stress before semen cryopreservation on the thawed sperm performance. A significantly higher (P 0.05) affected by different concentrations of NO. Sperm exposed to NO-1 produced the highest percentage of viable spermatozoa (Annexin-/PI-), which was significantly different from the other samples. Finally, rate of fertility after artificial insemination was significantly higher (P < 0.05) following treatment with NO-1 compared to NO-0 and NO-0.1. Application of 1 μM NO as a sublethal oxidative stress before cryopreservation of sperm efficiently increased numerous quality indices of thawed sperm as well as its fertility potential.

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

    Science.gov (United States)

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

    2012-02-15

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

  4. 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.

  5. 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.

  6. Microwave freeze-thaw technique of injectable drugs. A review from 1980 to 2014.

    Science.gov (United States)

    Hecq, J-D; Godet, M; Jamart, J; Galanti, L

    2015-11-01

    Microwave freeze-thaw treatment (MFTT) of injectable drugs can support the development of centralized intravenous admixtures services (CIVAS). The aim of the review is to collect information and results about this method. A systematic review of the scientific literature about injectable drug stability studies was performed. The data are presented in a table and describe name of the drug, producer, final concentration, temperature and time of freezing storage, type of microwave oven, thawing power, method of dosage and results after treatment or final long-term storage at 5±3 °C. From 1980 to 2014, 59 drugs were studied by MFTT and the results were presented in 49 publications. Forty papers were presented by 8 teams (2 to 18 by team). The temperatures of freezing storage vary from -70 °C to -10 °C, the time storage from 4 hours to 12 months, the thaw from low to full power. Dosages are mainly made by high performance liquid chromatography. Most of the 59 drugs are stable during and after treatment. Only 3 teams have tested the long-term stability after MFTT, the first for ganciclovir after 7 days, the second for ceftizoxime after 30 days and the third for 19 drugs after 11 to 70 days. This review can help CIVAS to take in charge the productions of ready-to-use injectable drugs. Copyright © 2015 Académie Nationale de Pharmacie. Published by Elsevier Masson SAS. All rights reserved.

  7. Simulation of Soil Frost and Thaw Fronts Dynamics with Community Land Model 4.5

    Science.gov (United States)

    Gao, J.; Xie, Z.

    2016-12-01

    Freeze-thaw processes in soils, including changes in frost and thaw fronts (FTFs) , are important physical processes. The movement of FTFs affects soil water and thermal characteristics, as well as energy and water exchanges between land surface and the atmosphere, and then the land surface hydrothermal process. In this study, a two-directional freeze and thaw algorithm for simulating FTFs is incorporated into the community land surface model CLM4.5, which is called CLM4.5-FTF. The simulated FTFs depth and soil temperature of CLM4.5-FTF compared well with the observed data both in D66 station (permafrost) and Hulugou station (seasonally frozen soil). Because the soil temperature profile within a soil layer can be estimated according to the position of FTFs, CLM4.5 performed better in soil temperature simulation. Permafrost and seasonally frozen ground conditions in China from 1980 to 2010 were simulated using the CLM4.5-FTF. Numerical experiments show that the spatial distribution of simulated maximum frost depth by CLM4.5-FTF has seasonal variation obviously. Significant positive active-layer depth trends for permafrost regions and negative maximum freezing depth trends for seasonal frozen soil regions are simulated in response to positive air temperature trends except west of Black Sea.

  8. Research on the Strength Variation of Root-Clay Systems under Freeze-Thaw Action

    Directory of Open Access Journals (Sweden)

    Lin Yang

    2017-01-01

    Full Text Available The aim of this paper is to study the influence of an effective root system of rhizome plants on the reinforcement of slope soil under freeze-thaw conditions. This study focused on the mechanical properties between roots and clay in the root system of four plant species from different regions of China (northeast, northern, central, and southern areas: Setaria viridis, Eleusine indica, Zoysia japonica, and Carex leucochlora. Based on the interfacial friction effects between the plant roots and the soil, pull-out tests and unconfined compressive strength tests were conducted on the reinforced soil system for varying numbers of freeze-thaw cycles. Several stages of the pull-out process of the root system in clay are explicitly proposed based on the interfacial friction test results. The results showed that the friction effect between Zoysia japonica roots and the soil was the most significant and that these roots had the best reinforcement effect. In contrast, the friction and reinforcement effects between Setaria viridis roots and the soil were the worst, and the resulting unconfined compressive strength was the smallest. However, the freeze-thaw resistance ability of the Setaria viridis and soil system was stronger than that of the Zoysia japonica system.

  9. Physical degradation of membrane electrode assemblies undergoing freeze/thaw cycling: Micro-structure effects

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S. [Fuel Cell Dynamics and Diagnostics Laboratory, Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Research and Development Division, Hyundai Motor Company, Yongin 446-912 (Korea); Mench, M.M. [Fuel Cell Dynamics and Diagnostics Laboratory, Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802 (United States)

    2007-11-22

    The objective of this work is to investigate physical damage of polymer electrolyte fuel cell (PEFC) materials subjected to freeze/thaw cycling. Effects of membrane electrode assembly micro-structures (catalyst layer cracking, membrane thickness, and membrane reinforcement) and diffusion media with micro-porous layers were analyzed by comparing scanning electron microscopy images of freeze/thaw cycled samples (-40 C/70 C) with those of virgin material and thermal cycled samples without freezing (5 C/70 C). Ex situ testing performed in this study has revealed a strong direction for the material choices in the PEFC and confirmed the previous computational model in the literature [S. He, M.M. Mench, J. Electrochem. Soc., 153 (2006) A1724-A1731; S. He, S.H. Kim, M.M. Mench, J. Electrochem. Soc., in press]. Specifically, the membrane electrode assemblies were found to be a source of water that can damage the catalyst layers under freeze/thaw conditions. Damage was found to occur almost exclusively under the channel, and not under the land (the graphite that touches the diffusion media). Conceptually, the best material to mitigate freeze-damage is a crack free virgin catalyst layer on a reinforced membrane that is as thin as possible, protected by a stiff diffusion media. (author)

  10. 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.

  11. Effect of Salvia miltiorrhiza polysaccharides on boar spermatozoa during freezing-thawing.

    Science.gov (United States)

    Shen, Tao; Jiang, Zhong-Liang; Liu, Hong; Li, Qing-Wang

    2015-08-01

    Salvia miltiorrhiza polysaccharides (SMPs) were extracted from S. miltiorrhiza in this study. The aim of the present study was to evaluate the effect of SMP on the motility of boar sperm, including the antioxidant effect of SMP on boar sperm and the effect of SMP on the in vivo fertilizing ability of frozen-thawed boar sperm. Fifty ejaculates from 5 Swagger boars were collected and diluted with an extender, which contained 3% glycerol (v/v) with five concentrations of SMP (0.2, 0.4, 0.6, 0.8, and 1.0mg/mL). The semen was frozen in 0.25mL straws at 1.0×10(9) cells/mL. Sixty gilts were inseminated using fresh semen, frozen semen with 0.4mg/mL of SMP and frozen semen without SMP. The results indicate that the addition of SMP to the extender results in a higher percentage of motile sperm post-thaw (Pextender (Pboar sperm from peroxidative damage and increase sperm motility and litter size during the process of freezing-thawing. The optimal concentration of SMP for the frozen extenders in this study was determined to be 0.4mg/mL. Copyright © 2015. Published by Elsevier B.V.

  12. 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.

  13. 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.

  14. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-02-15

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

  16. Effect of haemolysis and repeated freeze-thawing cycles on wild boar serum antibody testing by ELISA

    Directory of Open Access Journals (Sweden)

    Boadella Mariana

    2011-11-01

    Full Text Available Abstract Background Monitoring wildlife diseases is needed to identify changes in disease occurrence. Wildlife blood samples are valuable for this purpose but are often gathered haemolysed. To maximise information, sera often go through repeated analysis and freeze-thaw cycles. Herein, we used samples of clean and haemolysed Eurasian wild boar (Sus scrofa serum stored at -20°C and thawed up to five times to study the effects of both treatments on the outcome of a commercial ELISA test for the detection of antibodies against Suid Herpesvirus 1 (ADV. Results The estimated prevalence of antibodies against ADV was 50-53% for clean and haemolysed sera. Hence, haemolysis did not reduce the mean observed serum antibody prevalence. However, 10 samples changed their classification after repeated freeze-thawing. This included 3 (15% of the clean sera and 7 (41% of the haemolysed sera. Conclusions We recommend (1 establishing more restrictive cut-off values when testing wildlife sera, (2 recording serum quality prior to sample banking, (3 recording the number of freezing-thawing cycles and (4 store sera in various aliquots to reduce repeated usage. For instance, sera with more than 3 freeze-thaw cycles and a haemolysis of over 3 on a scale of 4 should better be discarded for serum antibody monitoring. Even clean (almost not haemolysed sera should not go through more than 5 freeze-thaw cycles.

  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. Effect of vitamin E and selenium nanoparticles on post-thaw variables and oxidative status of rooster semen.

    Science.gov (United States)

    Safa, Soroush; Moghaddam, Gholamali; Jozani, Raziallah Jafari; Daghigh Kia, Hossein; Janmohammadi, Hossein

    2016-11-01

    This study was conducted to determine the combined effects of adding vitamin E (VitE) and selenium nanoparticle (Nano-Se) as antioxidant supplements to rooster semen extender for freezing. Semen samples were collected from 12 White Leghorn roosters and pooled. Subsequently, the samples were divided into nine equal groups using modified Beltsville extender. Extenders were supplemented with either two amounts of VitE (5 and 10μg/mL) or two amounts of Nano-Se (1% and 2%) or a combination of both VitE and Nano-Se, and no antioxidants extender (control group). Using 5μg/mL VitE and 1% of Nano-Se improved (Prooster semen. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Evaluation of <em>HER2em> Gene Amplification in Breast Cancer Using Nuclei Microarray <em>in em>S>itu em>Hybridization

    Directory of Open Access Journals (Sweden)

    Xuefeng Zhang

    2012-05-01

    Full Text Available Fluorescence<em> em>>in situ em>hybridization (FISH assay is considered the “gold standard” in evaluating <em>HER2/neu (HER2em> gene status. However, FISH detection is costly and time consuming. Thus, we established nuclei microarray with extracted intact nuclei from paraffin embedded breast cancer tissues for FISH detection. The nuclei microarray FISH (NMFISH technology serves as a useful platform for analyzing <em>HER2em> gene/chromosome 17 centromere ratio. We examined <em>HER2em> gene status in 152 cases of invasive ductal carcinomas of the breast that were resected surgically with FISH and NMFISH. <em>HER2em> gene amplification status was classified according to the guidelines of the American Society of Clinical Oncology and College of American Pathologists (ASCO/CAP. Comparison of the cut-off values for <em>HER2em>/chromosome 17 centromere copy number ratio obtained by NMFISH and FISH showed that there was almost perfect agreement between the two methods (κ coefficient 0.920. The results of the two methods were almost consistent for the evaluation of <em>HER2em> gene counts. The present study proved that NMFISH is comparable with FISH for evaluating <em>HER2em> gene status. The use of nuclei microarray technology is highly efficient, time and reagent conserving and inexpensive.

  20. 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)

  1. 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.

  2. 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.

  3. 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.

  4. A New Natural Lactone from <em>Dimocarpus> <em>longan> Lour. Seeds

    Directory of Open Access Journals (Sweden)

    Zhongjun Li

    2012-08-01

    Full Text Available A new natural product named longanlactone was isolated from <em>Dimocarpus> <em>longan> Lour. seeds. Its structure was determined as 3-(2-acetyl-1<em>H>-pyrrol-1-yl-5-(prop-2-yn-1-yldihydrofuran-2(3H-one by spectroscopic methods and HRESIMS.

  5. 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

  6. Fator do plasma seminal associado à integridade de membrana de espermatozóides suínos pós-descongelamento Seminal plasma factor associated to post-thawing swine sperm membrane integrity

    Directory of Open Access Journals (Sweden)

    I. Bianchi

    2008-04-01

    Full Text Available Neste estudo, identificaram-se polipeptídeos associados à integridade da membrana plasmática (IMP de espermatozóides suínos após o processo de congelamento/descongelamento. Por meio do perfil protéico do plasma seminal em SDS-PAGE, observou-se a presença de nove bandas polipeptídicas com pesos moleculares que variaram de 11,97 a 122,52kDa. Detectou-se que uma banda de 26,58kDa esteve associada à baixa IMP (Polypeptides associate to membrane integrity (MI of swine spermatozoa submitted to freezing and thawing were identified. The protein profile of seminal plasma analyzed by SDS-PAGE allowed the identification of nine polypeptide bands with molecular weight ranging from 11.97 to 122.52kDa. One 26.58kDa band was associated with reduced MI (<55%. No associations among other bands and MI were observed. The 26.58kDa factor is associated with reduction of membrane integrity of swine spermatozoa after freezing and thawing.

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

    Directory of Open Access Journals (Sweden)

    S. Zwieback

    2018-02-01

    Full Text Available 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.

  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. 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.

  10. 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.

  11. 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

  12. Freeze-thaw cycles induce content exchange between cell-sized lipid vesicles

    Science.gov (United States)

    Litschel, Thomas; Ganzinger, Kristina A.; Movinkel, Torgeir; Heymann, Michael; Robinson, Tom; Mutschler, Hannes; Schwille, Petra

    2018-05-01

    Early protocells are commonly assumed to consist of an amphiphilic membrane enclosing an RNA-based self-replicating genetic system and a primitive metabolism without protein enzymes. Thus, protocell evolution must have relied on simple physicochemical self-organization processes within and across such vesicular structures. We investigate freeze-thaw (FT) cycling as a potential environmental driver for the necessary content exchange between vesicles. To this end, we developed a conceptually simple yet statistically powerful high-throughput procedure based on nucleic acid-containing giant unilamellar vesicles (GUVs) as model protocells. GUVs are formed by emulsion transfer in glass bottom microtiter plates and hence can be manipulated and monitored by fluorescence microscopy without additional pipetting and sample handling steps. This new protocol greatly minimizes artefacts, such as unintended GUV rupture or fusion by shear forces. Using DNA-encapsulating phospholipid GUVs fabricated by this method, we quantified the extent of content mixing between GUVs under different FT conditions. We found evidence of nucleic acid exchange in all detected vesicles if fast freezing of GUVs at ‑80 °C is followed by slow thawing at room temperature. In contrast, slow freezing and fast thawing both adversely affected content mixing. Surprisingly, and in contrast to previous reports for FT-induced content mixing, we found that the content is not exchanged through vesicle fusion and fission, but that vesicles largely maintain their membrane identity and even large molecules are exchanged via diffusion across the membranes. Our approach supports efficient screening of prebiotically plausible molecules and environmental conditions, to yield universal mechanistic insights into how cellular life may have emerged.

  13. 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.

  14. Application of Freezing and Thawing in Apple (Malus domestica) Juice Extraction.

    Science.gov (United States)

    Nadulski, Rafał; Kobus, Zbigniew; Wilczyński, Kamil; Zawiślak, Kazimierz; Grochowicz, Józef; Guz, Tomasz

    2016-09-28

    The paper presents the results of the research on the impact of enzymatic liquefaction, freezing and thawing on the efficiency of juice pressure extraction from apple pulp and quality of the obtained juices. The research was conducted using three types of pretreatment prior the pressing: crushing and enzymatic liquefaction in temperature of 25 °C, crushing and enzymatic liquefaction in temperature of 45 °C and crushing followed by freezing and thawing of the pulp. The study included three varieties of apples. The juice was obtained using a laboratory basket press. It was determined that the pretreatment of the pulp as well as the varietal characteristics of the fruits have a significant impact on the efficiency of the pressure extraction process. The enzymatic treatment of the pulp, irrespective of the temperature at which it was conducted, significantly increased the efficiency of the process. No effect of the temperature (25 or 45 °C) of enzymatic treatment on the efficiency of the pressure extraction process was found. Pretreatment of the pulp based on freezing and thawing contributes to the increase of efficiency of pressing in the case of two apple cultivars, that is, Idared and Red Delicious. It was showed that total phenolic content, antioxidant activity, the soluble solids content and juice acidity (pH) depend on the pretreatment of the pulp and the varietal characteristics of apples. Following the application of pretreatment of the pulp, an increase was observed in the content of polyphenols and in the antioxidant activity of the juices obtained. © 2016 Institute of Food Technologists®

  15. 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.

  16. 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

  17. Reference Gene Selection in the Desert Plant <em>Eremosparton songoricuem>m>

    Directory of Open Access Journals (Sweden)

    Dao-Yuan Zhang

    2012-06-01

    Full Text Available <em>Eremosparton songoricum em>(Litv. Vass. (<em>E. songoricumem> is a rare and extremely drought-tolerant desert plant that holds promise as a model organism for the identification of genes associated with water deficit stress. Here, we cloned and evaluated the expression of eight candidate reference genes using quantitative real-time reverse transcriptase polymerase chain reactions. The expression of these candidate reference genes was analyzed in a diverse set of 20 samples including various <em>E. songoricumem> plant tissues exposed to multiple environmental stresses. GeNorm analysis indicated that expression stability varied between the reference genes in the different experimental conditions, but the two most stable reference genes were sufficient for normalization in most conditions.<em> EsEFem> and <em>Esα-TUB> were sufficient for various stress conditions, <em>EsEF> and <em>EsACT> were suitable for samples of differing germination stages, and <em>EsGAPDH>and <em>Es>UBQ em>were most stable across multiple adult tissue samples. The <em>Es18Sem> gene was unsuitable as a reference gene in our analysis. In addition, the expression level of the drought-stress related transcription factor <em>EsDREB2em>> em>verified the utility of<em> E. songoricumem> reference genes and indicated that no single gene was adequate for normalization on its own. This is the first systematic report on the selection of reference genes in <em>E. songoricumem>, and these data will facilitate future work on gene expression in this species.

  18. Permafrost thaw strongly reduces allowable CO2 emissions for 1.5°C and 2°C

    Science.gov (United States)

    Kechiar, M.; Gasser, T.; Kleinen, T.; Ciais, P.; Huang, Y.; Burke, E.; Obersteiner, M.

    2017-12-01

    We quantify how the inclusion of carbon emission from permafrost thaw impacts the budgets of allowable anthropogenic CO2 emissions. We use the compact Earth system model OSCAR v2.2 which we expand with a permafrost module calibrated to emulate the behavior of the complex models JSBACH, ORCHIDEE and JULES. When using the "exceedance" method and with permafrost thaw turned off, we find budgets very close to the CMIP5 models' estimates reported by IPCC. With permafrost thaw turned on, the total budgets are reduced by 3-4%. This corresponds to a 33-45% reduction of the remaining budget for 1.5°C, and a 9-13% reduction for 2°C. When using the "avoidance" method, however, permafrost thaw reduces the total budget by 3-7%, which corresponds to reductions by 33-56% and 56-79% of the remaining budget for 1.5°C and 2°C, respectively. The avoidance method relies on many scenarios that actually peak below the target whereas the exceedance method overlooks the carbon emitted by thawed permafrost after the temperature target is reached, which explains the difference. If we use only the subset of scenarios in which there is no net negative emissions, the permafrost-induced reduction in total budgets rises to 6-15%. Permafrost thaw therefore makes the emission budgets strongly path-dependent. We also estimate budgets of needed carbon capture in scenarios overshooting the temperature targets. Permafrost thaw strongly increases these capture budgets: in the case of a 1.5°C target overshot by 0.5°C, which is in line with the Paris agreement, about 30% more carbon must be captured. Our conclusions are threefold. First, inclusion of permafrost thaw systematically reduces the emission budgets, and very strongly so if the temperature target is overshot. Second, the exceedance method, that is the only one that complex models can follow, only partially accounts for the effect of slow non-linear processes such as permafrost thaw, leading to overestimated budgets. Third, the newfound

  19. 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.

  20. The Critical Depth of Freeze-Thaw Soil under Different Types of Snow Cover

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    Qiang Fu

    2017-05-01

    Full Text Available Snow cover is the most common upper boundary condition influencing the soil freeze-thaw process in the black soil farming area of northern China. Snow is a porous dielectric cover, and its unique physical properties affect the soil moisture diffusion, heat conduction, freezing rate and other variables. To understand the spatial distribution of the soil water-heat and the variable characteristics of the critical depth of the soil water and heat, we used field data to analyze the freezing rate of soil and the extent of variation in soil water-heat in a unit soil layer under bare land (BL, natural snow (NS, compacted snow (CS and thick snow (TS treatments. The critical depth of the soil water and heat activity under different snow covers were determined based on the results of the analysis, and the variation fitting curve of the difference sequences on the soil temperature and water content between different soil layers and the surface 5-cm soil layer were used to verify the critical depth. The results were as follows: snow cover slowed the rate of soil freezing, and the soil freezing rate under the NS, CS and TS treatments decreased by 0.099 cm/day, 0.147 cm/day and 0.307 cm/day, respectively, compared with that under BL. In addition, the soil thawing time was delayed, and the effect was more significant with increased snow cover. During freeze-thaw cycles, the extent of variation in the water and heat time series in the shallow soil was relatively large, while there was less variation in the deep layer. There was a critical stratum in the vertical surface during hydrothermal migration, wherein the critical depth of soil water and heat change gradually increased with increasing snow cover. The variance in differences between the surface layer and both the soil water and heat in the different layers exhibited “steady-rising-steady” behavior, and the inflection point of the curve is the critical depth of soil freezing and thawing. This critical

  1. Assessment of follicle viability using fluorescence microscopy before and after ovarian thawing.

    Science.gov (United States)

    Sofoudis, C; Zervomanolakis, I; Galani, I; Grigoriou, V; Botsis, D; Vlahos, N

    2017-01-01

    The incidence of young women diagnosed with cancer has been globally increasing. In many cases the surgical approach followed by chemotherapy, radiotherapy or hormonal therapy could lead to infertility or premature ovarian failure. Several options are available in order to preserve fertility and increase the future gestation rate. Among embryo cryopreservation and oocyte cryopreservation, ovarian tissue cryopreservation represents an ideal option, especially for premenopausal women and for those who cannot delay the start of chemotherapy. The purpose of this study was to examine the follicle viability using fluorescence microscope before and after ovarian thawing.

  2. Effects of addition of sodium lauryl sulfate on frozen-thawed canine spermatozoa.

    Science.gov (United States)

    Hori, Tatsuya; Kaseki, Hanae; Fukuhara, Youko; Oba, Hiromichi; Mizutani, Tatsuji; Kawakami, Eiichi; Tsutsui, Toshihiko

    2006-10-01

    The addition of Orvus ES paste (OEP) to extender may be essential for preparing frozen dog semen. The major ingredient of OEP is sodium lauryl sulfate (SLS). In this study, we compared the effect of SLS on frozen dog semen with that of OEP. There were no significant differences between the 2-mg/ml SLS group and OEP group concerning sperm motility, viability and the percentage of viable sperm with intact acrosomes after freeze-thawing. These results suggest that the effectiveness of frozen dog semen extender containing 2 mg/ml of SLS is similar effective to that demonstrated for OEP.

  3. Season-induced changes in bovine sperm motility following a freeze-thaw procedure.

    Science.gov (United States)

    Orgal, Shlomo; Zeron, Yoel; Elior, Nili; Biran, David; Friedman, Eran; Druker, Shaked; Roth, Zvi

    2012-01-01

    Decreased conception rate of dairy cows in the summer is mainly associated with the deleterious effects of environmental thermal stress on the female reproductive tract. Here, we suggest that decreased reproductive performance might be partially due to inferior-quality semen. Semen from five representative bulls was collected in summer (August to September) and winter (December to January) and evaluated with a computerized sperm-quality analyzer for bulls (SQA-Vb). No seasonal effect was found in fresh ejaculate, but sperm examined post-thawing showed lower velocity, motility and progressive motility (Pconception rate of dairy cows in summer.

  4. 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

  5. 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

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

    DEFF Research Database (Denmark)

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

    layer as well in the permafrost. These investigations are accompanied by characterization of the carbon, iron and sulfate content in the soil and will be followed by characterization of the microbial community structure. The aim of this study is to get a better understanding of how the availability...... of sulfate and iron and the microbial community structure regulate the production of CO2 and CH4 in thawing permafrost, and to elucidate how the rate of the organic carbon degradation changes with depth in permafrost-affected soils. This study improves our understanding of climate feedback mechanisms...

  7. Development of Steel Fiber-Reinforced Expanded-Shale Lightweight Concrete with High Freeze-Thaw Resistance

    Directory of Open Access Journals (Sweden)

    Mingshuang Zhao

    2018-01-01

    Full Text Available For the popularized structural application, steel fiber-reinforced expanded-shale lightweight concrete (SFRELC with high freeze-thaw resistance was developed. The experimental study of this paper figured out the effects of air-entraining content, volume fraction of steel fibers, and fine aggregate type. Results showed that while the less change of mass loss rate was taken place for SFRELC after 300 freeze-thaw cycles, the relative dynamic modulus of elasticity and the relative flexural strength presented clear trends of freeze-thaw resistance of SFRELC. The compound effect of the air-entraining agent and the steel fibers was found to support the SFRELC with high freeze-thaw resistance, and the mechanisms were explored with the aid of the test results of water penetration of SFRELC. The beneficial effect was appeared from the replacement of lightweight sand with manufactured sand. Based on the test results, suggestions are given out for the optimal mix proportion of SFRELC to satisfy the durability requirement of freeze-thaw resistance.

  8. Test study on relation between thaw-collapse displacement of medium sand and negative friction of single pile

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, G.; Yang, W. [China University of Mining and Technology, Xuzhou (China). College of Architecture and Civil Engineering

    1999-11-01

    Based on simulation tests, the change of thaw-collapse displacement of saturated medium sand and the relation between negative friction of single pile and thaw-collapse displacement are investigated . In the separating ice and thawing stages, the relation between separating ice surface displacement of sample and time is similarly linear, but the displacement is too small in the redistribution stage of grains. Corresponding to these two stages, the displacement of sample grain framework surface can be divided into similarly linear and non-linear factions. The contribution of the non-linear section comes from grain redistribution after thawing. The negative friction of single pile shows good linear relation following the thawing process. But the producing and increasing mechanisms of negative friction are not the same in the two stages. During the stage of grain redistribution, the displacement of sample grain framework surface occupies only 9.7% of the total displacement, while the negative friction has increased by 18% or so. 6 refs., 7 figs.

  9. 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.

  10. [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.

  11. Viability of bovine demi embryo after splitting of fresh and frozen thawed embryo derived from in vitro embryo production

    Directory of Open Access Journals (Sweden)

    M Imron

    2007-06-01

    Full Text Available In vivo embryo production was limited by number of donor, wide variability respond due to superovulation program and also immunoactifity of superovulation hormone (FSH. Splitting technology could be an alternative to increase the number of transferrable embryos into recipien cows. Splitting is done with cutting embryo becoming two equal pieces (called demi embrio base on ICM orientation. The objective of this research was to determine the viability of demi embryo obtained from embryo splitting of fresh and frozen thawed embryo. The results showed that demi embryos which performed blastocoel reexpansion 3 hours after embryo splitting using fresh and frozen thawed embryos were 76.9 and 76.2% respectively. Base on existention of inner cell mass (ICM, the number of demi embryos developed with ICM from fresh and frozen thawed embryos were not significantly different (90.6 and 85.7% respectively. The cell number of demi embryo from fresh embryos splitting was not different compared with those from frozen thawed embryos (36.1 and 35.9 respectively. These finding indicated that embryo splitting can be applied to frozen thawed embryos with certain condition as well as fresh embryos.

  12. 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

    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...... and high when kept at +2 °C, indicating rapid response of microbial activity even after long exposure to low and fluctuating temperatures. Oribatida and Gamasida displayed a higher abundance in controls kept at -2 °C for up to 80 days, compared to controls at +2 °C and the freeze-thaw treatment...

  13. Effect of freeze-thaw cycles on load transfer between the biomineral and collagen phases in bovine dentin

    Energy Technology Data Exchange (ETDEWEB)

    Deymier-Black, A.C., E-mail: AlixDeymier2010@u.northwestern.edu [Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208 (United States); Almer, J.D., E-mail: almer@aps.anl.gov [Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States); Haeffner, D.R., E-mail: haeffner@aps.anl.gov [Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States); Dunand, D.C., E-mail: dunand@northwestern.edu [Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208 (United States)

    2011-10-10

    Stabilization of biological materials by freezing is widespread in the fields of medicine and biomaterials research and yet, in the case of hard biomaterials such as dentin, there is not a good understanding of how such treatments might affect the mechanical properties. The freezing and thawing may have a number of different effects on dentin including formation of cracks in the microstructure and denaturation of the collagen. Using high-energy synchrotron X-ray diffraction, the apparent moduli of bovine dentin samples were measured before and after various numbers of freeze-thaw cycles. It was determined that repeated freezing and thawing has no measurable effect on the hydroxyapatite or fibrillar apparent moduli up to 10 cycles. This confirms that the use of low temperature storage for stabilization of dentin is reasonable in cases where stiffness is a property of importance. Highlights: {yields} Studied the effect of freezing on the load transfer of HAP and fibrils in dentin. {yields} X-ray scattering measured HAP and fibril apparent moduli vs. freezing cycles. {yields} Apparent moduli did not vary significantly between 0 and 10 freeze thaw cycles. {yields} Residual strains imply no widespread cracking due to volumetric expansion of water. {yields} Dentin can be freeze-thawed with no significant effects on elastic properties.

  14. 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.

  15. 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.

  16. Thawed cod fillets spoil less rapidly than unfrozen fillets when stored under modified atmosphere at 2 degrees C.

    Science.gov (United States)

    Guldager, H S; Bøknaes, N; Osterberg, C; Nielsen, J; Dalgaard, P

    1998-09-01

    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 atmospheres with and without added oxygen. The shelf life of 11 to 12 days in the fresh MAP cod was extended to more than 20 days in the thawed MAP cod at 2 degrees C. This shelf life extension was most likely due to the inactivation of the spoilage bacterium Photobacterium phosphoreum during frozen storage as reflected both in chemical analyses and sensory evaluation. In contrast to fresh MAP cod fillets no significant production of trimethylamine occurred and almost no amine odor and taste were detected during 20 days of chill storage of thawed MAP cod fillets. The use of frozen fillets as raw material not only 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.

  17. Effects of freeze-thaw on characteristics of new KMP binder stabilized Zn- and Pb-contaminated soils.

    Science.gov (United States)

    Wei, Ming-Li; Du, Yan-Jun; Reddy, Krishna R; Wu, Hao-Liang

    2015-12-01

    For viable and sustainable reuse of solidified/stabilized heavy metal-contaminated soils as roadway subgrade materials, long-term durability of these soils should be ensured. A new binder, KMP, has been developed for solidifying/stabilizing soils contaminated with high concentrations of heavy metals. However, the effects of long-term extreme weather conditions including freeze and thaw on the leachability and strength of the KMP stabilized contaminated soils have not been investigated. This study presents a systematic investigation on the impacts of freeze-thaw cycle on leachability, strength, and microstructural characteristics of the KMP stabilized soils spiked with Zn and Pb individually and together. For comparison purpose, Portland cement is also tested as a conventional binder. Several series of tests are conducted including the toxicity characteristic leaching procedure (TCLP), modified European Community Bureau of Reference (BCR) sequential extraction procedure, unconfined compression test (UCT), and mercury intrusion porosimetry (MIP). The results demonstrate that the freeze-thaw cycles have much less impact on the leachability and strength of the KMP stabilized soils as compared to the PC stabilized soils. After the freeze-thaw cycle tests, the KMP stabilized soils display much lower leachability, mass loss, and strength loss. These results are assessed based on the chemical speciation of Zn and Pb, and pore size distribution of the soils. Overall, this study demonstrates that the KMP stabilized heavy metal-contaminated soils perform well under the freeze-thaw conditions.

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

    Directory of Open Access Journals (Sweden)

    Ramu A. Subbramanian

    2012-07-01

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

  19. Trehalose improves semen antioxidant enzymes activity, post-thaw quality, and fertility in Nili Ravi buffaloes (Bubalus bubalis).

    Science.gov (United States)

    Iqbal, Sajid; Andrabi, Syed Murtaza Hassan; Riaz, Amjad; Durrani, Aneela Zameer; Ahmad, Nasim

    2016-03-15

    Our objectives were to study the effect of trehalose in extender on (1) antioxidant enzymes profile during cryopreservation (after dilution, before freezing, and after thawing), (2) in vitro quality (after thawing), and (3) in vivo fertility of Nili Ravi buffalo (Bubalus bubalis) bull spermatozoa. Semen samples (n = 20) from four buffalo bulls were diluted in Tris-citric acid-based extender having different concentrations of trehalose (0.0, 15, 30, 45, and 60 mM) and frozen in French straws. At post dilution, profile of sperm catalase (U/mL) was higher (P semen doses cryopreserved in extender containing 30 mM of trehalose than the control. It is concluded that addition of 30-mM trehalose in extender improves the semen antioxidant enzymes activity, post thaw quality, and fertility in Nili Ravi buffaloes. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. 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.

  1. Modeling conductive heat transfer during high-pressure thawing processes: determination of latent heat as a function of pressure.

    Science.gov (United States)

    Denys, S; Van Loey, A M; Hendrickx, M E

    2000-01-01

    A numerical heat transfer model for predicting product temperature profiles during high-pressure thawing processes was recently proposed by the authors. In the present work, the predictive capacity of the model was considerably improved by taking into account the pressure dependence of the latent heat of the product that was used (Tylose). The effect of pressure on the latent heat of Tylose was experimentally determined by a series of freezing experiments conducted at different pressure levels. By combining a numerical heat transfer model for freezing processes with a least sum of squares optimization procedure, the corresponding latent heat at each pressure level was estimated, and the obtained pressure relation was incorporated in the original high-pressure thawing model. Excellent agreement with the experimental temperature profiles for both high-pressure freezing and thawing was observed.

  2. Effect of waxy rice flour and cassava starch on freeze-thaw stability of rice starch gels.

    Science.gov (United States)

    Charoenrein, Sanguansri; Preechathammawong, Nutsuda

    2012-10-01

    Repeatedly frozen and thawed rice starch gel affects quality. This study investigated how incorporating waxy rice flour (WF) and cassava starch (CS) in rice starch gel affects factors used to measure quality. When rice starch gels containing 0-2% WF and CS were subjected to 5 freeze-thaw cycles, both WF and CS reduced the syneresis in first few cycles. However CS was more effective in reducing syneresis than WF. The different composite arrangement of rice starch with WF or CS caused different mechanisms associated with the rice starch gel retardation of retrogradation, reduced the spongy structure and lowered syneresis. Both swollen granules of rice starch and CS caused an increase in the hardness of the unfrozen and freeze-thawed starch gel while highly swollen WF granules caused softer gels. These results suggested that WF and CS were effective in preserving quality in frozen rice starch based products. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Influence of freeze-thaw cycling on the resilient modulues of PFBC materials

    Energy Technology Data Exchange (ETDEWEB)

    Wolfe, W.E.; Butalia, T.S.; Meek, B.L. [Ohio State University, Columbus, OH (United States). Dept. of Civil and Environmental Engineering and Geodetic Science

    1999-01-01

    The dynamic stress-strain characteristics of a Pressurized Fluidized Bed Combustion (PFBC) material, before and after freeze and thaw cycling, were studied to evaluate its suitability as a substitute for conventional road construction materials in the design of flexible pavement systems. Samples compacted in the laboratory at two different moisture contents (optimum and 8% above optimum) were cyclically load tested after being allowed to cure for various duration. The results of the cyclic tests are presented in terms of the Resilient Modulus, which is a measure of the elastic property of the soil supporting the roadway. The modulus of the samples compacted near the optimum moisture content compared satisfactorily with data available for conventional materials. Samples compacted at moisture contents higher than the optimum exhibited a significant reduction in a resilient modulus values after freeze-thaw cycling. This comparing indicates that properly compacted PFBC holds good promise as a subgrade material in the construction of low traffic volume roads. 13 refs., 5 figs., 1 tab.

  4. Experimental Study Regarding the Freezing and Thawing Dynamics of Spruce Wood

    Directory of Open Access Journals (Sweden)

    Maria - Bernadett SZMUTKU

    2013-03-01

    Full Text Available The article presents the results regarding theevolution of the temperature field in spruce wood(Picea abies L. during freezing at two differentfreezing rates: -100C/h (rapid freezing and -10C/h(slow freezing and then during thawing at +50C,+30°C, +50°C temperature.This approach aimed at simulating thetemperature variations which occur inside timberduring open air storage in winter in two situations(sudden vs. gradual drop of temperature, and thenwhen the timber enters the drying kiln, depending onthe temperature applied in the initial heating phase.The results clearly show that the freezing ratesignificantly influences the thawing time and speed,which increase by 13-17% in the case of slowly frozenwood (at -10C/min compared to rapidly frozen wood(at -100C/min. It was also established that theoptimum temperature in the heating-up phase whendrying frozen spruce is 300C instead of the usual500C. This value leads to much better dryinguniformity without significantly prolonging the dryingtime.

  5. Dissolved organic carbon biodegradability from thawing permafrost stimulated by sunlight rather than inorganic nitrogen

    Science.gov (United States)

    Liu, F.; Chen, L.; Zhang, B.; Wang, G.; Qin, S.; Yang, Y.

    2017-12-01

    Permafrost thaw could result in a large portion of frozen carbon being laterally transferred to aquatic ecosystems as dissolved organic carbon (DOC). During this delivery process, the size of biodegradable DOC (BDOC) determines the proportion of DOC mineralized by microorganisms and associated carbon loss to the atmosphere, which may further trigger positive carbon-climate feedback. Thermokarst is an abrupt permafrost thaw process that can enhance DOC export and also impact DOC processing through increased inorganic nitrogen (N) and sunlight exposure. However, it remains unclear how thermokarst-impacted BDOC responds to inorganic N addition and ultraviolet (UV) light irradiation. Here we explored the responses of DOC concentration, composition and its biodegradability to inorganic N and UV light in a typical thermokarst on the Tibetan Plateau, by combining field observation and laboratory incubation with spectra analyses (UV-visible absorption and three-dimensional fluorescence spectra) and parallel factor analyses. Our results showed that BDOC in thermokarst feature outflows was significantly higher than in reference water. Furthermore, inorganic N addition had no influence on thermokarst-impacted BDOC, whereas exposure to UV light significantly increased BDOC by as much as 2.3 times higher than the dark-control. Moreover, N addition and UV irradiation did not generate additive effects on BDOC. These results imply that sunlight rather than inorganic N can increase thermokarst-derived BDOC, potentially strengthening the positive permafrost carbon-climate feedback.

  6. Investigation of freeze/thaw durability in polymer electrolyte fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Soo-Jin; Park, Gu-Gon; Sohn, Young-Jun; Yim, Sung-Dae; Yang, Tae-Hyun; Kim, Chang-Soo [Fuel Cell Research Center, Korea Institute of Energy Research, 102, Gajeong-ro, Yuseong-gu, Daejeon 305-343 (Korea, Republic of); Park, Jin-Soo [Department of Environmental Engineering, College of Engineering, Sanmyung University, 300 Anseo-dong, Dongnam-gu, Cheonam, Chungnam Province 330-720 (Korea, Republic of); Hong, Bo Ki [Fuel Cell Vehicle Team 1, Ecotechnology Center, Hyundai-Kia Motors Company, 104, Mabuk-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-912 (Korea, Republic of)

    2010-12-15

    This study aims to investigate the effect of different gas diffusion layers (GDLs) on freeze/thaw condition durability in polymer electrolyte fuel cells (PEFCs). Three kinds of GDLs-cloth, felt and paper type - with similar basic properties except thickness and bending stiffness were used. The changes in the properties and cell performance were investigated from the -30 to 70 C range of freeze/thaw cycles. The I-V performance degradation was observed to be negligible for the felt GDL whereas the cloth and paper GDLs showed a marked I-V performance loss. No distinctive correlation between the changes in electrochemical properties, such as active metal surface area, hydrogen crossover rates and decreased I-V performance, was observed except an increase in ohmic resistance revealed by ac-impedance spectroscopy. The physical destruction of electrodes was also shown by scanning electron microscope (SEM) analysis. The present study found that sufficient mechanical supporting force between the interfaces of materials enhances PEFC durability in sub-zero temperature conditions. (author)

  7. 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 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.

  8. 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.

  9. 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. 

  10. Is group A thawed plasma suitable as the first option for emergency release transfusion? (CME).

    Science.gov (United States)

    Chhibber, Vishesh; Greene, Mindy; Vauthrin, Michelle; Bailey, Jeff; Weinstein, Robert

    2014-07-01

    Group AB plasma, which lacks anti-A and anti-B isohemagglutinins, is issued for emergency transfusion when a patient's ABO group is unknown, but the relative scarcity of group AB blood donors limits its availability. We sought to establish a thawed plasma inventory to improve the rapid availability of plasma in the emergency release setting but were concerned about potential wastage of group AB plasma. Recognizing that plasma-incompatible apheresis platelets are routinely transfused and only rarely result in hemolytic reactions if the donor is blood group O, and considering that group A plasma would be compatible with approximately 85% of our patient population, we instituted an emergency release policy whereby thawed group A plasma is issued to all patients of unknown blood group or if compatible plasma is not available. ABO-compatible plasma is then issued, if needed, once the patient's blood group is determined. We prospectively assessed the outcomes of all patients who received incompatible plasma under our policy. During the first 5 years under this policy, 385 emergency release requests for plasma were received by our blood bank. Among them, 23 group B or AB patients met criteria for receiving a median of 2 units of incompatible group A plasma. No hemolytic transfusion reactions or other adverse events related to transfusion were seen in any of these 23 patients. We propose that group A plasma may be an acceptable alternative to AB plasma as the first option in the emergency release setting. © 2014 AABB.

  11. 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.

  12. Magnetic thaw-down and boil-off due to magneto acceptors in 2DEG

    International Nuclear Information System (INIS)

    Chaubet, C.; Raymond, A.; Bisotto, I.; Harmand, J. C.; Kubisa, M.; Zawadzki, W.

    2013-01-01

    The Quantum Hall Effect (QHE) and Shubnikov-de Haas effect are investigated experimentally using n type modulation-doped GaAs/GaAlAs quantum wells (QWs) additionally doped in the well with beryllium acceptor atoms. It is presently shown that the localized magneto-acceptor (MA) states which possess discrete energies above the corresponding Landau levels (LLs) lead to two observable effects in magneto-transport: magnetic thaw-down and magnetic boil-off of 2D electrons. Both effects are related to the fact that electrons occupying the localized MA states cannot conduct. Thus in the thaw-down effect the electrons fall down from the MA states to the free Landau states. This leads to a shift of the Hall plateau towards higher magnetic fields as a consequence of an increase of the 2D electron density N S . In the boil-off effect the electrons are pushed from the free Landau states to the empty MA states under high enough Hall electric field. This process has an avalanche character leading to a dramatic increase of magneto-resistance, consequence of a decrease of N S

  13. Magnetic thaw-down and boil-off due to magneto acceptors in 2DEG

    Energy Technology Data Exchange (ETDEWEB)

    Chaubet, C.; Raymond, A. [L2C UMR 5221, CNRS-Université Montpellier 2, Place E. Bataillon, 34090 Montpellier cedex 05 (France); Bisotto, I. [LNCMI, UPR 3228, CNRS-INSA-UJF-UPS, BP166, 38042 Grenoble, Cedex 9 (France); Harmand, J. C. [LPN, CNRS, route de Nozay, 91460 Marcoussis (France); Kubisa, M. [Institute of Physics, Wroclaw University of Technology, 50-370 Wroclaw (Poland); Zawadzki, W. [Institute of Physics, Polish Academy of Sciences, 02668 Warsaw (Poland)

    2013-12-04

    The Quantum Hall Effect (QHE) and Shubnikov-de Haas effect are investigated experimentally using n type modulation-doped GaAs/GaAlAs quantum wells (QWs) additionally doped in the well with beryllium acceptor atoms. It is presently shown that the localized magneto-acceptor (MA) states which possess discrete energies above the corresponding Landau levels (LLs) lead to two observable effects in magneto-transport: magnetic thaw-down and magnetic boil-off of 2D electrons. Both effects are related to the fact that electrons occupying the localized MA states cannot conduct. Thus in the thaw-down effect the electrons fall down from the MA states to the free Landau states. This leads to a shift of the Hall plateau towards higher magnetic fields as a consequence of an increase of the 2D electron density N{sub S}. In the boil-off effect the electrons are pushed from the free Landau states to the empty MA states under high enough Hall electric field. This process has an avalanche character leading to a dramatic increase of magneto-resistance, consequence of a decrease of N{sub S}.

  14. Effect of Gynostemma Pentaphyllum polysaccharide on boar spermatozoa quality following freezing-thawing.

    Science.gov (United States)

    Hu, Jian-Hong; Li, Qing-Wang; Zhang, Ting; Jiang, Zhong-Liang

    2009-12-01

    Gynostemma Pentaphyllum Polysaccharide (GPP) was added at concentrations of 0.25, 0.5, 1.0, 1.5 and 2.0 mg/ml to the extenders used to freeze boar semen and its effects on the quality of frozen-thawed sperm were assessed. The sperm motility was significantly higher in the extenders containing 0.25 and 0.5 mg/ml GPP, as compared to other groups (Pextender supplemented with 0.5 mg/ml GPP favored the highest intact membrane and intact acrosome percentages in comparison with other groups (Pextender supplemented with 0.25 and 0.5 mg/ml GPP significantly improved SOD levels, compared to other groups (P>0.05). However, the extenders supplemented with GPP did not cause significant differences in levels of CAT and GSH-Px, compared to the control (P>0.05). In summary, GPP exhibited a dose-related response and the lower concentration produced greater protective effect. According to the standard semen quality parameters and antioxidant activities measured in this study, the concentration of 0.5 mg/ml GPP caused a beneficial cryoprotective effects on the quality of frozen-thawed boar semen. It is proposed that an extender containing 0.5 mg/ml GPP could be used as cryoprotective medium of better efficiency.

  15. Trehalose in glycerol-free freezing extender enhances post-thaw survival of boar spermatozoa

    Science.gov (United States)

    ATHURUPANA, Rukmali; TAKAHASHI, Daisen; IOKI, Sumire; FUNAHASHI, Hiroaki

    2015-01-01

    Cryopreservation of boar semen is still considered suboptimal due to lower fertility as compared with fresh samples when glycerol, a permeating cryoprotectant, is used. Trehalose is a non-permeable cryoprotectant and nonreducing disaccharide known to stabilize proteins and biologic membranes. The aim of this study was to evaluate the cryosurvival and in vitro penetrability of boar spermatozoa when glycerol was replaced with trehalose in a freezing extender. Ejaculated Berkshire semen samples were diluted in egg yolk-based freezing extender containing glycerol (100 mM) or trehalose (0, 50, 100, 150, 200 and 250 mM) and cryopreserved using a straw freezing procedure. Thawed samples were analyzed for motility, viability, mitochondrial membrane potential (MMP), and acrosome integrity. In experiment 2, penetrability of spermatozoa cryopreserved with 100 mM glycerol or trehalose was examined. Replacement of cryoprotectant glycerol (100 mM) with trehalose had no effect on sperm viability, but replacing it with 100 mM trehalose improved motility, MMP and acrosome integrity significantly. Sperm motility and MMP were considerably higher in 100 mM trehalose, whereas the acrosome integrity was substantially higher in 100–250 mM trehalose. The in vitro penetration rate was also significantly higher in spermatozoa cryopreserved with trehalose (61.3%) than in those cryopreserved with glycerol (43.6%). In conclusion, 100 mM non-permeable trehalose can be used to replace glycerol, a permeating cryoprotectant, for maintenance of better post-thaw quality of boar spermatozoa. PMID:25754239

  16. Freeze/Thaw-Induced Deformation Monitoring and Assessment of the Slope in Permafrost Based on Terrestrial Laser Scanner and GNSS

    Directory of Open Access Journals (Sweden)

    Lihui Luo

    2017-02-01

    Full Text Available Most previous studies of the Qinghai-Tibet engineering corridor (QTEC have focused on the impacts of climate change on thaw-induced slope failures, whereas few have considered freeze-induced slope failures. Terrestrial laser scanning was used in combination with global navigation satellite systems to monitor three-dimensional surface changes between 2014 and 2015 on the slope of permafrost in the QTEC, which experienced two thawing periods and a freezing period. Soil temperature and moisture sensors were also deployed at 11 depths to reveal the hydrological–thermal dynamics of the active layer. We analyzed scanned surface changes in the slope based on comparisons of multi-temporal point cloud data to determine how the hydrological–thermal process affected active layer deformation during freeze–thaw cycles, thereby comprehensively quantifying the surface deformation. During the two thawing periods, the major structure of the slope exhibited subsidence trends, whereas the major structure of the slope had an uplift trend in the freezing period. The seasonal subsidence trend was caused by thaw settlement and the seasonal uplift trend was probably due to frost heaving. This occurred mainly because the active layer and the upper permafrost underwent a phase transition due to heat transfer. The ground movements occurred approximately in the soil temperature conduction direction between the top of the soil and the permafrost table. The elevation deformation range was mainly −0.20 m to 0.20 m. Surface volume increases with heaving after freezing could have compensated for the loss of thawing twice and still led to the upward swelling of the slope. Thus, this type of slope in permafrost is dominated by frost heave. Deformation characteristics of the slope will support enhanced decision making regarding the implementation of remote sensing and hydrological–thermal measurement technologies to monitor changes in the slopes in permafrost adjacent to

  17. The effect of kinds and concentration of cryoprotectant and thawing methods on frozen semen of Arab chicken

    Directory of Open Access Journals (Sweden)

    Sofjan Iskandar

    2006-03-01

    Full Text Available The success of freezing chicken semen is the hope for preserving Indonesian native chickens. Semen from twenty Arab roosters were collected using massage technique once in a week. Cryoprotectant DMA (dimethyl acetamide or DMF (dimethyl formalmide of 7 or 9% and thawing A at temperature of 30oC for 30 seconds or in B at 5oC for 5 minutes. The volume of fresh semen was 0.3 ± 0.072 ml/ejaculate, white colour, rather thick to thick, with 2200 ± 372 millions sperms/ml and pH 6.95 ± 0.32, 4+/3+ mass movement, 80% motility, 84 ± 4.48% and abnormality of 14.75 ± 1.28%. There were not statistically significant (P>0.05 effect of interaction of treatments (kinds and concentrations of cryoprotectant, and thawing methods on motility and live-sperms. Sperm motility preserved with DMA (34.69% significantly higher than with DMF (29.84%. Sperm motility was also significantly higher (34.53% when preserved with 7% cryoprotectant than with 9% (30%. Thawing-A significantly gave higher motility (35.31% than thawing-B did (29.22%. Live-sperms of semen preserved with DMA (46.75% was significantly higher than with DMF (41.72%. Cryoprotectant concentration of 7% gave higher live-sperms (46.98% than of 9% did (41.48%. Thawing-A left live-sperms of 47.14%, which was significantly higher than thawing-B did (41.30%.

  18. Balancing risk and benefit: maintenance of a thawed Group A plasma inventory for trauma patients requiring massive transfusion.

    Science.gov (United States)

    Mehr, Chelsea R; Gupta, Rajan; von Recklinghausen, Friedrich M; Szczepiorkowski, Zbigniew M; Dunbar, Nancy M

    2013-06-01

    Transfusion of plasma and red blood cell (RBC) units in a balanced ratio approximating 1:1 has been shown in retrospective studies to be associated with improved outcomes for trauma patients. Our low-volume rural trauma center uses a trauma-activated transfusion algorithm. Plasma is thawed upon activation to avoid wastage. However, the time required for plasma thawing has made achievement of a 1:1 ratio early in resuscitation challenging. In this study, the time required for plasma thawing is characterized, and a potential solution is proposed. A retrospective chart study of 38 moderately and massively transfused (≥6 U in the first 24 hours) trauma patients admitted from January 2008 to March 2012 was performed. We evaluated the time required to dispense plasma and the number of RBCs dispensed before plasma in these patients. The average time between the dispense of RBCs and plasma was 26 minutes (median, 28; range, 0-48 minutes). The average number of RBCs dispensed before plasma was 8 U (median, 7 U; range, 0-24 U). Nearly one third of massively transfused patients had 10 RBCs or greater dispensed before plasma was available. There exists the potential for delayed plasma availability owing to time required for thawing, which may compromise the ability to provide balanced plasma to RBC transfusion to trauma patients. Maintenance of a thawed Group AB plasma inventory may not be operationally feasible for rural centers with low trauma volumes. Use of a thawed Group A plasma inventory is a potential alternative to ensure rapid plasma availability. Therapeutic study, level V.

  19. 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

  20. Evaluation, including effects of storage and repeated freezing and thawing, of a method for measurement of urinary creatinine

    DEFF Research Database (Denmark)

    Garde, A H; Hansen, Åse Marie; Kristiansen, J

    2003-01-01

    The aims of this study were to elucidate to what extent storage and repeated freezing and thawing influenced the concentration of creatinine in urine samples and to evaluate the method for determination of creatinine in urine. The creatinine method was based on the well-known Jaffe's reaction...... and measured on a COBAS Mira autoanalyser from Roche. The main findings were that samples for analysis of creatinine should be kept at a temperature of -20 degrees C or lower and frozen and thawed only once. The limit of detection, determined as 3 x SD of 20 determinations of a sample at a low concentration (6...

  1. 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.

  2. Synthesis, Crystal Structure and Luminescent Property of Cd (II Complex with <em>N-Benzenesulphonyl-L>-leucine

    Directory of Open Access Journals (Sweden)

    Xishi Tai

    2012-09-01

    Full Text Available A new trinuclear Cd (II complex [Cd3(L6(2,2-bipyridine3] [L =<em> Nem>-phenylsulfonyl-L>-leucinato] has been synthesized and characterized by elemental analysis, IR and X-ray single crystal diffraction analysis. The results show that the complex belongs to the orthorhombic, space group<em> Pem>212121 with<em> aem> = 16.877(3 Å, <em>b> em>= 22.875(5 Å, <em>c em>= 29.495(6 Å, <em>α> em>= <emem>= <emem>= 90°, <em>V> em>= 11387(4 Å3, <em>Z> em>= 4, <em>Dc>= 1.416 μg·m−3, <emem>= 0.737 mm−1, <em>F> em>(000 = 4992, and final <em>R>1 = 0.0390, <em>ωR>2 = 0.0989. The complex comprises two seven-coordinated Cd (II atoms, with a N2O5 distorted pengonal bipyramidal coordination environment and a six-coordinated Cd (II atom, with a N2O4 distorted octahedral coordination environment. The molecules form one dimensional chain structure by the interaction of bridged carboxylato groups, hydrogen bonds and p-p interaction of 2,2-bipyridine. The luminescent properties of the Cd (II complex and <em>N-Benzenesulphonyl-L>-leucine in solid and in CH3OH solution also have been investigated.

  3. 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...

  4. 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

  5. Observations on procedures for thawing and spit-roasting frozen dressed chickens, and post-cooking care and storage: with particular reference to food-poisoning bacteria

    Science.gov (United States)

    Roberts, Diane

    1972-01-01

    A comparison was made of four methods of thawing frozen chickens and an average thaw time for each method was determined. Fully and partially thawed chickens, inoculated with salmonellas, Clostridium welchii and Staphylococcus aureus were cooked in a spit-roasting oven at different temperatures for different lengths of time. The chickens were examined freshly cooked and after storage under various conditions. Spit roasting fully thawed chickens until the outer skin was golden brown was sufficient heat-treatment to kill salmonellas and Staph. aureus but Cl. welchii could survive. Salmonellas could also survive if the chickens were not fully thawed before cooking. Incorrect storage after cooking was shown to encourage the growth of pathogens. The incidence of intestinal pathogens in frozen dressed chickens and environmental hazards in spit-roasting establishments were also studied. Of raw chickens examined 35% contained salmonellas (9 serotypes), 63% contained Cl. welchii and 63% Staph. aureus. PMID:4342001

  6. Tracer-based identification of rock glacier thawing in a glacierized Alpine catchment

    Science.gov (United States)

    Engel, Michael; Penna, Daniele; Tirler, Werner; Comiti, Francesco

    2017-04-01

    Current warming in high mountains leads to increased melting of snow, glacier ice and permafrost. In particular rock glaciers, as a creeping form of mountain permafrost, may release contaminants such as heavy metals into the stream during intense melting periods in summer. This may have strong impacts on both water quantity and quality of fresh water resources but might also harm the aquatic fauna in mountain regions. In this context, the present study used stable isotopes of water and electrical conductivity (EC) combined with trace, major and minor elements to identify the influence of permafrost thawing on the water quality in the glacierized Solda catchment (130 km2) in South Tyrol (Italy). We carried out a monthly sampling of two springs fed by an active rock glacier at about 2600 m a.s.l. from July to October 2015. Furthermore, we took monthly water samples from different stream sections of the Solda River (1110 to m a.s.l.) from March to November 2015. Meteorological data were measured by an Automatic Weather Station at 2825 m a.s.l. of the Hydrographic Office (Autonomous Province of Bozen-Bolzano). First results show that water from the rock glacier springs and stream water fell along the global meteoric water line. Spring water was slightly more variable in isotopic ratio (δ2H: -91 to - 105 ) and less variable in dissolved solutes (EC: 380 to 611 μS/cm) than stream water (δ2H: -96 to - 107 ‰ and EC: 212 to 927 μS/cm). Both spring water and stream water showed a pronounced drop in EC during July and August, very likely induced by increased melt water dilution. In both water types, element concentrations of Ca and Mg were highest (up to 160 and 20 mg/l, respectively). In September, spring water showed higher concentrations in Cu, As, and Pb than stream water, indicating that these elements partly exceeded the concentration limit for drinking water. These observations highlight the important control, which rock glacier thawing may have on water quality

  7. 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

  8. 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

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

    International Nuclear Information System (INIS)

    Thirumala, Sreedhar; Forman, Julianne M; Monroe, W Todd; Devireddy, Ram V

    2007-01-01

    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 -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 pg (μm/min-atm) and activation energy, E Lp (kcal mol -1 ) were obtained. For HeLa cells, the values of L pg ranged from 0.08 to 0.23 μm/min-atm, while E Lp ranged from 10.9 to 37.4 kcal mol -1 . For Jurkat cells these parameter values ranged from 0.05 to 0.16 μm/min-atm and 9.5 to 35.9 kcal mol -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 -1 , suggesting a possible therapeutic use of NPs in cryodestructive procedures

  10. Quality of Clotting Factor Activity in Fresh Frozen Plasma at Thaw with a Microwave System and after Storage at 4 degrees C for 48 Hours.

    Science.gov (United States)

    Kuta, Piotr; Hauck-Dlimi, Barbara; Strobel, Julian; Zimmermann, Robert; Eckstein, Reinhold

    2016-01-01

    Uncontrolled hemorrhage in polytrauma patients usually results in rapid need of blood products. Despite the shorter thawing times of microwave devices for heating fresh frozen plasma (FFP), their use has remained controversial, and just a few laboratory analyses have been published on this topic. The aim of this study was to analyse the quality of clotting factors immediately after thawing FFP with a microwave device and after 48-hour post thaw storage at 4 degrees C. 24 FFP units of all four ABO blood groups (six of each blood group) were thawed with a Transfusio-therm 2000 and later stored at 4 degrees C for 48 hours. Samples were drawn aseptically and investigated on various clotting factors and protein proteases (fibrinogen, antithrombin, FII, FV, FVII, FVIII, FIX, FX, FXI, FXIII, vWF antigen and activity, protein S, and protein C) using standard coagulation and chromogenic assays immediately after thawing and again after a 48-hour storage period at 4 degrees C. All units were tested for both anaerobic and aerobic microbial contamination using standard operating procedures immediately after thawing. After thawing, all coagulation factors and protein protease activities were within normal ranges. Blood group O individuals had approximately 25% lower plasma levels of vWF antigen and activity. After a 48-hour storage period at 4 degrees C, FVIII and FIX activities declined significantly in all blood groups, whereas the remaining clotting factors remained comparably stable. Immediately after rapid thawing using a microwave system, all FFP units contained adequate coagulation factor activities to maintain hemostatic activity at the time of product thaw. The post thaw refrigerated storage caused an anticipated decrease in factor VIII and IX activities, but retained normal coagulation factor levels of many plasma proteins. Therefore we conclude that the Transfusio-therm 2000 has no clinically significant influence on the activity of clotting factors and plasma

  11. Protein and solute distribution in drug substance containers during frozen storage and post-thawing: a tool to understand and define freezing-thawing parameters in biotechnology process development.

    Science.gov (United States)

    Kolhe, Parag; Badkar, Advait

    2011-01-01

    Active pharmaceutical ingredient for biotechnology-based drugs, commonly known as drug substance (DS), is often stored frozen for longer shelf-life. Freezing DS enhances stability by slowing down reaction rates that lead to protein instability, minimizes the risk of microbial growth, and eliminates the risk of transport-related stress. High density polyethylene bottles are commonly used for storing monoclonal antibody DS due to good mechanical stress/strain resistant properties even at low temperatures. Despite the aforementioned advantages for frozen storage of DS, this is not devoid of risks. Proteins are known to undergo ice-water surface denaturation, cryoconcentration, and cold denaturation during freezing. A systematic investigation was performed to better understand the protein and solute distribution along with potential of aggregate formation during freeze and thaw process. A significant solute and protein concentration gradient was observed for both frozen and thawed DS bottles. In case of thawed DS, cryoconcentration was localized in the bottom layer and a linear increase in concentration as a function of liquid depth was observed. On the other hand, for frozen DS, a "bell shaped" cryoconcentration distribution was observed between the bottom layers and centre position. A cryoconcentration of almost three-fold was observed for frozen DS in the most concentrated part when freezing was conducted at -20 and -40 °C and 2.5-fold cryoconcentration was observed in the thawed DS before mixing. The information obtained in this study is critical to design freeze thaw experiments, storage condition determination, and process improvement in manufacturing environment. Copyright © 2011 American Institute of Chemical Engineers (AIChE).

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

    Directory of Open Access Journals (Sweden)

    Andrea D. Abranches

    2014-07-01

    Full Text Available OBJECTIVES: to analyze the changes in human milk macronutrients: fat, protein, and lactose in natural human milk (raw, frozen and thawed, after administration simulation by gavage and continuous infusion. METHOD: an experimental study was performed with 34 human milk samples. The infrared spectrophotometry using the infrared analysis equipment MilkoScan Minor(r (Foss, Denmark equipment was used to analyze the macronutrients in human milk during the study phases. The analyses were performed in natural (raw samples and after freezing and fast thawing following two steps: gavage and continuous infusion. The non-parametric Wilcoxon test for paired samples was used for the statistical analysis. RESULTS: the fat content was significantly reduced after administration by continuous infusion (p < 0.001 during administration of both raw and thawed samples. No changes in protein and lactose content were observed between the two forms of infusion. However, the thawing process significantly increased the levels of lactose and milk protein. CONCLUSION: the route of administration by continuous infusion showed the greatest influence on fat loss among all the processes required for human milk administration.

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

    Science.gov (United States)

    Abranches, Andrea D; Soares, Fernanda V M; Junior, Saint-Clair G; Moreira, Maria Elisabeth L

    2014-01-01

    to analyze the changes in human milk macronutrients: fat, protein, and lactose in natural human milk (raw), frozen and thawed, after administration simulation by gavage and continuous infusion. an experimental study was performed with 34 human milk samples. The infrared spectrophotometry using the infrared analysis equipment MilkoScan Minor® (Foss, Denmark) equipment was used to analyze the macronutrients in human milk during the study phases. The analyses were performed in natural (raw) samples and after freezing and fast thawing following two steps: gavage and continuous infusion. The non-parametric Wilcoxon test for paired samples was used for the statistical analysis. the fat content was significantly reduced after administration by continuous infusion (praw and thawed samples. No changes in protein and lactose content were observed between the two forms of infusion. However, the thawing process significantly increased the levels of lactose and milk protein. the route of administration by continuous infusion showed the greatest influence on fat loss among all the processes required for human milk administration. Copyright © 2014 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.

  14. 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.

  15. Role of freeze-thaw cycles and chlorpyrifos insecticide use on diffuse Cd loss and sediment accumulation

    Science.gov (United States)

    Wang, Fangli; Ouyang, Wei; Hao, Fanghua; Jiao, Wei; Shan, Yushu; Lin, Chunye

    2016-06-01

    Freeze-thaw cycles are predicted to increase in cold temperate regions. The potential influence of the interactions of freeze-thaw cycles and agrochemicals on the release of Cd into river water is unknown. In this study, the interactions of freeze-thaw cycles and chlorpyrifos (FC) on Cd mobility in soils were analysed. The spatial variability of soil Cd under long-term intensive tillage in a freeze-thaw agro-system was also identified. The temporal variation of sediment Cd was detected based on analysis of the sediment geochemistry. The results showed that FC increased soil Cd mobility, with an increase of approximately 10% in CaCl2-extractable Cd. The increased mobile fractions of water-soluble and exchangeable Cd originated from the decreased fraction of Fe-Mn-oxide-associated Cd and organic matter-bound Cd. The total Cd content in the surface soil followed the zonally decreasing trend of dry land > paddy land > natural land. The Cd concentrations and sedimentation rates of the sediment core generally increased from 1943 to 2013 due to agricultural exploration and farmland irrigation system construction, indicating an increase of the Cd input flux into water. The results provide valuable information about the soil Cd transport response to the influence of climatic and anthropogenic factors in cold intensive agro-systems.

  16. Negative effect of combined cysteine and glutathione in soy lecithin-based extender on post-thawed ram spermatozoa.

    Science.gov (United States)

    Zhandi, Mahdi; Sharafi, Mohsen

    2015-09-01

    This study was conducted to evaluate the effect of combined cysteine and glutathione in soy lecithin-based semen extender on post-thawed ram sperm quality. A total of 28 ejaculates were collected twice a week (from four rams) during breeding season. In each replicate, semen samples (n = 4, one ejaculate for each ram) were pooled and divided into three equal parts, and each part was diluted with one of following extender: (1) soy lecithin-based extender containing no cysteine and no glutathione (C0-G0), (2) soy lecithin-based extender containing cysteine (5 mM) and glutathione (5 mM) (C5-G5), and (3) soy lecithin-based extender containing cysteine (10 mM) and glutathione (10 mM) (C10-G10). After freeze-thawing process, motility and velocity parameters, plasma membrane integrity and functionality, mitochondrial activity, and apoptosis features of spermatozoa were evaluated. The obtained results showed that total and progressive motility, plasma membrane integrity and functionality, and live post-thawed spermatozoa was lower in C10-G10 extender compared to C0-G0 and C5-G5 extenders (P 0.05). In conclusion, it seems that high concentration of combined cysteine and glutathione in soy lecithin-based semen extender has a detrimental effect of post-thawed ram sperm quality.

  17. 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.

  18. 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 (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.

  19. Temporal monitoring of the soil freeze-thaw cycles over snow-cover land by using off-ground GPR

    KAUST Repository

    Jadoon, Khan; Lambot, Sé bastien; Dimitrov, Marin; Weihermü ller, Lutz

    2013-01-01

    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

  20. 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.

  1. 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

  2. The combined effect of freeze thaw events and heavy metal pollution leads to distinct lethal synergy in Enchytraeus albidus

    DEFF Research Database (Denmark)

    Boas, Sara Wincentz; Slotsbo, Stine; Holmstrup, Martin

    Many anthropogenic activities negatively affect the environment and stress the organisms living here in various ways. Due to global warming it is likely that freeze-thaw events will replace permanent freezing of soils in arctic regions. Metals are some of the most common contaminants in soil...

  3. 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

    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...

  4. 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.

  5. 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

  6. 86 successful births and 9 ongoing pregnancies worldwide in women transplanted with frozen-thawed ovarian tissue

    DEFF Research Database (Denmark)

    Jensen, Annette Klüver; Macklon, Kirsten Tryde; Fedder, Jens

    2017-01-01

    Purpose: This study aims to make an account of the children born following transplantation of frozen-thawed ovarian tissue worldwide with specific focus on the perinatal outcome of the children. Furthermore, perinatal outcome of seven deliveries (nine children) from Denmark is reported. Methods...

  7. Spring-Thaw Nitrous Oxide Emissions from Reed Canarygrass on Wetness-Prone Marginal Soil in New York State

    NARCIS (Netherlands)

    Mason, C.; Stoof, C.R.; Richards, B.K.; Rossiter, D.; Steenhuis, T.S.

    2016-01-01

    In temperate climates, a significant fraction of annual emissions of nitrous oxide (N2O) from agricultural land can occur during soil thaw in late winter and early spring. The objective of this study is to determine the impact of land use change from long-term fallow grassland to managed perennial

  8. 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

  9. 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...

  10. The first woman to give birth to two children following transplantation of frozen/thawed ovarian tissue

    DEFF Research Database (Denmark)

    Ernst, Erik; Bergholdt, Stinne; Jørgensen, Jan Stener

    2010-01-01

    Worldwide eight children have been born as a result of transplanting frozen/thawed ovarian tissue. Two of these children were born in Denmark following transport of the ovarian tissue for a period of 5 h prior to cryopreservation. One of these women, who was originally transplanted with six pieces...

  11. Effects of storage in different semen extenders on the pre-freezing and post-thawing quality of boar spermatozoa.

    Science.gov (United States)

    Dziekońska, A; Zasiadczyk, Ł; Lecewicz, M; Strzeżek, R; Koziorowska-Gilun, M; Fraser, L; Mogielnicka-Brzozowska, M; Kordan, W

    2015-01-01

    The aim of this study was to investigate the effects of storage of semen in different commercial extenders on the pre-freezing and post-thawing quality of boar spermatozoa. Semen was diluted in BTS, Androhep (AH) and Gedil (GD), stored for 24 h at 17°C, and then frozen in accordance with the cryopreservation protocol. Analyses of the quality of spermatozoa included: motility, normal apical ridge (NAR) acrosome, plasma membrane integrity (PMI), mitochondrial membrane potential (MMP), measurements of ATP content and activity of superoxidase dismutase (SOD) and glutathione peroxidase (GPx). Prior to the freezing process, no significant effect of the extender on the sperm quality parameters was noted. After thawing the spermatozoa it was demonstrated that the type of extender used influenced PMI, MMP, ATP content and activity of GPx. In the AH extender the percentage of spermatozoa with PMI and ATP content in spermatozoa was significantly higher (Pextenders. In addition, semen stored in the AH was characterised by a statistically higher (Pboar spermatozoa stored for 24 hours in liquid state can be used. However, the type of extender used prior to freezing may have a significant effect on the post-thawing quality of the spermatozoa. The AH extender better secured the quality of thawed boar spermatozoa as compared with the BTS or GD.

  12. Freezing-thawing hysteresis phenomena of biological systems by the new method of proton magnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Eiichiro; Nagashima, Nobuya (Ajinomoto Co. Inc., Kawasaki, Kanagawa (Japan))

    1982-09-01

    an automatic recording system was developed for unfrozen water content and spin-spin relaxation time measurements as continuous functions of temperature, by using a broad-line pulsed NMR spectrometer and a minicomputer. The advantages of this system are that the exact quantitative measurements can be done by calibrating the nonlinearity of the NMR sensitivity, and that for high sensitivity temperature measurement the thermocouple with special device is directly immersed in a sample. Three types of freezing-thawing hysteresis phenomena, (1) recrystallization of solute (hydroxy-L-proline, D-mannitol) and refreezing of released hydrated water molecules in frozen aqueous solutions, and (2) hysteresis as the characteristic feature of gels (gelatin, alpha sub(sl)-casein), and (3) supercooling of capillary water in water-insoluble materials (zein, yeast RNA, cellulose) were analysed. The usefulness of this system as an analytical instrument of hydration properties of biological materials is emphasized.

  13. Freezing-thawing hysteresis phenomena of biological systems by the new method of proton magnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, E.; Nagashima, N.

    1982-01-01

    An automatic recording system was developed for unfrozen water content and spin-spin relaxation time measurements as continuous functions of temperature, by using a broad-line pulsed NMR spectrometer and a mini-computer. The advantages of this system are that the exact quantitative measurements can be done by calibrating the nonlinearity of the NMR sensitivity, and that for high sensitivity temperature measurement the thermocouple with special device is directly immersed in a sample. Three types of freezing-thawing hysteresis phenomena, (1) recrystallization of solute(hydroxy-L-proline, D-mannitol) and refreezing of released hydrated water molecules in frozen aqueous solutions, and (2) hysteresis as the characteristic feature of gels(gelatin, J/sub s1/-casein), and (3) supercooling of capillary water in water-insoluble materials(zein, yeast RNA, cellulose) were analysed. The usefulness of this system as an analytical instrument of hydration properties of biological materials is emphasized.

  14. 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

    Our overall goal in this research was 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 was 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 tested 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. In collaboration with our Purdue and MIT colleagues, we have attempted to quantify global climate warming effects on land-atmosphere interactions, land-river network interactions, permafrost degradation, vegetation shifts, and land use influence water, carbon, and nitrogen fluxes to and from terrestrial ecosystems in the pan-arctic along with their

  15. 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

  16. 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

    Thawing permafrost and the resulting mineralization of previously frozen organic carbon (C) is considered an important future feedback from terrestrial ecosystems to the atmosphere. Here, we use a dynamic process oriented permafrost model, the CoupModel, to link surface and subsurface temperatures....... The model is successfully adjusted and applied for the study area and shown to be able to simulate active layer dynamics. Subsequently, the model is used to predict the active layer thickness under future warming scenarios. The model predicts an increase of maximum active layer thickness from today 70 to 80......–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...

  17. Cost Optimization of Mortars Containing Different Pigments and Their Freeze-Thaw Resistance Properties

    Directory of Open Access Journals (Sweden)

    Sadık Alper Yıldızel

    2016-01-01

    Full Text Available Nowadays, it is common to use colored concrete or mortar in prefabricated concrete and reinforced concrete construction elements. Within the scope of this study, colored mortars were obtained with the addition of brown, yellow, black, and red pigments into the white cement. Those mixtures are examined for their compressive strength, unit weight, water absorption, and freeze-thaw resistance. Subsequent to comparison of these properties, a cost optimization has been conducted in order to compare pigment costs. The outcomes showed that the pore structure in architectural mortar applications plays an important role in terms of durability. And cost optimization results show that light colored minerals can be used instead of white cements.

  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. Freezing-thawing hysteresis phenomena of biological systems by the new method of proton magnetic resonance

    International Nuclear Information System (INIS)

    Suzuki, Eiichiro; Nagashima, Nobuya

    1982-01-01

    an automatic recording system was developed for unfrozen water content and spin-spin relaxation time measurements as continuous functions of temperature, by using a broad-line pulsed NMR spectrometer and a minicomputer. The advantages of this system are that the exact quantitative measurements can be done by calibrating the nonlinearity of the NMR sensitivity, and that for high sensitivity temperature measurement the thermocouple with special device is directly immersed in a sample. Three types of freezing-thawing hysteresis phenomena, (1) recrystallization of solute (hydroxy-L-proline, D-mannitol) and refreezing of released hydrated water molecules in frozen aqueous solutions, and (2) hysteresis as the characteristic feature of gels(gelatin, alpha sub(sl)-casein), and (3) supercooling of capillary water in water-insoluble materials(zein, yeast RNA, cellulose) were analysed. The usefulness of this system as an analytical instrument of hydration properties of biological materials is emphasized. (author)

  20. Monitoring of Freeze-Thaw Cycles in Concrete Using Embedded Sensors and Ultrasonic Imaging

    Science.gov (United States)

    Ranz, Javier; Aparicio, Sofía; Romero, Héctor; Casati, María Jesús; Molero, Miguel; González, Margarita

    2014-01-01

    This paper deals with the study of damage produced during freeze-thaw (F-T) cycles using two non-destructive measurement approaches—the first approach devoted to continuous monitoring using embedded sensors during the cycles, and the second one, performing ultrasonic imaging before and after the cycles. Both methodologies have been tested in two different types of concrete specimens, with and without air-entraining agents. Using the first measurement approach, the size and distribution of pores were estimated using a thermoporometrical model and continuous measurements of temperature and ultrasonic velocity along cycles. These estimates have been compared with the results obtained using mercury porosimetry testing. In the second approach, the damage due to F-T cycles has been evaluated by automated ultrasonic transmission and pulse-echo inspections made before and after the cycles. With these inspections the variations in the dimensions, velocity and attenuation caused by the accelerated F-T cycles were determined. PMID:24481231

  1. Derivation of Rabbit Embryonic Stem Cells from Vitrified–Thawed Embryos

    Science.gov (United States)

    Chen, Chien-Hong; Li, Yi; Hu, Yeshu; An, Li-You; Yang, Lan; Zhang, Jifeng; Chen, Y. Eugene

    2015-01-01

    Abstract The rabbit is a useful animal model for regenerative medicine. We previously developed pluripotent rabbit embryonic stem cell (rbESC) lines using fresh embryos. We also successfully cryopreserved rabbit embryos by vitrification. In the present work, we combined these two technologies to derive rbESCs using vitrified–thawed (V/T) embryos. We demonstrate that V/T blastocysts (BLs) can be used to derive pluripotent rbESCs with efficiencies comparable to those using fresh BLs. These ESCs are undistinguishable from the ones derived from fresh embryos. We tested the developmental capacity of rbESCs derived from V/T embryos by BL injection experiments and produced chimeric kits. Our work adds cryopreservation to the toolbox of rabbit stem cell research and applications and will greatly expand the available research materials for regenerative medicine in a clinically relevant animal model. PMID:26579970

  2. Relative Sensitivity of Photosynthesis and Respiration to Freeze-Thaw Stress in Herbaceous Species 1

    Science.gov (United States)

    Steffen, Kenneth L.; Arora, Rajeev; Palta, Jiwan P.

    1989-01-01

    The relative effect of a freeze-thaw cycle on photosynthesis, respiration, and ion leakage of potato leaf tissue was examined in two potato species, Solanum acaule Bitt. and Solanum commersonii Dun. Photosynthesis was found to be much more sensitive to freezing stress than was respiration, and demonstrated more than a 60% inhibition before any impairment of respiratory function was observed. Photosynthesis showed a slight to moderate inhibition when only 5 to 10% of the total electrolytes had leaked from the tissue (reversible injury). This was in contrast to respiration which showed no impairment until temperatures at which about 50% ion leakage (irreversible injury) had occurred. The influence of freeze-thaw protocol was further examined in S. acaule and S. commersonii, in order to explore discrepancies in the literature as to the relative sensitivities of photosynthesis and respiration. As bath cooling rates increased from 1°C/hour to about 3 or 6°C/hour, there was a dramatic increase in the level of damage to all measured cellular functions. The initiation of ice formation in deeply supercooled tissue caused even greater damage. As the cooling rates used in stress treatments increased, the differential sensitivity between photosynthesis and respiration nearly disappeared. Examination of agriculturally relevant, climatological data from an 11 year period confirmed that air cooling rates in the freezing range do not exceed 2°C/hour. It was demonstrated, in the studies presented here, that simply increasing the actual cooling rate from 1.0 to 2.9°C/hour, in frozen tissue from paired leaflet halves, meant the difference between cell survival and cell death. Images Figure 4 Figure 5 PMID:16666712

  3. Hydroxyethyl starch as a substitute for dextran 40 for thawing peripheral blood progenitor cell products.

    Science.gov (United States)

    Zhu, Fenlu; Heditke, Sarah; Kurtzberg, Joanne; Waters-Pick, Barbara; Hari, Parameswaran; Margolis, David A; Keever-Taylor, Carolyn A

    2015-12-01

    Removing DMSO post-thaw results in: reduced infusion reactions, improved recovery and stability of viable CD34+ cells. Validated methods use 5%-8.3% Dextran 40 with 2.5%-4.2% HSA for this purpose. Recent shortages of clinical grade Dextran require identification of suitable alternatives. PBPC were used to compare a standard 2X wash medium of 5 parts 10% Dextran 40 in saline (DEX) with 1 part 25% HSA (8.3% DEX/ 4.2% HSA) with Hydroxyethyl Starch (HES)-based solutions. Cells in replicate bags were diluted with an equal volume of wash solution, equilibrated 5 minutes, the bag filled with wash medium, pelleted and the supernatant expressed. Bags were restored to the frozen volume in wash medium and tested by single platform flow cytometry and CFU. Total viability, viable TNC, MNC, and CD34+ cell recovery, and CD34+ cell viability were compared immediately post-thaw and after 90 minutes. 5.2% HES/4.2% HSA did not differ from our standard in CD34 recovery or viability. Due to concerns that high concentrations of HES could affect renal function we tested 0.6% HES/2.5% HSA resulting in significantly poorer CD34 recovery and viability. Results improved using 2.4% HES/4.2% HSA and when 0.6% HES/4.2%HSA was used no significant differences were seen. CFU assays confirmed no differences between the standard dextran arm and HES at 2.4% or 0.6% so long as HSA was at 4.2%. We conclude that HES from 0.6% to 5.2% with 4.2% HSA is a suitable substitute for Dextran 40 as a reconstitution/washing medium for PBPC products. Copyright © 2015 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.

  4. Effects of soil rewetting and thawing on soil gas fluxes: a review of current literature and suggestions for future research

    Directory of Open Access Journals (Sweden)

    D.-G. Kim

    2012-07-01

    Full Text Available The rewetting of dry soils and the thawing of frozen soils are short-term, transitional phenomena in terms of hydrology and the thermodynamics of soil systems. The impact of these short-term phenomena on larger scale ecosystem fluxes is increasingly recognized, and a growing number of studies show that these events affect fluxes of soil gases such as carbon dioxide (CO2, methane (CH4, nitrous oxide (N2O, ammonia (NH3 and nitric oxide (NO. Global climate models predict that future climatic change is likely to alter the frequency and intensity of drying-rewetting events and thawing of frozen soils. These future scenarios highlight the importance of understanding how rewetting and thawing will influence dynamics of these soil gases. This study summarizes findings using a new database containing 338 studies conducted from 1956 to 2011, and highlights open research questions. The database revealed conflicting results following rewetting and thawing in various terrestrial ecosystems and among soil gases, ranging from large increases in fluxes to non-significant changes. Studies reporting lower gas fluxes before rewetting tended to find higher post-rewetting fluxes for CO2, N2O and NO; in addition, increases in N2O flux following thawing were greater in warmer climate regions. We discuss possible mechanisms and controls that regulate flux responses, and recommend that a high temporal resolution of flux measurements is critical to capture rapid changes in gas fluxes after these soil perturbations. Finally, we propose that future studies should investigate the interactions between biological (i.e., microbial community and gas production and physical (i.e., porosity, diffusivity, dissolution changes in soil gas fluxes, apply techniques to capture rapid changes (i.e., automated measurements, and explore synergistic experimental and modelling approaches.

  5. 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.

  6. Improvement of post-thawed sperm quality and fertility of Arian rooster by oral administration of d-aspartic acid.

    Science.gov (United States)

    Ansari, Mahdi; Zhandi, Mahdi; Kohram, Hamid; Zaghari, Mojtaba; Sadeghi, Mostafa; Sharafi, Mohsen

    2017-04-01

    This study was conducted to investigate the effect of d-Aspartic acid (D-Asp) on post-thawed sperm quality, fertility and hatchability outcomes in male broiler breeders. Twenty 55-week-old roosters were selected and equally split into four groups (n = 5 rooster/group). Different daily D-Asp doses including 0 (D-0), 100 (D-100), 200 (D-200) or 300 (D-300) mg/kg BW were capsulated and individually administered for 12 weeks to roosters in each group. Semen samples were weekly collected from 7th to 12th week of experiment. Sperm quality from 7th to 11th week was evaluated in both fresh (total and forward motility and plasma membrane functionality) and post-thawed (total and forward motility, plasma membrane functionality, apoptosis status and mitochondrial activity) conditions. Also, collected semen samples on the 12th week were frozen and artificially inseminated to evaluate fertility and hatchability. The results from fresh condition showed that total and forward motility and plasma membrane functionality were significantly higher in D-200 compared to other groups. Also, interaction effect of time and treatment was not significant for all assessed parameters in fresh condition. In post-thawed condition, D-200 showed significantly higher total and forward motility, fertility and hatchability compared to other groups. The higher value for plasma membrane functionality and mitochondrial activity was observed in D-200 compared to D-0 and D300 groups. However, the percentage of live, early apoptotic and dead spermatozoa were not significantly affected by applied treatment in the current study. No significant difference for time and treat interaction effect was observed for all assessed parameters except forward motility. In conclusion, it seems that D-Asp administration could improve fresh and post-thawed sperm quality and post-thawed sperm fertility in male broiler breeders. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. 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.

  8. Petroleum hydrocarbon biodegradation under seasonal freeze-thaw soil temperature regimes in contaminated soils from a sub-Arctic site.

    Science.gov (United States)

    Chang, Wonjae; Klemm, Sara; Beaulieu, Chantale; Hawari, Jalal; Whyte, Lyle; Ghoshal, Subhasis

    2011-02-01

    Several studies have shown that biostimulation in ex situ systems such as landfarms and biopiles can facilitate remediation of petroleum hydrocarbon contaminated soils at sub-Arctic sites during summers when temperatures are above freezing. In this study, we examine the biodegradation of semivolatile (F2: C10-C16) and nonvolatile (F3: C16-C34) petroleum hydrocarbons and microbial respiration and population dynamics at post- and presummer temperatures ranging from -5 to 14 °C. The studies were conducted in pilot-scale tanks with soils obtained from a historically contaminated sub-Arctic site in Resolution Island (RI), Canada. In aerobic, nutrient-amended, unsaturated soils, the F2 hydrocarbons decreased by 32% during the seasonal freeze-thaw phase where soils were cooled from 2 to -5 °C at a freezing rate of -0.12 °C d(-1) and then thawed from -5 to 4 °C at a thawing rate of +0.16 °C d(-1). In the unamended (control) tank, the F2 fraction only decreased by 14% during the same period. Biodegradation of individual hydrocarbon compounds in the nutrient-amended soils was also confirmed by comparing their abundance over time to that of the conserved diesel biomarker, bicyclic sesquiterpanes (BS). During this period, microbial respiration was observed, even at subzero temperatures when unfrozen liquid water was detected during the freeze-thaw period. An increase in culturable heterotrophs and 16S rDNA copy numbers was noted during the freezing phase, and the (14)C-hexadecane mineralization in soil samples obtained from the nutrient-amended tank steadily increased. Hydrocarbon degrading bacterial populations identified as Corynebacterineae- and Alkanindiges-related strains emerged during the freezing and thawing phases, respectively, indicating there were temperature-based microbial community shifts.

  9. Cryopreservation of Iberian pig spermatozoa. Comparison of different freezing extenders based on post-thaw sperm quality.

    Science.gov (United States)

    De Mercado, Eduardo; Rodríguez, Ana; Gómez, Emilio; Sanz, Elena

    2010-03-01

    The aim of this study was to evaluate the cryoprotective effect of different freezing extenders against cryopreservation injuries on Iberian boar sperm. The sperm-rich fraction was collected and pooled from six sexually mature Iberian boars, and was frozen in different extenders containing glucose, lactose or fructose as sugar source and including Orvus ES Paste only in the freezing extender-2 (Glucose; Lactose and Fructose) or in both freezing extenders (Glucose2; Lactose2 and Fructose2). During the cryopreservation process, the supernatant was removed after the centrifugation step, then was extended with freezing extender-1 for the equilibration period and with freezing extender-2 immediately before freezing. Post-thaw sperm characteristics, such as plasma membrane integrity (SYBR-14/PI), mitochondrial function (Rhodamine 123) and acrosome integrity (NAR), were monitored. Overall sperm motility and the individual kinematic parameters of motile spermatozoa (assessed by the computer-aided sperm analysis system Sperm Class Analyzer [SCA]) were recorded in the different experimental treatments. Measurements were taken at 30 and 150 min post-thaw. The state of the acrosome after thawing did not show significant differences between the freezing extenders studied. Freezing-thawing caused a significant decrease (Pextenders. Furthermore, spermatozoa frozen with Orvus ES Paste in both freezing extenders exhibited lower (Pextender. The spermatozoa frozen with the Lactose extender and with Orvus ES Paste only in the second freezing extender showed a better evolution of the motility and kinematic characteristics (Pextenders studied in the present experiment affected the quality of frozen-thawed semen in Iberian boar.

  10. Effect of different cryo-protectants on the viability of frozen/thawed semen from boars of the Piau breed.

    Science.gov (United States)

    Pinho, R O; Lima, D M A; Shiomi, H H; Siqueira, J B; Silva, H T; Lopes, P S; Guimarães, S E F; Guimarães, J D

    2014-05-01

    The objective of this study was to evaluate the effect of different cryo-protectants (glycerol, dimethylacetamide and dimethylformamide alone or combined and added to lactose-egg yolk extender) on the viability of frozen/thawed semen from the Piau breed as assessed by in vitro testing. Frozen semen samples (n=20) were used from five male swine. Five different freezing extenders, including 2% glycerol (Group 1 - G), 2% glycerol and 3% dimethylacetamide (Group 2 - GA), 2% glycerol and 3% dimethylformamide (Group 3 - GF), 5% dimethylacetamide (Group 4 - A) and 5% dimethylformamide (group 5 - F), were evaluated. To assess post-thawing sperm quality, sperm motility and morphology were evaluated. Sperm viability was determined using the hypoosmotic swelling test, supravital staining, and a fluorescent assay (carboxyfluorescein diacetate and propidium iodide). The mean total sperm motility of semen immediately after thawing was 46.2±1.3, 57.7±1.5, 53.2±2.1, 51.7±1.2, and 46.5±1.6% for groups 1-5, respectively. Groups 2 (GA) and 3 (GF) had greater motility values (P0.05). The other complementary tests (hypoosmotic swelling test and supra-vital staining) demonstrated that sperm in Groups 2 (GA), 3 (GF) and 4 (A) had the greatest viability and there were no significant differences among these three groups (P>0.05). The most effective cryo-protectant combinations likely minimized and controlled the deleterious processes that occur in the sperm cell during freezing/thawing, thus improving post-thawing sperm viability. In conclusion, the combination of amides (3%) and glycerol (2%) or dimethylacetamide (5%) alone were more efficient at cryo-protection than glycerol alone for semen freezing in the Piau swine breed. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Effect of multiple freeze-thaw cycles on the quality of instant sea cucumber: Emphatically on water status of by LF-NMR and MRI.

    Science.gov (United States)

    Tan, Mingqian; Lin, Zhuyi; Zu, Yinxue; Zhu, Beiwei; Cheng, Shasha

    2018-07-01

    Instant sea cucumber has become one popular product due to its convenience to eat, favourable taste and minimal loss of nutrients and bioactive components. However, there was rare information about the water dynamic of instant sea cucumber subjected to multiple freeze-thaw cycles. In this study, low-field nuclear magnetic resonance (LF-NMR) and magnetic resonance image (MRI) were employed to investigate the effect of freeze-thaw cycles on water status of instant sea cucumber. Four water populations corresponding to strongly bound water, weakly bound water, immobile water and free water were observed in instant sea cucumber. With the increase of freeze-thaw cycles, the transverse relaxation time of immobile and free water increased, while the peak area of free water decreased significantly. MRI enabled the visualization of water migration of instant sea cucumber during multiple freeze-thaw cycles. Multiple freeze-thaw cycles also led to significant changes of other quality properties including thawing loss, WHC, color parameters, texture and protein content, and enlarge the interspace between fiber network in microstructure. Good correlations between T 22 , A 22 , A 23 and thaw loss, WHC, L*, hardness and collagen content (0.873 ≤ r ≤ 0.958) revealed LF-NMR may be an effective real-time monitoring method of these physicochemical parameters as a non-destructive technique. Copyright © 2018 Elsevier Ltd. All rights reserved.

  12. Application of Spaceborne Scatterometer for Mapping Freeze-Thaw State in Northern Landscapes as a Measure of Ecological and Hydrological Processes

    Science.gov (United States)

    McDonald, Kyle; Kimball, John; Zimmermann, Reiner; Way, JoBea; Frolking, Steve; Running, Steve

    1999-01-01

    Landscape freeze/thaw transitions coincide with marked shifts in albedo, surface energy and mass exchange, and associated snow dynamics. Monitoring landscape freeze/thaw dynamics would improve our ability to quantify the interannual variability of boreal hydrology and river runoff/flood dynamics. The annual duration of frost-free period also bounds the period of photosynthetic activity in boreal and arctic regions thus affecting the annual carbon budget and the interannual variability of regional carbon fluxes. In this study, we use the NASA scatterometer (NSCAT) to monitor the temporal change in the radar backscatter signature across selected ecoregions of the boreal zone. We have measured vegetation tissue temperatures, soil temperature profiles, and micrometeorological parameters in situ at selected sites along a north-south transect extending across Alaska from Prudhoe Bay to the Kenai Peninsula and in Siberia near the Yenisey River. Data from these stations have been used to quantify the scatterometer's sensitivity to freeze/thaw state under a variety of terrain and landcover conditions. Analysis of the NSCAT temporal response over the 1997 spring thaw cycle shows a 3 to 5 dB change in measured backscatter that is well correlated with the landscape springtime thaw process. Having verified the instrument's capability to monitor freeze/thaw transitions, regional scale mosaicked data are applied to derive temporal series of freeze/thaw transition maps for selected circumpolar high latitude regions. These maps are applied to derive areal extent of frozen and thawed landscape and demonstrate the utility of spaceborne radar for operational monitoring of seasonal freeze-thaw dynamics and associated biophysical processes for the circumpolar high latitudes.

  13. Permafrost soil characteristics and microbial community structure across a boreal forest watershed vary over short spatial scales and dictate community responses to thaw.

    Science.gov (United States)

    Stegen, J.; Bottos, E. M.; Kennedy, D.; Romero, E. B.; Fansler, S.; Chu, R. K.; Tfaily, M.; Jansson, J.; Bernstein, H. C.; Brown, J. M.; Markillie, L. M.

    2017-12-01

    Understanding drivers of permafrost microbial community structure and function is critical for understanding permafrost microbiology and predicting ecosystem responses to thaw; however, studies describing ecological controls on these communities are lacking. We hypothesize that permafrost communities are uniquely shaped by constraints imposed by prolonged freezing, and decoupled from the selective factors that influence non-permafrost soil communities, but that pre-thaw environmental and community characteristics will be strong determinants of community structure and function post-thaw. We characterized patterns of environmental variation and microbial community composition in sixty permafrost samples spanning landscape gradients in a boreal forest watershed, and monitored community responses to thaw. Consistent with our hypothesis, we found that, proportionally, the strongest process influencing permafrost community composition was dispersal limitation (0.36), exceeding the influence of homogenous selection (0.21) and variable selection (0.16), and that deterministic selection arose primarily from energetic constraints of the permafrost environment. Our data supported a structural equation model in which organic carbon thermodynamics and organic acid content, influenced redox conditions and total selection. Post-thaw community composition was found to be driven primarily by pre-thaw community composition, indicating a strong influence of historical conditions. Together, these results suggest that community responses to thaw may be highly varied over short distances and that changes in community structure and function are likely to be drastic, as changes to system hydrology mobilize organisms and nutrients, thereby relieving the primary constraints on the system. These findings are being integrated with metabolomic and metatranscriptomic analyses to improve understanding of how pre-thaw conditions can be used to predict microbial activity post-thaw.

  14. Neonatal Phosphate Nutrition Alters <em>in em>Vivo> and <em>in em>Vitro> Satellite Cell Activity in Pigs

    Directory of Open Access Journals (Sweden)

    Chad H. Stahl

    2012-05-01

    Full Text Available Satellite cell activity is necessary for postnatal skeletal muscle growth. Severe phosphate (PO4 deficiency can alter satellite cell activity, however the role of neonatal PO4 nutrition on satellite cell biology remains obscure. Twenty-one piglets (1 day of age, 1.8 ± 0.2 kg BW were pair-fed liquid diets that were either PO4 adequate (0.9% total P, supra-adequate (1.2% total P in PO4 requirement or deficient (0.7% total P in PO4 content for 12 days. Body weight was recorded daily and blood samples collected every 6 days. At day 12, pigs were orally dosed with BrdU and 12 h later, satellite cells were isolated. Satellite cells were also cultured <em>in vitroem> for 7 days to determine if PO4 nutrition alters their ability to proceed through their myogenic lineage. Dietary PO4 deficiency resulted in reduced (<em>P> < 0.05 sera PO4 and parathyroid hormone (PTH concentrations, while supra-adequate dietary PO4 improved (<em>P> < 0.05 feed conversion efficiency as compared to the PO4 adequate group. <em>In vivoem> satellite cell proliferation was reduced (<em>P> < 0.05 among the PO4 deficient pigs, and these cells had altered <em>in vitroem> expression of markers of myogenic progression. Further work to better understand early nutritional programming of satellite cells and the potential benefits of emphasizing early PO4 nutrition for future lean growth potential is warranted.

  15. Constituents from <em>Vigna em>vexillata> and Their Anti-Inflammatory Activity

    Directory of Open Access Journals (Sweden)

    Guo-Feng Chen

    2012-08-01

    Full Text Available The seeds of <em>Vigna em>genus are important food resources and there have already been many reports regarding their bioactivities. In our preliminary bioassay, the chloroform layer of methanol extracts of<em> V. vexillata em>demonstrated significant anti-inflammatory bioactivity. Therefore, the present research is aimed to purify and identify the anti-inflammatory principles of <em>V. vexillataem>. One new sterol (1 and two new isoflavones (2,3 were reported from the natural sources for the first time and their chemical structures were determined by the spectroscopic and mass spectrometric analyses. In addition, 37 known compounds were identified by comparison of their physical and spectroscopic data with those reported in the literature. Among the isolates, daidzein (23, abscisic acid (25, and quercetin (40 displayed the most significant inhibition of superoxide anion generation and elastase release.

  16. 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

  17. Elemental composition and optical properties reveal changes in dissolved organic matter along a permafrost thaw chronosequence in a subarctic peatland

    Science.gov (United States)

    Hodgkins, Suzanne B.; Tfaily, Malak M.; Podgorski, David C.; McCalley, Carmody K.; Saleska, Scott R.; Crill, Patrick M.; Rich, Virginia I.; Chanton, Jeffrey P.; 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 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 Sphagnum-dominated bogs

  18. 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.

  19. Modified natural cycle for embryo transfer using frozen-thawed blastocysts: A satisfactory option.

    Science.gov (United States)

    Le, Quoc V; Abhari, Sina; Abuzeid, Omar M; DeAnna, Jennifer; Satti, Mohamed A; Abozaid, Tarek; Khan, Iqbal; Abuzeid, Mostafa I

    2017-06-01

    To describe pregnancy outcomes of frozen-thawed blastocysts cycles using modified natural cycle frozen embryo transfers (NC-FET) and down-regulated hormonally controlled frozen embryo transfers (HC-FET) protocols. This retrospective cohort study included all patients undergoing either modified NC-FET or down-regulated HC-FET using frozen-thawed day 5 embryos. Cycles with donor blastocysts were excluded. Four hundred twenty eight patients underwent a total of 493 FET cycles. Patients with regular menses and evidence of ovulation underwent modified NC-FET. These patients were given hCG 10,000 IU IM on the day of LH-surge. Vaginal progesterone (P4) was started two days later and blastocyst transfer was planned seven days after detecting the LH surge. Anovulatory patients and some ovulatory patients underwent down-regulated HC-FET. These patients were placed on medroxy-progesterone acetate (10mg) for 10days to bring on menses and were also given a half-dose of GnRH-agonist (GnRH-a) on the third day of medroxy-progesterone acetate. Exogenous estradiol was initiated on the third day of menses. Once serum E2 levels reached >500pg/mL and endometrial lining reached >8mm, intramuscular (IM) P4 in oil was administered. Blastocyst FET was planned 6days after initiating P4. The primary outcomes included clinical pregnancy and delivery rates. There were 197 patients in the modified NC-FET protocol and 181 in the down-regulated HC-FET protocol. Mean age (years), day-3 FSH levels (mIU/mL) and percentage of patients with male factor infertility were significantly higher and mean BMI (kg/m 2 ) was significantly lower in modified NC-FET compared to HC-FET, respectively. Analysis of the first cycle pregnancy outcomes revealed no significant differences in clinical pregnancy rate (54.3% vs. 52.5%) and delivery rate (47.2% vs. 43.6%) between modified NC-FET and HC-FET. Logistic regression analysis showed age (OR=0.939, 95% CI 0.894-0.989, p=0.011), number of blastocysts transferred (OR

  20. 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

  1. 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

  2. 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

  3. Fracture energy evolution of two concretes resistant to the action of freeze-thaw cycles

    Directory of Open Access Journals (Sweden)

    Enfedaque, A.

    2014-03-01

    Full Text Available The current standards that regulate use of structural concrete have highlighted the durability of concrete. However, how the fracture energy of concrete evolves under the action of freeze-thaw cycles is not well known. The fracture energy of two types of concrete, one with an air-entraining additive and the other with silica fume addition, is studied after four, 14 and 28 freeze-thaw cycles. The results obtained show that the concrete with an air-entraining additive was undamaged and that fracture energy grew slightly. In addition to this, they also showed that the concrete with silica fume addition suffered severe surface scaling and its fracture energy changed due to the greater fracture areas generated.La actual normativa que rige el empleo de hormigón estructural ha puesto enfásis en la durabilidad del hormigón. Sin embargo, no se conoce cómo evoluciona la energía de fractura del hormigón sometido a ciclos hielo- deshielo, lo cual es de vital importancia para asegurar la durabilidad y el correcto comportamiento mecánico de las estructuras de hormigón en entornos con heladas durante su vida útil. Se ha estudiado la evolución de la energía de fractura de un hormigón con aireante y de un hormigón con humo de sílice después de 4, 14 y 28 ciclos hielo-deshielo realizando ensayos de fractura. Los resultados muestran cómo el hormigón con aireante no sufre daño por los ciclos hielo-deshielo y cómo la energía de fractura del mismo aumenta ligeramente. El hormigón con humo de sílice se daña por los ciclos hielo-deshielo y reduce su energía de fractura al aumentar el area fracturada.

  4. 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

  5. Momentos em freios e em embraiagens

    OpenAIRE

    Mimoso, Rui Miguel Pereira

    2011-01-01

    Dissertação para obtenção do Grau de Mestre em Mestrado Integrado em Engenharia Mecânica Nesta dissertação reúnem-se os modelos de cálculo utilizados na determinação dos momentos em freios e em embraiagens. Neste trabalho consideram-se os casos de freios e embraiagens de atrito seco e atrito viscoso. Nos freios de atrito viscoso são considerados casos em que as características dos fluidos não são induzidas, e outros em que são induzidas modificações a essas mesmas características. São a...

  6. Computational thermo-hydro-mechanics for freezing and thawing multiphase geological media in the finite deformation range

    Science.gov (United States)

    Sun, W.; Na, S.

    2017-12-01

    A stabilized thermo-hydro-mechanical (THM) finite element model is introduced to investigate the freeze-thaw action of frozen porous media in the finite deformation range. By applying the mixture theory, frozen soil is idealized as a composite consisting of three phases, i.e., solid grain, unfrozen water and ice crystal. A generalized hardening rule at finite strain is adopted to replicate how the elasto-plastic responses and critical state evolve under the influence of phase transitions and heat transfer. The enhanced particle interlocking and ice strengthening during the freezing processes and the thawing-induced consolidation at the geometrical nonlinear regimes are both replicated in numerical examples. The numerical issues due to lack of two-fold inf-sup condition and ill-conditioning of the system of equations are addressed. Numerical examples for engineering applications at cold region are analyzed via the proposed model to predict the impacts of changing climate on infrastructure at cold regions.

  7. Stability Evaluation of Volcanic Slope Subjected to Rainfall and Freeze-Thaw Action Based on Field Monitoring

    Directory of Open Access Journals (Sweden)

    Shima Kawamura

    2011-01-01

    Full Text Available Rainfall-induced failures of natural and artificial slopes such as cut slopes, which are subjected to freezing and thawing, have been frequently reported in Hokkaido, Japan. In particular, many failures occur intensively from spring to summer seasons. Despite numerous field studies, explanation of their mechanical behavior based on in situ data has not yet been completely achieved due to the difficulty in grasping failure conditions. This study aims at clarifying the aspects of in-situ volcanic slopes subjected to rainfall and freeze-thaw action. The changes in soil moisture, pore pressure, deformations, and temperatures in the slope were investigated using soil moisture meters, tensiometers, thermocouple sensors, clinometers, settlement gauges, an anemovane, a snow gauge, and a rainfall gauge. The data generated from these measures indicated deformation in the slope examined mainly proceeded during the drainage process according to changes in soil moisture. Based on this data, a prediction method for failures is discussed in detail.

  8. 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

    . 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......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...... of Baltic Sea cod. Therefore, addition of trimethylamine oxide and NaCl to Baltic Sea cod fillets was evaluated and shown to protect P, phosphoreum against fro::en storage inactivation and this explained the observed differences in growth of the spoilage bacteria and trimethylamine production between thawed...

  9. Laboratory studies on the effect of freezing and thawing exposure on bentonite buffer performance: Closed-system tests

    Energy Technology Data Exchange (ETDEWEB)

    Schatz, T.; Martikainen, J. [B and Tech Oy, Helsinki (Finland)

    2010-12-15

    This report presents a set of results from laboratory studies on the effect of freezing and thawing on compacted bentonite buffer material. In order to evaluate the effect of freezing and thawing on compacted bentonite buffer performance a series of experiments were conducted using closed, constant-volume cells as follows: Pre- and post-freezing swelling pressure measurements were performed on fully saturated MX-80 and Deponit CA-N bentonite samples, at dry density values of approximately 1.6 g/cm{sup 3}, over five freeze/thaw cycles from room temperature to -18 deg C with rapid (instantaneous) temperature exposure. Pressure measurements were performed on fully saturated MX-80 bentonite samples, at dry density values of 1.470 and 1.501 g/cm{sup 3}, during a temperature run from room temperature to -10 deg C with step-change temperature exposure and back from -10 deg C to room temperature under continuous temperature change exposure at 0.1 deg C/h. Pressure measurements were performed on fully saturated MX-80 bentonite samples, encompassing a range of dry density values from 0.940 to 1.534 g/cm{sup 3}, during repeated temperature runs from room temperature to -10 deg C and back with continuous temperature change exposure at 0.1 deg C/h. Pressure measurements were performed on a fully saturated Deponit CA-N bentonite sample, at a dry density of 1.484 g/cm{sup 3}, during a temperature run from room temperature to -10 deg C and back with continuous temperature change exposure at 0.1 deg C/h. In some cases, hydraulic conductivity measurements were performed before and after freeze/thaw exposure. In general, exposure to freezing temperatures, down to an average temperature of -10 deg C, results in the development of significant internal pressures in compacted bentonite samples, which is attributed to the formation of ice. The specific test results are summarised as follows: Increases in pressure by factors of 1.5 to 2.2 were observed for MX-80 samples at dry densities

  10. Use of the TLX ultracentrifuge for the isolation of different density lipoproteins and effects of freeze/thawing of human plasma before ultracentrifugation.

    Science.gov (United States)

    Charlton-Menys, Valentine; Chobotova, Jelena; Durrington, Paul N

    2008-01-01

    Isolation of different density lipoproteins by ultracentrifugation can require lengthy centrifugation times and freeze/thawing of plasma may influence recovery. We isolated a range of lipoproteins using a preparative ultracentrifuge and the TLX micro-ultracentrifuge and determined the effect of freeze/thawing of plasma beforehand. In fresh plasma, there was no significant difference in results for small-dense low-density lipoprotein apolipoprotein B (LDL apoB) (density >1.044 g/mL) or cholesterol at density >1.006 g/mL. Freeze/thawing had no effect on closely correlated results for small-dense LDL apoB (r=0.85; pTLX micro-ultracentrifuge is a reliable alternative to the preparative ultracentrifuge and freeze/thawing has only a small effect on small-dense LDL apoB or high-density lipoprotein cholesterol.

  11. Successful application of the strategy of blastocyst biopsy, vitrification, whole genome amplification, and thawed embryo transfer for preimplantation genetic diagnosis of neurofibromatosis type 1

    Directory of Open Access Journals (Sweden)

    Yi-Lin Chen

    2011-03-01

    Conclusion: We first demonstrate successful application of blastocyst biopsy, vitrification, WGA, and thawed embryo transfer for PGD of a monogenic disease. Vitrification of blastocysts after biopsy permits sufficient time for shipment of samples and operation of molecular diagnosis.

  12. Thawed chilled Barents Sea cod fillets in modified atmosphere packaging-application of multivariate data analysis to select key parameters in good manufacturing practice

    DEFF Research Database (Denmark)

    Bøknæs, Niels; Jensen, K.N.; Guldager, H.S.

    2002-01-01

    The purpose of the present study was to select key parameters in good manufacturing practice for production of thawed chilled modified atmosphere packed (MAP) cod (Gadus morhua) fillets. The effect of frozen storage temperature (-20 and -30 C), frozen storage period (3, 6, 9 and 12 mo) and chill...... storage periods up to 21 d at 2 C were evaluated for thawed MAP Barents Sea cod fillets. Sensory, chemical, microbiological and physical quality attributes were evaluated and multivariate data analysis (principal component analysis and partial least- squares regression) applied for identification of key...... storage was low for thawed MAP Barents Sea cod and this fish raw material seemed the more appropriate for production of thawed chilled MAP products. Frozen storage inactivation of the spoilage bacteria of Photobacterium phosphorcum was modest in Barnets Sea cod, possibly due to high trimethylamine oxide...

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

    DEFF Research Database (Denmark)

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

    2017-01-01

    Background and aim: Nutrient distribution and carbon fluxes upon spring thaw are compared in mesocosms from high arctic and subarctic ecosystems dominated by Cassiope tetragona or Salix hastata/Salix arctica, in order to evaluate the possibility of plant and microbial utilization of an organic...... compound in thawing permafrost and surface soil. Methods: Double labeled glycine (13C15N) was added to soil columns with vegetation and to permafrost. During thaw conditions ecosystem respiration 13C was measured and 13C and 15N distribution in the ecosystem pools was quantified one day and one month after...... glycine addition. Results: Near-surface soil microbes were more efficient in the uptake of intact glycine immediately upon thaw than plants. After one month plants had gained more 15N whereas microbes seemed to lose 15N originating from glycine. We observed a time lag in glycine degradation upon...

  14. 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-...

  15. 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...

  16. Cryopreservation of boar semen. III: Ultrastructure of boar spermatozoa frozen ultra-rapidly at various stages of conventional freezing and thawing.

    Science.gov (United States)

    Bwanga, C O; Ekwall, H; Rodriguez-Martinez, H

    1991-01-01

    Ejaculated boar spermatozoa subjected to a conventional freezing and thawing process, were ultra-rapidly fixed, freeze-substituted and examined by electron microscopy to monitor the presence of real or potential intracellular ice and the degree of cell protection attained with the different extenders used during the process. Numerous ice crystal marks representing the degree of hydration of the cells were located in the perinuclear space of those spermatozoa not in proper contact with the extender containing glycerol (i.e. prior to freezing). The spermatozoa which were in proper contact with the extenders presented a high degree of preservation of the acrosomes, plasma membranes as well as the nuclear envelopes. No ice marks were detected in acrosomes before thawing, indicating that the conventional assayed cryopreservation method provided a good protection against cryoinjury. The presence of acrosomal changes (internal vesiculization, hydration and swelling) in thawed samples however, raises serious questions about the thawing procedure employed.

  17. The Effects of Permafrost Thaw on Organic Matter Quality and Availability Along a Hill Slope in Northeastern Siberia

    Science.gov (United States)

    Connolly, C. T.; Spawn, S.; Ludwig, S.; Schade, J. D.; Natali, S.

    2014-12-01

    Climate warming and permafrost thaw in northeastern Siberia are expected to change the quantity and quality of organic matter (OM) transported through watersheds, releasing previously frozen carbon (C) to biologically available pool. Hill slopes have shown to influence the distribution of OM, resulting in a downhill accumulation of available C and nutrients relative to uphill. Here we examine how future permafrost thaw will change OM quality and availability along a hill slope in a larch-dominated watershed. We collected soils from the thawed organic and mineral layers, and 1m deep permafrost cores for dissolved organic C (DOC) and total dissolved N (TDN), C composition from measures of colored dissolved organic matter (CDOM), DOC lability from biodegradable DOC (BDOC) incubations, C and nutrient availability from extracellular-enzyme assays (EEA's), and microbial respiration from aerobic soil incubations. Here we show that organic soils (O), in comparison to mineral soils (M) and permafrost (P) are the most abundant source of C (avg O DOC: 51.6mg/L), exhibiting low molecular complexity (avg O SUVA254: 4.05) and high quality. Evidence suggests permafrost OM may be an equally abundant, and more labile source of C than mineral soils (highest P DOC: 16.1 mg/L, lowest P SUVA254: 6.32; median M DOC: 18.5 mg/L, median M SUVA254: 24.0). Furthermore, we demonstrate that there may be a positive relationship in the rate of C mineralization and distance downhill, showing 15-30% greater CO2 production/gC downhill relative to uphill. Evidence also supports a similar relationship in permafrost DOC content and molecular complexity, showing more DOC of a lower complexity further downhill. This indicates DOC transport may have been occurring through the active layer and downhill during ice-rich permafrost formation, and may supply a labile source of carbon to lowland areas and adjacent stream networks upon thaw.

  18. 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.

  19. In Vivo Perturbation of Membrane-Associated Calcium by Freeze-Thaw Stress in Onion Bulb Cells 1

    Science.gov (United States)

    Arora, Rajeev; Palta, Jiwan P.

    1988-01-01

    Incipient freeze-thaw stress in onion bulb scale tissue is known to cause enhanced efflux of K+, along with small but significant loss of cellular Ca2+. During the post-thaw period, irreversibly injured cells undergo a cytological aberration, namely, `protoplasmic swelling.' This cellular symptom is thought to be caused by replacement of Ca2+ from membrane by extracellular K+ and subsequent perturbation of K+ transport properties of plasma membrane. In the present study, onion (Allium cepa L. cv Sweet Sandwich) bulbs were slowly frozen to either −8.5°C or −11.5°C and thawed over ice. Inner epidermal peels from bulb scales were treated with fluorescein diacetate for assessing viability. In these cells, membrane-associated calcium was determined using chlorotetracycline fluorescence microscopy combined with image analysis. Increased freezing stress and tissue infiltration (visual water-soaking) were paralleled by increased ion leakage. Freezing injury (−11.5°C; irreversible) caused a specific and substantial loss of membrane-associated Ca2+ compared to control. Loss of membrane-associated Ca2+ caused by moderate stress (−8.5°C; reversible) was much less relative to −11.5°C treatment. Ion efflux and Ca2+-chlorotetracycline fluorescence showed a negative relationship. Extracellular KCl treatment simulated freeze-thaw stress by causing a similar loss of membrane-associated calcium. This loss was dramatically reduced by presence of extracellular CaCl2. Our results suggest that the loss of membrane-associated Ca2+, in part, plays a role in initiation and progression of freezing injury. Images Fig. 1 Fig. 2 PMID:16666196

  20. Enriching the captive elephant population genetic pool through artificial insemination with frozen-thawed semen collected in the wild.

    Science.gov (United States)

    Hildebrandt, T B; Hermes, R; Saragusty, J; Potier, R; Schwammer, H M; Balfanz, F; Vielgrader, H; Baker, B; Bartels, P; Göritz, F

    2012-10-01

    The first successful AI in an elephant was reported in 1998, using fresh semen. Since then almost 40 calves have been produced through AI in both Asian and African elephants worldwide. Following these successes, with the objective of enriching the captive population with genetic material from the wild, we evaluated the possibility of using frozen-thawed semen collected from wild bulls for AI in captivity. Semen, collected from a 36-yr-old wild African savanna elephant (Loxodonta africana) in South Africa was frozen using the directional freezing technique. This frozen-thawed semen was used for four inseminations over two consecutive days, two before and two after ovulation, in a 26-yr-old female African savanna elephant in Austria. Insemination dose of 1200 × 10(6) cells per AI with 61% motility resulted in pregnancy, which was confirmed through ultrasound examination 75, 110 and 141 days after the AI procedure. This represents the first successful AI using wild bull frozen-thawed semen in elephants. 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, as was done in this study, between wild and captive populations, without the need to transport stressed or potentially disease-carrying animals or to remove animals from the wild. 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 genetic diversity management and phenotype selection in these endangered mammals. Copyright © 2012 Elsevier Inc. All rights reserved.

  1. Cavitation and water fluxes driven by ice water potential in Juglans regia during freeze-thaw cycles.

    Science.gov (United States)

    Charra-Vaskou, Katline; Badel, Eric; Charrier, Guillaume; Ponomarenko, Alexandre; Bonhomme, Marc; Foucat, Loïc; Mayr, Stefan; Améglio, Thierry

    2016-02-01

    Freeze-thaw cycles induce major hydraulic changes due to liquid-to-ice transition within tree stems. The very low water potential at the ice-liquid interface is crucial as it may cause lysis of living cells as well as water fluxes and embolism in sap conduits, which impacts whole tree-water relations. We investigated water fluxes induced by ice formation during freeze-thaw cycles in Juglans regia L. stems using four non-invasive and complementary approaches: a microdendrometer, magnetic resonance imaging, X-ray microtomography, and ultrasonic acoustic emissions analysis. When the temperature dropped, ice nucleation occurred, probably in the cambium or pith areas, inducing high water potential gradients within the stem. The water was therefore redistributed within the stem toward the ice front. We could thus observe dehydration of the bark's living cells leading to drastic shrinkage of this tissue, as well as high tension within wood conduits reaching the cavitation threshold in sap vessels. Ultrasonic emissions, which were strictly emitted only during freezing, indicated cavitation events (i.e. bubble formation) following ice formation in the xylem sap. However, embolism formation (i.e. bubble expansion) in stems was observed only on thawing via X-ray microtomography for the first time on the same sample. Ultrasonic emissions were detected during freezing and were not directly related to embolism formation. These results provide new insights into the complex process and dynamics of water movements and ice formation during freeze-thaw cycles in tree stems. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  2. Influence of cryoprotectants glycerol and amides, combined with antioxidants on quality of frozen-thawed boar sperm.

    Science.gov (United States)

    Buranaamnuay, K; Grossfeld, R; Struckmann, C; Rath, D

    2011-08-01

    The present study was undertaken to examine whether the cooling and freezing extenders containing a mixture of antioxidants (AOs) catalase, Na-pyruvate and mercaptoethanol and one of three types of cryoprotectants (CPs) would be able to improve the quality of frozen-thawed boar sperm. The collected semen, only the sperm-rich fraction, was diluted 1:1 with Androhep plus™ extender, stored at 15°C for 2 h and centrifuged. The centrifuged sperm pellet was re-suspended in lactose-egg yolk extender and divided into four groups for mixing with freezing extenders containing different kinds of CPs at 5°C: (I) glycerol (GLY) as control; (II) GLY with AOs; (III) dimethyl formamide (DMF) with AOs and (IV) dimethyl acetamide (DMA) with AOs. Processed sperm were packaged in 0.25-mL straws and frozen using a controlled rate freezer. After thawing, the diluted thawed sperm were incubated at 38°C for 10 min and was assessed for motility by CASA, membrane/acrosome integrity by FITC-PNA/PI and DNA integrity (DFI) by SCSA. All sperm parameters evaluated, except DFI, were negatively affected (P0.05). There was no difference in DFI among the studied groups (P>0.05). In conclusion, based on the present results, addition of AOs to cooling and freezing extenders and/or replacement of GLY with DMF or DMA could not improve quality of frozen-thawed boar sperm. Copyright © 2011 Elsevier B.V. All rights reserved.

  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. Effects of Diatomite and SBS on Freeze-Thaw Resistance of Crumb Rubber Modified Asphalt Mixture

    Directory of Open Access Journals (Sweden)

    Haibin Wei

    2017-01-01

    Full Text Available Asphalt mixture is susceptible to moisture damage under the effect of freeze-thaw (F-T cycles. In this paper, crumb rubber (CR was used to modify stone mastic asphalt (SMA and the effects of diatomite and styrene butadiene styrene (SBS on antifreezing performances of crumb rubber modified SMA (CRSMA were investigated. Regression analysis and modified grey model (MGM were used to construct the prediction models for properties of modified mixtures. CRSMA, CR and diatomite modified SMA (CRDSMA, and CR and SBS modified SMA (CRSSMA were prepared in laboratory, respectively. Process of F-T cycles was designed. Air void, indirect tensile strength (ITS, and indirect tensile stiffness modulus (ITSM were measured to evaluate the antifreezing performances of CRSMA, CRDSMA, and CRSSMA. Results indicate that air voids increase with the increasing of F-T cycles. ITS and ITSM all decrease with the increasing of F-T cycles. The addition of diatomite and SBS can reduce the air void and improve the ITS and ITSM of CRSMA. CRSSMA presents the lowest air void, highest tensile strength, and largest stiffness modulus, which reveals that CRSSMA has the best F-T resistance among three different kinds of mixtures. Moreover, MGM (1, 2 models present more favorable accuracy in prediction of air void and ITS compared with regression ones.

  5. Effects of the ionizing radiations, freezing and thawing duration on chicken liver cells quality

    International Nuclear Information System (INIS)

    Duarte, R.C.; Araujo, M.M.; Salum, D.C.; Marchioni, E.; Villavicencio, A.L.C.H.

    2009-01-01

    All food storage processes modify the food. Irradiation reduces and could stop cell division, avoid infestation, reduce contamination and delay food decomposition. The cold chain is a succession of steps which maintains the food at low temperature. Defrosted food shall never be frozen again, the best way being to consume it quickly then avoiding multiplication and acceleration of microbial growth, which causes decay and nutrients damage. The Comet Assay indicates DNA damage and can then be used to control the overall quality of the food and in a certain extent to evaluate the damage caused by irradiation and storage on liver chicken cells. In this work, different thawing temperatures and radiation doses were checked to establish a 'DNA damage index' by using the Comet Assay. Samples were irradiated in a 60 Co irradiator with 1.5, 3.0 and 4.5 kGy radiation doses. Our results showed that no intact cells were detected in frozen samples: however, irradiated liver samples in natura showed some intact cells depending on the applied radiation doses.

  6. Permafrost thaw and intense thermokarst activity decreases abundance of stream benthic macroinvertebrates.

    Science.gov (United States)

    Chin, Krista S; Lento, Jennifer; Culp, Joseph M; Lacelle, Denis; Kokelj, Steven V

    2016-08-01

    Intensification of permafrost thaw has increased the frequency and magnitude of large permafrost slope disturbances (mega slumps) in glaciated terrain of northwestern Canada. Individual thermokarst disturbances up to 40 ha in area have made large volumes of previously frozen sediments available for leaching and transport to adjacent streams, significantly increasing sediment and solute loads in these systems. To test the effects of this climate-sensitive disturbance regime on the ecology of Arctic streams, we explored the relationship between physical and chemical variables and benthic macroinvertebrate communities in disturbed and undisturbed stream reaches in the Peel Plateau, Northwest Territories, Canada. Highly disturbed and undisturbed stream reaches differed with respect to taxonomic composition and invertebrate abundance. Minimally disturbed reaches were not differentiated by these variables but rather were distributed along a disturbance gradient between highly disturbed and undisturbed sites. In particular, there was evidence of a strong negative relationship between macroinvertebrate abundance and total suspended solids, and a positive relationship between abundance and the distance from the disturbance. Increases in both sediments and nutrients appear to be the proximate cause of community differences in highly disturbed streams. Declines in macroinvertebrate abundance in response to slump activity have implications for the food webs of these systems, potentially leading to negative impacts on higher trophic levels, such as fish. Furthermore, the disturbance impacts on stream health can be expected to intensify as climate change increases the frequency and magnitude of thermokarst. © 2016 John Wiley & Sons Ltd.

  7. Effects of salinity on physicochemical properties of Alaska pollock surimi after repeated freeze-thaw cycles.

    Science.gov (United States)

    Kang, E J; Hunt, A L; Park, J W

    2008-06-01

    The effects of residual salt in surimi on physicochemical properties as affected by various freeze and thaw (FT) cycles were examined. Fresh Alaska pollock surimi was mixed with 4.0% sugar and 5.0% sorbitol, along with 8 combinations of salt (0.4%, 0.6%, 0.8%, and 1.0% NaCl) and sodium polyphosphate (0.25% and 0.5%), vacuum-packed, and stored at -18 degrees C until used. FT cycles (0, 6, and 9) were used to mimic long-term frozen storage. At the time of gel preparation, each treatment was appropriately adjusted to maintain 2% salt and 78% moisture. The pH decreased as residual salt increased during frozen storage. Salt extractable protein (SEP) decreased (P residual salt and phosphate concentration during frozen storage, whiteness value (L*- 3b*) decreased (P salt/0.5% phosphate and 0.6% salt/0.25% phosphate. Water retention ability (WRA) and texture significantly (P salt content (0.8% and 1.0%) after 9 FT cycles, indicating higher residual salt concentration can shorten the shelf life of frozen surimi. Our study revealed lower residual salt concentration and higher phosphate concentration are likely to extend the shelf life of frozen surimi.

  8. 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.

  9. Live births after polar body biopsy and frozen-thawed cleavage stage embryo transfer: case report.

    Science.gov (United States)

    Guimarães, Fernando; Roque, Matheus; Valle, Marcello; Kostolias, Alessandra; Azevedo, Rodrigo A de; Martinhago, Ciro D; Sampaio, Marcos; Geber, Selmo

    2016-12-01

    Pre-implantation genetic diagnosis (PGD) or screening (PGS) technology, has emerged and developed in the past few years, benefiting couples as it allows the selection and transfer of healthy embryos during IVF treatments. These techniques can be performed in oocytes (polar-body biopsy) or embryos (blastomere or trophectoderm biopsy). In this case report, we describe the first two live births to be published in Brazil after a polar-body (PB) biopsy. In case 1, a 42-year-old was submitted to PB biopsy with PGS due to advanced maternal age and poor ovarian reserve. Five MII oocytes underwent first and second polar body biopsy and four cleavage embryos were cryopreserved. The PGS analysis resulted in two euploid embryos (next generation sequence). A frozen-thawed embryo transfer (FET) was performed after endometrial priming and a healthy baby was delivered after a cesarean section (37 weeks, female, 3390g, 47.5 cm). In case 2, a 40-year old patient with balanced translocation and poor ovarian response was submitted to PB biopsy. Two MII oocytes underwent first and second polar body biopsy and two embryos were cryopreserved in cleavage stage. The analysis resulted in one euploid embryo that was transferred after endometrial priming. A preterm healthy baby (34 weeks, female, 2100g, 40 cm) was delivered via cesarean section. In conclusion, although the blastocyst biopsy is the norm when performing PGS/PGD during IVF treatments, other alternatives (as PB biopsy) should be considered in some specific situations.

  10. In vitro fertilization of in vitro matured canine oocytes using frozen-thawed dog semen.

    Science.gov (United States)

    De los Reyes, M; Carrion, R; Barros, C

    2006-10-01

    Experiments were conducted to evaluate in vitro fertilization (IVF) of in vitro matured (IVM) bitch oocytes using dog spermatozoa frozen in three different extenders. Sperm-rich fraction from eight ejaculates of five dogs was frozen in each one of three egg yolk Tris extenders with additional: (A) 1.4 g citric acid and 0.8 g glucose; (B) 0.7 g citric acid and 3.5 g glucose; or (C) 1.4 g citric acid and 0.8 g fructose (all with 5% glycerol in 100 mL milliQ water). Thawed sperm were co-incubated with IVM bitch oocytes for 6 h. Oocytes were fixed and evaluated under an epifluorescence microscope; penetrated oocytes were defined as those having sperm heads in the perivitelline space or in the oocyte cytoplasm. Higher penetration rates (P < 0.05) were obtained in oocytes cultured with spermatozoa frozen in extenders B and C than those frozen in extender A (33.1, 34.2 and 26.4%, respectively).

  11. Effects of the ionizing radiations, freezing and thawing duration on chicken liver cells quality

    Energy Technology Data Exchange (ETDEWEB)

    Duarte, R.C. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Av. Professor Lineu Prestes 2242 Zip code, 05508-000 Cidade Universitaria Sao Paulo, SP-Brazil (Brazil)], E-mail: renatocduarte@yahoo.com.br; Araujo, M.M.; Salum, D.C. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Av. Professor Lineu Prestes 2242 Zip code, 05508-000 Cidade Universitaria Sao Paulo, SP-Brazil (Brazil); Marchioni, E. [IPHC-UMR 7178-Faculte de Pharmacie, 74 route du Rhin, 67400 Illkirch (France); Villavicencio, A.L.C.H. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Av. Professor Lineu Prestes 2242 Zip code, 05508-000 Cidade Universitaria Sao Paulo, SP-Brazil (Brazil)], E-mail: villavic@ipen.br

    2009-07-15

    All food storage processes modify the food. Irradiation reduces and could stop cell division, avoid infestation, reduce contamination and delay food decomposition. The cold chain is a succession of steps which maintains the food at low temperature. Defrosted food shall never be frozen again, the best way being to consume it quickly then avoiding multiplication and acceleration of microbial growth, which causes decay and nutrients damage. The Comet Assay indicates DNA damage and can then be used to control the overall quality of the food and in a certain extent to evaluate the damage caused by irradiation and storage on liver chicken cells. In this work, different thawing temperatures and radiation doses were checked to establish a 'DNA damage index' by using the Comet Assay. Samples were irradiated in a {sup 60}Co irradiator with 1.5, 3.0 and 4.5 kGy radiation doses. Our results showed that no intact cells were detected in frozen samples: however, irradiated liver samples in natura showed some intact cells depending on the applied radiation doses.

  12. 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.

  13. Effects of different extenders on DNA integrity of boar spermatozoa following freezing-thawing.

    Science.gov (United States)

    Hu, Jian-hong; Li, Qing-wang; Jiang, Zhong-liang; Li, Wen-ye

    2008-12-01

    The sperm-rich fraction, collected from eight mature Yorkshire boars, was frozen in an extender containing 9% LDL (w/v), 100mM trehalose, or 20% yolk (v/v), respectively. Sperm DNA integrity was assessed using the single-cell gel electrophoresis (SCGE). Other sperm quality characteristics such as motility, acrosome and membrane integrity were also monitored. The results showed that freezing-thawing caused an increase in sperm DNA fragmentation, and extender containing 9% LDL could significantly protect sperm DNA integrity (Pextender containing 100mM trehalose and 20% yolk (v/v). No significant difference in damaged DNA was detected between frozen and unfrozen semen samples for extender of 9% LDL and 100mM trehalose, but cryopreservation could increase the degree of DNA damage (Pboar sperm DNA damage and protecting DNA integrity. It can be suggested that evaluation of sperm DNA integrity, coupled with correlative and basic characteristics such as motility, acrosome integrity and membrane integrity, may aid in determining the quality of frozen boar semen.

  14. Effects of alginate on frozen-thawed boar spermatozoa quality, lipid peroxidation and antioxidant enzymes activities.

    Science.gov (United States)

    Hu, Jinghua; Geng, Guoxia; Li, Qingwang; Sun, Xiuzhu; Cao, Hualin; Liu, Yawei

    2014-06-30

    Although alginate was reported to play an important role as free radical scavengers in vitro and could be used as sources of natural antioxidants, there was no study about the cryoprotective effects of alginate on boar spermatozoa freezing. The objective of this research was to evaluate the effects of different concentrations of alginate added to the freezing extenders on boar spermatozoa motility, plasma membrane integrity, acrosomal integrity, mitochondrial activities, lipid peroxidation and antioxidative enzymes activities (SOD and GSH-Px) after thawing. Alginate was added to the TCG extender to yield six different final concentrations: 0, 0.2, 0.4, 0.6, 0.8, and 1.0mg/mL. The semen extender supplemented with various doses of alginate increased (Pboar spermatozoa acrosomal integrity at concentrations of 0.6, 0.8, 1.0mg/mL, compared with that of the control (Pextenders with the presence of alginate led to higher SOD and GSH-Px activities and lower MDA levels, in comparison to the control (Pboar spermatozoa motility, functional integrity and antioxidative capacity at appropriate concentrations. Therefore alginate could be employed as an effective cryoprotectant in boar spermatozoa cryopreservation. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. 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.

  16. 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.

  17. 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.

  18. [Soil hydrolase characteristics in late soil-thawing period in subalpine/alpine forests of west Sichuan].

    Science.gov (United States)

    Tan, Bo; Wu, Fu-Zhong; Yang, Wan-Qin; Yu, Sheng; Yang, Yu-Lian; Wang, Ao

    2011-05-01

    Late soil-thawing period is a critical stage connecting winter and growth season. The significant temperature fluctuation at this stage might have strong effects on soil ecological processes. In order to understand the soil biochemical processes at this stage in the subalpine/alpine forests of west Sichuan, soil samples were collected from the representative forests including primary fir forest, fir and birch mixed forest, and secondary fir forest in March 5-April 25, 2009, with the activities of soil invertase, urease, and phosphatase (neutral, acid and alkaline phosphatases) measured. In soil frozen period, the activities of the three enzymes in test forests still kept relatively higher. With the increase of soil temperature, the activities of hydrolases at the early stage of soil-thawing decreased rapidly after a sharp increase, except for neutral phosphatease. Thereafter, there was an increase in the activities of urease and phosphatase. Relative to soil mineral layer, soil organic layer had higher hydrolase activity in late soil-thawing period, and showed more obvious responses to the variation of soil temperature.

  19. 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.

  20. Stem water transport and freeze-thaw xylem embolism in conifers and angiosperms in a Tasmanian treeline heath.

    Science.gov (United States)

    Feild, Taylor S; Brodribb, Tim

    2001-05-01

    The effect of freezing on stem xylem hydraulic conductivity and leaf chlorophyll a fluorescence was measured in 12 tree and shrub species from a treeline heath in Tasmania, Australia. Reduction in stem hydraulic conductivity after a single freeze-thaw cycle was minimal in conifers and the vessel-less angiosperm species Tasmannia lanceolata (Winteraceae), whereas mean loss of conductivity in vessel-forming angiosperms fell in the range 17-83%. A positive linear relationship was observed between percentage loss of hydraulic conductivity by freeze-thaw and the average conduit diameter across all 12 species. This supports the hypothesis that large-diameter vascular conduits have a greater likelihood of freeze-thaw cavitation because larger bubbles are produced, which are more likely to expand under tension. Leaf frost tolerances, as measured by a 50% loss of maximum PSII quantum yield, varied from -6 to -13°C, indicating that these species were more frost-sensitive than plants from northern hemisphere temperate forest and treeline communities. There was no evidence of a relationship between frost tolerance of leaves and the resilience of stem water transport to freezing, suggesting that low temperature survival and the resistance of stem water transport to freezing are independently evolving traits. The results of this study bear on the ecological importance of stem freezing in the southern hemisphere treeline zones.

  1. 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.

  2. Alpha-ketoglutarate enhances freeze-thaw tolerance and prevents carbohydrate-induced cell death of the yeast Saccharomyces cerevisiae.

    Science.gov (United States)

    Bayliak, Maria M; Hrynkiv, Olha V; Knyhynytska, Roksolana V; Lushchak, Volodymyr I

    2018-01-01

    Stress resistance and fermentative capability are important quality characteristics of baker's yeast. In the present study, we examined protective effects of exogenous alpha-ketoglutarate (AKG), an intermediate of the tricarboxylic acid cycle and amino acid metabolism, against freeze-thaw and carbohydrate-induced stresses in the yeast Saccharomyces cerevisiae. Growth on AKG-supplemented medium prevented a loss of viability and improved fermentative capacity of yeast cells after freeze-thaw treatment. The cells grown in the presence of AKG had higher levels of amino acids (e.g., proline), higher metabolic activity and total antioxidant capacity, and higher activities of catalase, NADP-dependent glutamate dehydrogenase and glutamine synthase compared to control ones. Both synthesis of amino acids and enhancement of antioxidant system capacity could be involved in AKG-improved freeze-thaw tolerance in S. cerevisiae. Cell viability dramatically decreased under incubation of stationary-phase yeast cells in 2% glucose or fructose solutions (in the absence of the other nutrients) as compared with incubation in distilled water or in 10 mM AKG solution. The decrease in cell viability was accompanied by acidification of the medium, and decrease in cellular respiration, aconitase activity, and levels of total protein and free amino acids. The supplementation with 10 mM AKG effectively prevented carbohydrate-induced yeast death. Protective mechanisms of AKG could be associated with the intensification of respiration and prevention of decreasing protein level as well as with direct antioxidant AKG action.

  3. 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)

  4. 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.

  5. Change in behavior of uniaxial compression due to degradation of salt water and freezing and thawing for rock

    International Nuclear Information System (INIS)

    Yamamoto, Kiyohito; Kobayashi, Akira; Aoyama, Shigeyasu

    2007-01-01

    To investigate the effect of the degradation on the mechanical behavior, the degraded rock samples were prepared to the uniaxial compression test. The degradation methods are divided into two types. One type is submerged in the 10% saline water (10%NaCl) for 90 days, and another one is freezing and thawing for 240 cycles. The degraded Smaland-granites were preserved in saline water. Kurihashi-granodiorite, Tage-tuff and Funyu-tuff were imposed on freezing and thawing test to make degraded state. The damage parameters were identified from the stress-strain relation obtained from the uniaxial compression tests. The damage parameters are K υ , n υ , K d , n d and B 0 . K υ and n υ are related to expansive strain. K d , n d and B 0 are subject to behavior of Young's modulus. By investigating the change in the damage parameters of the degraded rock, the effect of the degradation was tried to infer. As the results, it was inferred using the damage parameters that the Smaland-granite becomes more expansive material and the damage occurs earlier due to saline water degradation. Moreover, it was considered that the Kurihashi-granodiorite and Tage-tuff become more expansive and the axial strain at the failure decreases by freezing and thawing degradation, however the axial strain of the Funyu-tuff at the failure becomes large. It was found the proposed damage parameters can be good index for volumetric strain behavior after degradation. (author)

  6. Singleton Pregnancy Outcomes after In Vitro Fertilization with Fresh or Frozen-Thawed Embryo Transfer and Incidence of Placenta Praevia

    Directory of Open Access Journals (Sweden)

    Sara Korosec

    2014-01-01

    Full Text Available The aim of the study was to compare the single pregnancy and neonate outcome after fresh and frozen-thawed embryo transfer in the in vitro fertilization programme (IVF. The study focused on clinical and laboratory factors affecting the abnormal placentation, especially placenta praevia, in patients conceiving in the IVF programme. The results confirm that neonates born after frozen-thawed embryo transfer had significantly higher mean birth weight than after fresh embryo transfer (ET. Moreover, the birth weight distribution in singletons was found to shift towards “large for gestation” (LGA after frozen-thawed ET. On the other hand, the pregnancies after fresh ET were characterized by a higher incidence of placenta praevia and 3rd trimester bleeding. Placenta praevia was more common in IVF patients with fresh ET in a stimulated cycle than in patients with ET in a spontaneous cycle. It occurred more frequently in patients with transfer of 2 embryos. From this point of view, single ET and ET in a spontaneous cycle should be encouraged in good prognosis patients in the future with more than two good quality embryos developed. An important issue arose of how the ovarian hormonal stimulation relates to abnormal placentation and if the serum hormone levels interfere with in the IVF treatment results.

  7. A Study on Accelerated Corrosion Test by Combined Deteriorating Action of Salt Damage and Freeze-Thaw

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sang-Soon; So, Byung-Tak [Sangmyung University, Cheonan (Korea, Republic of)

    2016-01-15

    In this study, the accelerated corrosion test by combined deteriorating action of salt damage and freeze-thaw was investigated. freeze-thaw cycle is one method for corrosion testing; corrosion initiation time was measured in four types of concrete samples, i.e., two samples mixed with fly ash (FA) and blast furnace slag (BS), and the other two samples having two water/cement ratio (W/C = 0.6, 0.35) without admixture (OPC60 and OPC35). The corrosion of rebar embedded in concrete occurred most quickly at the 30th freeze-thaw cycle. Moreover, a corrosion monitoring method with a half-cell potential measurement and relative dynamic elastic modulus derived from resonant frequency measures was conducted simultaneously. The results indicated that the corrosion of rebar occurred when the relative dynamic elastic modulus was less than 60%. Therefore, dynamic elastic modulus can be used to detect corrosion of steel bar. The results of the accelerated corrosion test exhibited significant difference according to corrosion periods combined with each test condition. Consequently, the OPC60 showed the lowest corrosion resistance among the samples.

  8. 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.

  9. The detection of Giardia muris and Giardia lamblia cysts by immunofluorescence in animal tissues and fecal samples subjected to cycles of freezing and thawing.

    Science.gov (United States)

    Erlandsen, S L; Sherlock, L A; Bemrick, W J

    1990-04-01

    The effects of freezing and thawing on the detection of selected Giardia spp. cysts were investigated using immunofluorescence, bright field microscopy, and low voltage scanning electron microscopy (SEM). Giardia muris cysts were obtained from either animal carcasses, fecal pellets, or isolated cyst preparations, whereas Giardia lamblia cysts were isolated from fecal samples. These samples were stained using an immunofluorescence technique after 1-3 freezing (-16 C) and thawing (20 C) cycles. Cysts were detected successfully by immunofluorescence in all samples. However, in those samples subjected to freeze-thawing, the cyst walls often became distorted and then were not detectable by bright field microscopy. Low voltage SEM demonstrated that the filaments in the distorted cyst wall underwent rearrangements of interfilament spacing. Quantitation of cyst recovery after freezing and thawing demonstrated that a substantial loss occurred after 1 cycle of alternating temperature when low concentrations of cysts were used, but not with high concentrations of cysts. Cyst recovery, after 3 freezing and thawing cycles, was dramatically lowered irrespective of the initial cyst concentration. These results demonstrated that immunofluorescence was an effective technique for the detection of Giardia spp. cysts in frozen samples and would suggest that freezing and thawing of fecal samples could prevent the detection of cysts when only bright field microscopy was employed.

  10. Supplementation of different concentrations of Orvus Es Paste (OEP) to ostrich egg yolk lipoprotein extender improves post-thaw boar semen quality.

    Science.gov (United States)

    Fraser, L; Jasiewicz, E; Kordan, W

    2014-01-01

    This study aimed to compare post-thaw quality of boar semen following freezing in an ostrich egg yolk lipoprotein (LPFo) extender supplemented with 0%, 0.25% and 0.50% Orvus Es Paste (OEP). Sperm assessments included total motility (TMOT), mitochondrial function (MF), plasma membrane integrity (PMI) and acrosome integrity (normal apical ridge, NAR). Considerable variations among boars and OEP treatments had a significant effect (P semen samples frozen in the absence of OEP. By contrast, lactose-LPFo-glycerol extender supplemented with either 0.25% OEP or 0.50% OEP markedly enhanced post-thaw sperm characteristics. In all boars, there were no marked differences in post-thaw sperm TMOT between the freezing extenders supplemented with 0.25% and 0.50% OEP. However, a decline in the percentage of post-thaw motile spermatozoa was more pronounced in the extender supplemented with 0.50% OEP following a 120-min incubation period. Furthermore, the proportions of frozen-thawed spermatozoa with MF, PMI and NAR acrosomes varied significantly among the boars in the OEP-supplemented extenders. The findings of this study indicate that different OEP concentrations, in the presence of ostrich egg yolk lipoproteins, could have varying effects on post-thaw sperm survival.

  11. Dermatoses em renais cronicos em terapia dialitica

    Directory of Open Access Journals (Sweden)

    Luis Alberto Batista Peres

    2014-03-01

    Full Text Available Objetivo: As desordens cutâneas e das mucosas são comuns em pacientes em hemodiálise a longo prazo. A diálise prolonga a expectativa de vida, dando tempo para a manifestação destas anormalidades. Os objetivos deste estudo foram avaliar a prevalência de problemas dermatológicos em pacientes com doença renal crônica (DRC em hemodiálise. Métodos: Cento e quarenta e cinco pacientes com doença renal crônica em hemodiálise foram estudados. Todos os pacientes foram completamente analisados para as alterações cutâneas, de cabelos, mucosas e unhas por um único examinador e foram coletados dados de exames laboratoriais. Os dados foram armazenados em um banco de dados do Microsolft Excel e analisados por estatística descritiva. As variáveis contínuas foram comparadas pelo teste t de Student e as variáveis categóricas utilizando o teste do qui-quadrado ou o teste Exato de Fischer, conforme adequado. Resultados: O estudo incluiu 145 pacientes, com idade média de 53,6 ± 14,7 anos, predominantemente do sexo masculino (64,1% e caucasianos (90,0%. O tempo médio de diálise foi de 43,3 ± 42,3 meses. As principais doenças subjacentes foram: hipertensão arterial em 33,8%, diabetes mellitus em 29,6% e glomerulonefrite crônica em 13,1%. As principais manifestações dermatológicas observadas foram: xerose em 109 (75,2%, equimose em 87 (60,0%, prurido em 78 (53,8% e lentigo em 33 (22,8% pacientes. Conclusão: O nosso estudo mostrou a presença de mais do que uma dermatose por paciente. As alterações cutâneas são frequentes em pacientes em diálise. Mais estudos são necessários para melhor caracterização e manejo destas dermatoses.

  12. 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

  13. 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

  14. 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

  15. 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

  16. Soy lecithin interferes with mitochondrial function in frozen-thawed ram spermatozoa.

    Science.gov (United States)

    Del Valle, I; Gómez-Durán, A; Holt, W V; Muiño-Blanco, T; Cebrián-Pérez, J A

    2012-01-01

    Egg yolk and milk are the 2 major membrane cryoprotectants commonly used in freezing media for the long-term preservation of semen (alone or in combination with others). However, in recent years, there have been increasing arguments against the use of egg yolk or milk because of the risk of introducing diseases through the use of cryopreserved semen. In this study, we analyzed the protective effect of lecithin as an alternative to egg yolk for the cryopreservation of ram semen, using a range of functional markers for sperm viability, motility, apoptosis, and mitochondrial functionality analyses (mitochondrial inner membrane surface [MIMS], mitochondrial inner membrane potential [MIMP], and cell membrane potential) as methods of assessment in samples diluted in 3 different media: Tris-citrate-glucose as control and 2 media supplemented with soy lecithin or egg yolk. The results showed that lecithin was able to effectively protect certain sperm quality characteristics against freezing-induced damage. However, lecithin induced loss of mitochondrial membrane potential or mitochondrial loss that was not reflected by modifications in sperm motility in fresh semen. MIMS and MIMP values decreased in thawed lecithin-treated samples, concomitant with a lower (P lecithin may have affected the inner mitochondrial membrane in frozenthawed spermatozoa and confirmed that sublethal damages that seriously affect sperm functionality, not detected by classic sperm quality analyses, can be evidenced by changes in the inner mitochondrial membrane surface. These findings strengthen the relationship between mitochondrial membrane potential and motility and show that the mitochondrial alterations induced by the cryopreservation process could be specific targets for the improvement of semen cryopreservation protocols.

  17. Effect of freeze-thaw cycling on grain size of biochar.

    Science.gov (United States)

    Liu, Zuolin; Dugan, Brandon; Masiello, Caroline A; Wahab, Leila M; Gonnermann, Helge M; Nittrouer, Jeffrey A

    2018-01-01

    Biochar may improve soil hydrology by altering soil porosity, density, hydraulic conductivity, and water-holding capacity. These properties are associated with the grain size distributions of both soil and biochar, and therefore may change as biochar weathers. Here we report how freeze-thaw (F-T) cycling impacts the grain size of pine, mesquite, miscanthus, and sewage waste biochars under two drainage conditions: undrained (all biochars) and a gravity-drained experiment (mesquite biochar only). In the undrained experiment plant biochars showed a decrease in median grain size and a change in grain-size distribution consistent with the flaking off of thin layers from the biochar surface. Biochar grain size distribution changed from unimodal to bimodal, with lower peaks and wider distributions. For plant biochars the median grain size decreased by up to 45.8% and the grain aspect ratio increased by up to 22.4% after 20 F-T cycles. F-T cycling did not change the grain size or aspect ratio of sewage waste biochar. We also observed changes in the skeletal density of biochars (maximum increase of 1.3%), envelope density (maximum decrease of 12.2%), and intraporosity (porosity inside particles, maximum increase of 3.2%). In the drained experiment, mesquite biochar exhibited a decrease of median grain size (up to 4.2%) and no change of aspect ratio after 10 F-T cycles. We also document a positive relationship between grain size decrease and initial water content, suggesting that, biochar properties that increase water content, like high intraporosity and pore connectivity large intrapores, and hydrophilicity, combined with undrained conditions and frequent F-T cycles may increase biochar breakdown. The observed changes in biochar particle size and shape can be expected to alter hydrologic properties, and thus may impact both plant growth and the hydrologic cycle.

  18. Freeze-all policy: fresh vs. frozen-thawed embryo transfer.

    Science.gov (United States)

    Roque, Matheus; Valle, Marcello; Guimarães, Fernando; Sampaio, Marcos; Geber, Selmo

    2015-05-01

    To compare in vitro fertilization (IVF) outcomes between fresh embryo transfer (ET) and frozen-thawed ET (the "freeze-all" policy), with fresh ET performed only in cases without progesterone (P) elevation. Prospective, observational, cohort study. Private IVF center. A total of 530 patients submitted to controlled ovarian stimulation (COS) with a gonadotropin-releasing hormone-antagonist protocol, and cleavage-stage, day-3 ET. None. Ongoing pregnancy rates. A total of 530 cycles were included in the analysis: 351 in the fresh ET group (when P levels were ≤1.5 ng/mL on the trigger day); and 179 cycles in the freeze-all group (ET performed after endometrial priming with estradiol valerate, at 6 mg/d, taken orally). For the fresh ET group vs. the freeze-all group, respectively, the implantation rate was 19.9% and 26.5%; clinical pregnancy rate was 35.9% and 46.4%; and ongoing pregnancy rate was 31.1% and 39.7%. The IVF outcomes were significantly better in the group using the freeze-all policy, compared with the group using fresh ET. These results suggest that even in a select group of patients that underwent fresh ET (P levels ≤1.5 ng/mL), endometrial receptivity may have been impaired by COS, and outcomes may be improved by using the freeze-all policy. Copyright © 2015 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

  19. Behaviour of Prestressed CFRP Anchorages during and after Freeze-Thaw Cycle Exposure

    Directory of Open Access Journals (Sweden)

    Yunus Emre Harmanci

    2018-05-01

    Full Text Available The long-term performance of externally-bonded reinforcements (EBR on reinforced concrete (RC structures highly depends on the behavior of constituent materials and their interfaces to various environmental loads, such as temperature and humidity exposure. Although significant efforts have been devoted to understanding the effect of such conditions on the anchorage resistance of unstressed EBR, with or without sustained loading, the effect of a released prestressing has not been thoroughly investigated. For this purpose, a series of experiments has been carried out herein, with concrete blocks strengthened with carbon fiber-reinforced polymer (CFRP strips, both unstressed, as well as prestressed using the gradient anchorage. The gradient anchorage is a non-mechanical technique to anchor prestressed CFRP by exploiting the accelerated curing property of epoxy under higher temperatures and segment-wise prestress-force releasing. Subsequently, strengthened blocks are transferred into a chamber for exposure in dry freeze-thaw cycles (FTC. Following FTC exposure, the blocks are tested in a conventional lap-shear test setup to determine their residual anchorage resistance and then compared with reference specimens. Blocks were monitored during FTC by conventional and Fabry–Pérot-based fiber optic strain (FOS sensors and a 3D-digital image correlation (3D-DIC system during gradient application and lap-shear testing. Results indicate a reduction of residual anchorage resistance, stiffness and deformation capacity of the system after FTC and a change in the failure mode from concrete substrate to epoxy-concrete interface failure. It was further observed that all of these properties experienced a more significant reduction for prestressed specimens. These findings are presented with a complementary finite element model to shed more light onto the durability of such systems.

  20. EM International. Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    1993-07-01

    It is the intent of EM International to describe the Office of Environmental Restoration and Waste Management`s (EM`s) various roles and responsibilities within the international community. Cooperative agreements and programs, descriptions of projects and technologies, and synopses of visits to international sites are all highlighted in this semiannual journal. Focus on EM programs in this issue is on international collaboration in vitrification projects. Technology highlights covers: in situ sealing for contaminated sites; and remote sensors for toxic pollutants. Section on profiles of countries includes: Arctic contamination by the former Soviet Union, and EM activities with Germany--cooperative arrangements.

  1. Effects of supplemental seminal plasma on cryopreserved boar ...

    African Journals Online (AJOL)

    To analyse the effects of supplemental autologous seminal plasma on boar semen quality before freezing and after thawing, thirty ejaculates were collected from six Pietrain boars. The main factors of a 2 x 2 x 2 factorial arrangement of treatments were Beltsville thawing solution (BTS), seminal plasma before freezing, and ...

  2. Effect of cryoprotectant on the cryopreservation of | Mapeka | South ...

    African Journals Online (AJOL)

    The study evaluated the effect of different cryoprotectants on post-thaw survival and motility of Kolbroek sperm. Semen from Kolbroek boars was collected with the gloved hand technique. Ejaculates were diluted with Beltsville thawing solution (BTS) at a ratio of 1 : 1 prior to freezing. Semen was diluted with egg yolk tris; ...

  3. 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.

  4. Brown bear sperm double freezing: Effect of elapsed time and use of PureSperm(®) gradient between freeze-thaw cycles.

    Science.gov (United States)

    Alvarez-Rodríguez, Manuel; Alvarez, Mercedes; López-Urueña, Elena; Martínez-Rodriguez, Carmen; Borragan, Santiago; Anel-López, Luis; de Paz, Paulino; Anel, Luis

    2013-12-01

    The use of sexed spermatozoa has great potential to captive population management in endangered wildlife. The problem is that the sex-sorting facility is a long distance from the semen collection place and to overcome this difficulty two freeze-thaw cycles may be necessary. In this study, effects of refreezing on brown bear electroejaculated spermatozoa were analyzed. We carried out two experiments: (1) to assess the effects of the two freezing-thawing cycles on sperm quality and to analyze three different elapsed times between freezing-thawing cycles (30, 90 and 180 min), and (2) to analyze the use of PureSperm between freezing-thawing cycles to select a more motile and viable sperm subpopulation which better survived first freezing. The motility, viability and undamaged acrosomes were significantly reduced after the second thawing respect to first thawing into each elapsed time group, but the elapsed times did not significantly affect the viability and acrosome status although motility was damaged. Our results with the PureSperm gradient showed higher values of viability in freezability of select sample (pellet) respect to the rest of the groups and it also showed a significant decrease in the number of acrosome damaged. In summary, the double freezing of bear semen selected by gradient centrifugation is qualitatively efficient, and thus could be useful to carry out a sex-sorting of frozen-thawed bear spermatozoa before to send the cryopreserved sample to a biobank. Given the low recovery of spermatozoa after applying a selection gradient, further studies will be needed to increase the recovery rate without damaging of the cell quality. Copyright © 2013 Elsevier Inc. All rights reserved.

  5. Effect of sequence of insemination after simultaneous thawing of multiple semen straws on conception rate to timed AI in suckled multiparous Nelore cows.

    Science.gov (United States)

    Oliveira, L Z; Arruda, R P; de Andrade, A F C; Santos, R M; Beletti, M E; Peres, R F G; Martins, J P N; de Lima, V F M Hossepian

    2012-11-01

    The objective was to determine the effect of sequence of insemination after simultaneous thawing of multiple 0.5 mL semen straws on conception rate in suckled multiparous Nelore cows. The effect of this thawing procedure on in vitro sperm characteristics was also evaluated. All cows (N = 944) received the same timed AI protocol. Ten straws (0.5 mL) of frozen semen from the same batch were simultaneously thawed at 36 °C, for a minimum of 30 sec. One straw per cow was used for timed AI. Frozen semen from three Angus bulls was used. Timed AI records included sequence of insemination (first to tenth) and time of semen removal from thawing bath. For laboratory analyses, the same semen batches used in the field experiment were evaluated. Ten frozen straws from the same batch were thawed simultaneously in a thawing unit identical to that used in the field experiment. The following sperm characteristics were analyzed: sperm motility parameters, sperm thermal resistance, plasma and acrosomal membrane integrity, lipid peroxidation, chromatin structure, and sperm morphometry. Based on logistic regression, there were no significant effects of breeding group, body condition score, AI technician, and sire on conception rate, but there was an interaction between sire and straw group (P = 0.002). Semen from only one bull had decreased (P conception rates at timed AI, depending on the sire used. Nevertheless, the effects of this thawing environment on in vitro sperm characteristics, remain to be further investigated. Copyright © 2012 Elsevier Inc. All rights reserved.

  6. Effect of semen extenders on frozen-thawed boar sperm characteristics and distribution in the female genital tract after deep intrauterine insemination in sows.

    Science.gov (United States)

    Noguchi, Michiko; Yoshioka, Koji; Hikono, Hirokazu; Suzuki, Chie; Kikuchi, Kazuhiro

    2015-12-01

    We compared the effects of extenders of frozen-thawed semen on post-thaw sperm characteristics and the distribution of frozen-thawed spermatozoa in the female genital tract after fixed-timed deep intrauterine insemination (DIUI) in sows. Frozen semen samples were thawed and diluted in either modified Modena solution (mMS) or porcine fertilization medium (PFM) containing theophylline, adenosine and cysteine. Sperm quality, assessed in vitro based on motility using a computer-assisted sperm analyzer and the integrity of the plasma and acrosomal membranes using flow cytometry, was evaluated at 0.5, 1.5, 3 and 6h after thawing. Progressive motility and the percentage of spermatozoa with damaged acrosomal membranes in PFM were significantly better than in mMS throughout the 6h. Sows with estrus synchronized using prostaglandin F2 alpha, equine chorionic gonadotropin and human chorionic gonadotropin (hCG) were inseminated once with mMS- or PFM-diluted 5 × 10(8) frozen-thawed spermatozoa by DIUI at 34 h after the hCG injection. At 4h after DIUI, reproductive tracts were recovered from 30 sows. There were significantly fewer polymorphonuclear leukocytes (PMNs) and more spermatozoa outside PMNs in the uterine horn after PFM treatment than with mMS. When 22 sows were administered DIUI with 10 × 10(8) frozen-thawed spermatozoa at 36 h after hCG, the pregnancy rates did not differ significantly between the mMS- (36%) and PFM- (64%) treated groups. Thus, PFM enhanced progressive sperm motility but increased sperm membrane damage compared with mMS; it also suppressed the migration of PMNs into the uterine lumen. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Decrease in glutathione content in boar sperm after cryopreservation. Effect of the addition of reduced glutathione to the freezing and thawing extenders.

    Science.gov (United States)

    Gadea, Joaquín; Sellés, Elena; Marco, Marco Antonio; Coy, Pilar; Matás, Carmen; Romar, Raquel; Ruiz, Salvador

    2004-08-01

    Although glutathione content in boar spermatozoa has been previously reported, the effect of reduced glutathione (GSH) on semen parameters and the fertilizing ability of boar spermatozoa after cryopreservation has never been evaluated. In this study, GSH content was determined in ejaculated boar spermatozoa before and after cryopreservation. Semen samples were centrifuged and GSH content in the resulting pellet monitored spectrophotometrically. The fertilizing ability of frozen-thawed boar sperm was also tested in vitro by incubating sperm with in vitro matured oocytes obtained from gilts. GSH content in fresh semen was 3.84 +/- 0.21 nM GSH/10(8) sperm. Following semen cryopreservation, there was a 32% decrease in GSH content (P boars and after various preservation protocols (P = 0.0102 ). The effect of addition of GSH to the freezing and thawing extenders was also evaluated. Addition of 5 mM GSH to the freezing extender did not have a significant effect on standard semen parameters or sperm fertilizing ability after thawing. In contrast, when GSH was added to the thawing extender, a dose-dependent tendency to increase in sperm fertilizing ability was observed, although no differences were observed in standard semen parameters. In summary, (i) there was a loss in GSH content after cryopreservation of boar semen; (ii) addition of GSH to the freezing extender did not result in any improvement in either standard semen parameters or sperm fertilizing ability; and (iii) addition of GSH to the thawing extender resulted in a significant increase in sperm fertilizing ability. Nevertheless, future studies must conclude if this is the case for all boars. Furthermore, since addition of GSH to the thawing extender did not result in an improvement in standard semen parameters, this suggests that during the thawing process, GSH prevents damage of a sperm property that is critical in the fertilization process but that is not measured in the routine semen analysis.

  8. Microsatellite Loci in the Gypsophyte <em>Lepidium subulatum em>(Brassicaceae, and Transferability to Other <em>Lepidieae>

    Directory of Open Access Journals (Sweden)

    José Gabriel Segarra-Moragues

    2012-09-01

    Full Text Available Polymorphic microsatellite markers were developed for the Ibero-North African, strict gypsophyte <em>Lepidium subulatumem> to unravel the effects of habitat fragmentation in levels of genetic diversity, genetic structure and gene flow among its populations. Using 454 pyrosequencing 12 microsatellite loci including di- and tri-nucleotide repeats were characterized in <em>L. subulatumem>. They amplified a total of 80 alleles (2–12 alleles per locus in a sample of 35 individuals of <em>L. subulatumem>, showing relatively high levels of genetic diversity, <em>H>O = 0.645, <em>H>E = 0.627. Cross-species transferability of all 12 loci was successful for the Iberian endemics <em>Lepidium cardaminesem>, <em>Lepidium stylatumem>, and the widespread, <em>Lepidium graminifoliumem> and one species each of two related genera, <em>Cardaria drabaem> and <em>Coronopus didymusem>. These microsatellite primers will be useful to investigate genetic diversity, population structure and to address conservation genetics in species of <em>Lepidium>.

  9. Analysis of the influence of pasteurization, freezing/thawing, and offer processes on human milk's macronutrient concentrations.

    Science.gov (United States)

    Vieira, Alan Araujo; Soares, Fernanda Valente Mendes; Pimenta, Hellen Porto; Abranches, Andrea Dunshee; Moreira, Maria Elisabeth Lopes

    2011-08-01

    The macronutrient concentrations of human milk could be influenced by the various processes used in human milk bank. To determine the effect of various process (Holder pasteurization, freezing and thawing and feeding method) on the macronutrient concentration of human milk. The samples of donated fresh human milk were studied before and after each process (Holder pasteurization, freezing and thawing and feeding method) until their delivery to newborn infants. Fifty-seven raw human milk samples were analyzed in the first step (pasteurization) and 228 in the offer step. Repeated measurements of protein, fat and lactose amounts were made in samples of human milk using an Infrared analyzer. The influence of repeated processes on the mean concentration of macronutrients in donor human milk was analyzed by repeated measurements ANOVA, using R statistical package. The most variable macronutrient concentration in the analyzed samples was fat (reduction of 59%). There was a significant reduction of fat and protein mean concentrations following pasteurization (5.5 and 3.9%, respectively). The speed at which the milk was thawed didn't cause a significant variation in the macronutrients concentrations. However, the continuous infusion delivery significantly reduced the fat concentration. When the influence of repeated processes was analyzed, the fat and protein concentrations varied significantly (reduction of 56.6% and 10.1% respectively) (Pmilk is submitted before delivery to newborn infants cause a reduction in the fat and protein concentration. The magnitude of this decrease is higher on the fat concentration and it needs to be considered when this processed milk is used to feed preterm infants. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  10. Dissolved organic matter composition of winter flow in the Yukon River basin: Implications of permafrost thaw and increased groundwater discharge

    Science.gov (United States)

    O'Donnell, Jonathan A.; Aiken, George R.; Walvoord, Michelle Ann; Butler, Kenna D.

    2012-01-01

    Groundwater discharge to rivers has increased in recent decades across the circumpolar region and has been attributed to thawing permafrost in arctic and subarctic watersheds. Permafrost-driven changes in groundwater discharge will alter the flux of dissolved organic carbon (DOC) in rivers, yet little is known about the chemical composition and reactivity of dissolved organic matter (DOM) of groundwater in permafrost settings. Here, we characterize DOM composition of winter flow in 60 rivers and streams of the Yukon River basin to evaluate the biogeochemical consequences of enhanced groundwater discharge associated with permafrost thaw. DOC concentration of winter flow averaged 3.9 ± 0.5 mg C L−1, yet was highly variable across basins (ranging from 20 mg C L−1). In comparison to the summer-autumn period, DOM composition of winter flow had lower aromaticity (as indicated by specific ultraviolet absorbance at 254 nm, or SUVA254), lower hydrophobic acid content, and a higher proportion of hydrophilic compounds (HPI). Fluorescence spectroscopy and parallel factor analysis indicated enrichment of protein-like fluorophores in some, but not all, winter flow samples. The ratio of DOC to dissolved organic nitrogen, an indicator of DOM biodegradability, was positively correlated with SUVA254 and negatively correlated with the percentage of protein-like compounds. Using a simple two-pool mixing model, we evaluate possible changes in DOM during the summer-autumn period across a range of conditions reflecting possible increases in groundwater discharge. Across three watersheds, we consistently observed decreases in DOC concentration and SUVA254 and increases in HPI with increasing groundwater discharge. Spatial patterns in DOM composition of winter flow appear to reflect differences in the relative contributions of groundwater from suprapermafrost and subpermafrost aquifers across watersheds. Our findings call for more explicit consideration of DOC loss and stabilization

  11. Interpreting Carbon Fluxes from a Spatially Heterogeneous Peatland with Thawing Permafrost: Scaling from Plant Community Scale to Ecosystem Scale

    Science.gov (United States)

    Harder, S. R.; Roulet, N. T.; Strachan, I. B.; Crill, P. M.; Persson, A.; Pelletier, L.; Watt, C.

    2014-12-01

    Various microforms, created by spatial differential thawing of permafrost, make up the subarctic heterogeneous Stordalen peatland complex (68°22'N, 19°03'E), near Abisko, Sweden. This results in significantly different peatland vegetation communities across short distances, as well as differences in wetness, temperature and peat substrates. We have been measuring the spatially integrated CO2, heat and water vapour fluxes from this peatland complex using eddy covariance and the CO2 exchange from specific plant communities within the EC tower footprint since spring 2008. With this data we are examining if it is possible to derive the spatially integrated ecosystem-wide fluxes from community-level simple light use efficiency (LUE) and ecosystem respiration (ER) models. These models have been developed using several years of continuous autochamber flux measurements for the three major plant functional types (PFTs) as well as knowledge of the spatial variability of the vegetation, water table and active layer depths. LIDAR was used to produce a 1 m resolution digital evaluation model of the complex and the spatial distribution of PFTs was obtained from concurrent high-resolution digital colour air photography trained from vegetation surveys. Continuous water table depths have been measured for four years at over 40 locations in the complex, and peat temperatures and active layer depths are surveyed every 10 days at more than 100 locations. The EC footprint is calculated for every half-hour and the PFT based models are run with the corresponding environmental variables weighted for the PFTs within the EC footprint. Our results show that the Sphagnum, palsa, and sedge PFTs have distinctly different LUE models, and that the tower fluxes are dominated by a blend of the Sphagnum and palsa PFTs. We also see a distinctly different energy partitioning between the fetches containing intact palsa and those with thawed palsa: the evaporative efficiency is higher and the Bowen

  12. Freeze-Thaw Cycle Test on Basalt, Diorite and Tuff Specimens with the Simulated Ground Temperature of Antarctica

    Science.gov (United States)

    Park, J.; Hyun, C.; Cho, H.; Park, H.

    2010-12-01

    Physical weathering caused by freeze-thaw action in cold regions was simulated with artificial weathering simulator in laboratory. Physical weathering of rock in cold regions usually depends on the temperature, rock type and moisture content. Then these three variables were considered in this study. The laboratory freeze-thaw tests were conducted on the three types of rocks, e.g. diorite, basalt and tuff, which are the major rock types around Sejong Station, King George Island, Antarctica. Nine core samples composed of three samples from each rock type were prepared in NX core, and 50 cycles of freeze-thaw test was carried out under dried and saturated water conditions. In this study, the physical weathering of rocks was investigated after each 10 cycles by measuring P-wave velocity, bulk density, effective porosity, Schmidt hardness and uniaxial compression strength(UCS). The experimental result of the diorite and the tuff specimens showed that P-wave velocity, bulk density, effective porosity, Schmidt hardness and UCS were gradually decreased as weathering progresses, but the result of the basalt specimens did not show typical trends due to the characteristics of irregular pore distribution and various pore sizes. Scanning electron microscopy(SEM) photographs of diorite, basalt and tuff specimens weathered in dried and saturated conditions were also acquired to investigate the role of water during physical weathering processes. The number and size of microcracks were increased as weathering progresses. This work was supported by the National Research Foundation of Korea(NRF) Grant(NRF-2010-0027753).

  13. Using dissolved organic matter age and composition to detect permafrost thaw in boreal watersheds of interior Alaska

    Science.gov (United States)

    O'Donnell, Jonathan A.; Aiken, George R.; Walvoord, Michelle A.; Raymond, Peter A.; Butler, Kenna D.; Dornblaser, Mark M.; Heckman, Katherine

    2014-11-01

    Recent warming at high latitudes has accelerated permafrost thaw, which can modify soil carbon dynamics and watershed hydrology. The flux and composition of dissolved organic matter (DOM) from soils to rivers are sensitive to permafrost configuration and its impact on subsurface hydrology and groundwater discharge. Here, we evaluate the utility of DOM composition and age as a tool for detecting permafrost thaw in three rivers (Beaver, Birch, and Hess Creeks) within the discontinuous permafrost zone of interior Alaska. We observed strong temporal controls on Δ14C content of hydrophobic acid isolates (Δ14C-HPOA) across all rivers, with the most enriched values occurring during spring snowmelt (75 ± 8‰) and most depleted during winter flow (-21 ± 8‰). Radiocarbon ages of winter flow samples ranged from 35 to 445 yr BP, closely tracking estimated median base flow travel times for this region (335 years). During spring snowmelt, young DOM was composed of highly aromatic, high molecular-weight compounds, whereas older DOM of winter flow had lower aromaticity and molecular weight. We observed a significant correlation between Δ14C-HPOA and UV absorbance coefficient at 254 nm (α254) across all study rivers. Using α254 as an optical indicator for Δ14C-HPOA, we also observed a long-term decline in α254 during maximum annual thaw depth over the last decade at the Hess Creek study site. These findings suggest a shift in watershed hydrology associated with increasing active layer thickness. Further development of DOM optical indicators may serve as a novel and inexpensive tool for detecting permafrost degradation in northern watersheds.

  14. 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.

  15. 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.

  16. Use of ground-based radiometers for L-Band Freeze/Thaw retrieval in a boreal forest site

    Science.gov (United States)

    Roy, A.; Sonnentag, O.; Derksen, C.; Toose, P.; Pappas, C.; Mavrovic, A.; El Amine, M.; Royer, A.; Berg, A. A.; Rowlandson, T. L.; Barr, A.; Black, T. A.

    2017-12-01

    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 the seasonal freeze/thaw (F/T) state influences vegetation developmental stages (phenology) and, consequently, constitutes an important control on how boreal forest ecosystems exchange carbon, water and energy with the atmosphere. Recently, new L-Band satellite-derived F/T information has become available. However, disentangling the seasonally differing contributions from forest overstory and understory vegetation, and the ground surface to the satellite signal remains challenging. Here we present results from an ongoing campaign with two L-Band surface-based radiometers (SBR) installed on a micrometeorological tower at the Southern Old Black Spruce site (53.99°N / 105.12°W) in central Saskatchewan. One radiometer unit is installed on top of the tower viewing the multi-layer vegetation canopy from above. A second radiometer unit is installed within the multi-layer canopy, viewing the understory and the ground surface only. The objectives of our study are to (i) disentangle the L-Band F/T signal contribution of boreal forest overstory from the combined understory and ground surface contribution, and (ii) link the L-Band F/T signal to related boreal forest structural and functional characteristics. Analysis of these radiometer measurements made from September to November 2016 shows that when the ground surface is thawed, the main contributor to both radiometer signals is soil moisture. The Pearson correlation coefficient between brightness temperature (TB) at vertical polarization (V-pol) and soil permittivity is 0.79 for the radiometer above the canopy and 0.74 for the radiometer below the canopy. Under cold conditions when the soil was thawed (snow insulation) and the trees were frozen (below 0°C), TB at V-pol is negatively correlated with tree permittivity. The freezing tree contribution to

  17. 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

  18. Soil respiration and carbon loss relationship with temperature and land use conversion in freeze-thaw agricultural area.

    Science.gov (United States)

    Ouyang, Wei; Lai, Xuehui; Li, Xia; Liu, Heying; Lin, Chunye; Hao, Fanghua

    2015-11-15

    Soil respiration (Rs) was hypothesized to have a special response pattern to soil temperature and land use conversion in the freeze-thaw area. The Rs differences of eight types of land use conversions during agricultural development were observed and the impacts of Rs on soil organic carbon (SOC) loss were assessed. The land use conversions during last three decades were categorized into eight types, and the 141 SOC sampling sites were grouped by conversion type. The typical soil sampling sites were subsequently selected for monitoring of soil temperature and Rs of each land use conversion types. The Rs correlations with temperature at difference depths and different conversion types were identified with statistical analysis. The empirical mean error model and the biophysical theoretical model with Arrhenius equation about the Rs sensitivity to temperature were both analyzed and shared the similar patterns. The temperature dependence of soil respiration (Q10) analysis further demonstrated that the averaged value of eight types of land use in this freeze-thaw agricultural area ranged from 1.15 to 1.73, which was lower than the other cold areas. The temperature dependence analysis demonstrated that the Rs in the top layer of natural land covers was more sensitive to temperature and experienced a large vertical difference. The natural land covers exhibited smaller Rs and the farmlands had the bigger value due to tillage practices. The positive relationships between SOC loss and Rs were identified, which demonstrated that Rs was the key chain for SOC loss during land use conversion. The spatial-vertical distributions of SOC concentration with the 1.5-km grid sampling showed that the more SOC loss in the farmland, which was coincided with the higher Rs in farmlands. The analysis of Rs dynamics provided an innovative explanation for SOC loss in the freeze-thaw agricultural area. The analysis of Rs dynamics provided an innovative explanation for SOC loss in the freeze-thaw

  19. Micro-fractures produced in the Cadalso de los Vidrios granite (Madrid) subjected to Freeze-Thaw Durability Testing

    Science.gov (United States)

    Freire-Lista, D. M.; Varas-Muriel, M. J.; Fort, R.

    2012-04-01

    A specific leucogranite (fine to medium grain sized) from Cadalso de los Vidrios, Madrid, Spain, from where it takes the name of the stone variety, which is a traditional heritage building material used in Central Spain, was subjected to freezing-thaw durability tests or accelerated artificial ageing tests (according to Spanish standard EN 12371:2001) to assess its durability by means of ultrasonic velocity measurements (a non-destructive technique), and optical and fluorescence petrography using a polarized optical microscope (destructive technique), both techniques used before, during and after laboratory ageing tests, or in other words, what is determined is the improvement or deterioration in some properties. The measurement of the ultrasonic velocity in the leucogranite cubic test specimens along the freezing-thaw cycles shown that the velocity diminishes with the number of cycles, in relation to the decay that the stones were experiencing. This deterioration can be observed by the loss of crystalline minerals in the surface of the analyzed samples and by the micro-fractures appearance up to one centimeter deep, which have been detected by the petrographic techniques previously mentioned. The images taken by means of the fluorescence microscope clearly show the micro-fractures generated during the durability test. These images have been processed and analyzed by the UTHSCSA Image Tool program with the purpose of being able to quantify the degree of decay that this type of crystalline materials undergone, when subjected to a number of freezing-thaw test cycles. It is therefore an effective, reliable and complementary technique to that of the petrography analysis, both optical and fluorescence ones. In the first cycles of the ageing test, the micro-fractures propagate along crystals edges and during the last cycles of the test, intracrystalline micro-fractures are generated, which are developed in different ways depending on the mineralogy of the crystals. Thus

  20. A Micro-Scale Investigation on the Behaviors of Asphalt Mixtures under Freeze-Thaw Cycles Using Entropy Theory and a Computerized Tomography Scanning Technique

    Directory of Open Access Journals (Sweden)

    Huining Xu

    2018-01-01

    Full Text Available The thermodynamic behavior of asphalt mixtures is critical to the engineers since it directly relates to the damage in asphalt mixtures. However, most of the current research of the freeze-thaw damage of asphalt mixtures is focused on the bulk body from the macroscale and lacks a fundamental understanding of the thermodynamic behaviors of asphalt mixtures from the microscale perspective. In this paper, to identify the important thermodynamic behaviors of asphalt mixtures under freeze-thaw loading cycle, the information entropy theory, an X-ray computerized tomography (CT scanner and digital image processing technology are employed. The voids, the average size of the voids, the connected porosity, and the void number are extracted according to the scanned images. Based on the experiments and the CT scanned images, the information entropy evolution of the asphalt mixtures under different freeze-thaw cycles is calculated and the relationship between the change of information entropy and the pore structure characteristics is established. Then, the influences of different freezing and thawing conditions on the thermodynamic behaviors of asphalt mixtures are compared. The combination of information entropy theory and CT scanning technique proposed in this paper provides an innovative approach to investigate the thermodynamics behaviors of asphalt mixtures and a new way to analyze the freeze-thaw damage in asphalt mixtures.

  1. 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 o