975 resultados para freezing-thawing


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Icing is the practice for preserving prawns on board fishing boats in India. Majority of these boats need to preserve the catch only for a few hours because of the short duration of the fishing trip. However, with the anticipated introduction of a considerable number of bigger fishing vessels which can remain in the fishing ground for longer periods, more than fortnight, preservation methods, other than icing are required to retain prime quality. Freezing and cold storage of whole prawns on board followed by thawing and processing on land is a possible proposition. The extent of quality loss in prawns during these operations is one of the important points to be considered. Hence, laboratory scale studies were undertaken on double freezing of prawns and the results are dealt within this communication.

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Prawn meat which was never in contact with ice or water prior to freezing was frozen at -30°C and was studied up to six months of storage at -23°C for thawing losses and cooked characteristics of the thawed material. Thawing loss was nil in unwashed samples after three days of storage and it gradually increased to 6.6% after 6 months compared to 6.0 and 18.2% in the washed samples during the same periods. It is inferred that the high thawing losses observed in commercial frozen prawn meat immediately after freezing may be mainly an after effect of the water imbibed during the pre-freezing stages. During frozen storage, the changes in texture observed by sensory methods on the cooked product were more in the washed sample indicating that the imbibed water or constituents washed out of the tissue play an important role in textural changes in prawn meat during frozen storage.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Valuable genetic material can be preserved by the cryopreservation of epididymal sperm. This study evaluated the viability of pre-freezing and post-thawed sperm samples recovered from the epididymal cauda of buffaloes. Epididymides from eight Murrah buffaloes with 18 months of age were used. Semen samples were diluted in two different freezing extenders: Botu-bov (BB) and Tris (TRIS). Immediately after slaughter, both testicles from each animal were collected and transported at 4 degrees C for six hours interval. In laboratory, the removed epididymides were flushed to obtain sperm and the fractions were diluted in both freezing extenders (BB and TRIS). Semen doses were analyzed before and after frozen at -196 degrees C. BB and TRIS pre-freezing results were 38.54 +/- 22.33%(b) and 14.17 +/- 12.78%(a) for total motility (TM), 25.00 +/- 16.12(a) and 9.44 +/- 9.11(a) for progressive motility (PM), 7.21 +/- 0.98(a) and 5.09 +/- 2.65(a) for percentage of rapid cells (RAP), 91.08 +/- 12.53(b) and 63.33 +/- 31.47(a) for velocity of trajectory (VAP), 73.54 +/- 20.17(b) and 49.50 +/- 9.11(a) for linear progressive velocity (VSL), 172.21 +/- 24.55(a) and 116.94 +/- 59.48(a) for curvilinear velocity (VCL), respectively (P < 0.05). BB and TRIS post-thawing results were 42.25 +/- 21.50(b) and 17.62 +/- 19.46(a) for TM, 27.25 +/- 24.86(a) and 18.00 +/- 13.68(a) for PM, 7.35 +/- 0.98(a) and 6.26 +/- 1.13(a) for RAP, 91.42 +/- 16.86(a) and 75.96 +/- 13.17(a) for VAP, 67.96 +/- 12.13(a) and 60.04 +/- 10.42(a) for VSL, 177.54 +/- 23.53(b) and 141.29 +/- 24.97a for VCL, respectively (P < 0.05). The sperm recovered from the epididymal cauda, after 6 h storage of epididymides at 5 degrees C ensures sperm preservation demonstrating that the diluent Botu-bov had higher total motility both pre-and post-freezing when compared with TRIS. Additionally, the sperm frozen with the diluent Botu-bov showed higher values of VSL at post-thawing. These findings may reflect in improvement of conception rates.

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The cryopreservation of epididymal sperm is important to preserve genetic material from valuable buffalo bulls. This study evaluated the viability of post-thawed sperm samples recovered from the epididymal cauda adding motility inductors. For that, were used epididymides from eight Murrah buffaloes with 18 months of age. Semen samples were submitted to three different conditions: (CT - control) without adding medium, (SPERM) adding Sperm Talp medium, and (FERT) adding Fert Talp medium. Immediately after slaughter, both testicles from each animal were collected and transported at 4 degrees C at maximum six hours interval. In laboratory, the removed epididymides was flushed to obtain sperm and diluted in the freezing extender. Each buffalo sperm were divided and fractions were submitted to all conditions (CT, SPERM and FERT). Semen doses were frozen at -196 degrees C. CT, SPERM and FERT post-thawing results were 13.63 +/- 8.91, 38.77 +/- 8.91 and 42.83 +/- 8.91 for total motility, 7.30 +/- 8.74, 24.87 +/- 8.74 and 29.70 +/- 8.74 for progressive motility, 6.04 +/- 0.92, 6.74 +/- 0.92 and 6.93 +/- 0.92 for percentage of rapid cells (P < 0.05). In conclusion, diluted semen supplementation with Sperm or Fert talp increases the motility of cauda epididymal sperm of buffalo bulls.

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The objectives were to evaluate the reexpansion blastocoele rate, post-thaw viability, and in vitro development of canine blastocysts cryopreserved by slow freezing in 1.0 m glycerol (GLY) or 1.5 m ethylene glycol (EG). Fifty-one in vivo-produced canine blastocysts were randomly allocated in two groups: GLY (n = 26) and EG (n = 25). After thawing, embryos from MO were immediately stained with the fluorescent probes propidium iodide and Hoechst 33 342 to evaluate cellular viability. Frozen-thawed embryos from M3 and M6 were cultured in SOFaa medium + 10% FCS at 38.5 degrees C under an atmosphere of 5% CO2 with maximum humidity, for 3 and 6 days, respectively, and similarly stained. The blastocoele reexpansion rate (24 h after in vitro culture) did not differ between GLY (76.5%) and EG (68.8%). Post-thaw viable cells rate were not significantly different between GLY and EG (66.5 +/- 4.8 and 57.3 +/- 4.8, respectively, mean +/- SEM), or among MO (62.3 +/- 5.7%), M3 (56.9 +/- 6.0%), and M6 (66.5 +/- 6.0%). In conclusion, canine blastocysts cryopreserved by slow freezing in 1.0 m glycerol or 1.5 m ethylene glycol, had satisfactory blastocoele reexpansion rates, similar post-thawing viability, and remained viable for up to 6 days of in vitro culture. (C) 2012 Elsevier Inc. All rights reserved.

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Amniotic fluid (AF) was described as a potential source of mesenchymal stem cells (MSCs) for biomedicine purposes. Therefore, evaluation of alternative cryoprotectants and freezing protocols capable to maintain the viability and stemness of these cells after cooling is still needed. AF stem cells (AFSCs) were tested for different freezing methods and cryoprotectants. Cell viability, gene expression, surface markers, and plasticity were evaluated after thawing. AFSCs expressed undifferentiated genes Oct4 and Nanog; presented typical markers (CD29, CD44, CD90, and CD105) and were able to differentiate into mesenchymal lineages. All tested cryoprotectants preserved the features of AFSCs however, variations in cell viability were observed. In this concern, dimethyl sulfoxide (Me2SO) showed the best results. The freezing protocols tested did not promote significant changes in the AFSCs viability. Time programmed and nonprogrammed freezing methods could be used for successful AFSCs cryopreservation for 6 months. Although tested cryoprotectants maintained undifferentiated gene expression, typical markers, and plasticity of AFSCs, only Me2SO and glycerol presented workable viability ratios.

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Objective: To assess the efficacy of bilateral pedunculopontine nucleus (PPN) deep brain stimulation (DBS) as a treatment for primary progressive freezing of gait (PPFG). ------ ----- Methods: A patient with PPFG underwent bilateral PPN-DBS and was followed clinically for over 14 months. ------ ----- Results: The PPFG patient exhibited a robust improvement in gait and posture following PPN-DBS. When PPN stimulation was deactivated, postural stability and gait skills declined to pre-DBS levels, and fluoro-2-deoxy-d-glucose positron emission tomography revealed hypoactive cerebellar and brainstem regions, which significantly normalised when PPN stimulation was reactivated. ------ ----- Conclusions: This case demonstrates that the advantages of PPN-DBS may not be limited to addressing freezing of gait (FOG) in idiopathic Parkinson's disease. The PPN may also be an effective DBS target to address other forms of central gait failure.

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Failure of buried pipes due to reactive soil movement (e.g. shrinking/swelling) is a common problem for water and gas pipe networks in Australia and the world. Soil movement is closely related to seasonal climatic change, and particularly to the moisture content of soil. Although some research has been carried out to understand the effect of freezing and thawing of soils and temperature effects in colder climates, very limited research has been undertaken to examine the possible failure mechanisms of pipes buried in reactive soils. This study reports the responses of a 2 m long polyethylene pipe buried in reactive clay in a box under laboratory conditions. The soil and pipe movements were measured as the soil was wetted from the bottom of the box. It was observed that the pipe underwent substantial deformation as the soil swelled with increase of the moisture content. The results are explained with a simplified numerical analysis.

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Gait freezing is an episodic arrest of locomotion due to an inability to take normal steps. Pedunculopontine nucleus stimulation is an emerging therapy proposed to improve gait freezing, even where refractory to medication. However, the efficacy and precise effects of pedunculopontine nucleus stimulation on Parkinsonian gait disturbance are not established. The clinical application of this new therapy is controversial and it is unknown if bilateral stimulation is more effective than unilateral. Here, in a double-blinded study using objective spatiotemporal gait analysis, we assessed the impact of unilateral and bilateral pedunculopontine nucleus stimulation on triggered episodes of gait freezing and on background deficits of unconstrained gait in Parkinson’s disease. Under experimental conditions, while OFF medication, Parkinsonian patients with severe gait freezing implanted with pedunculopontine nucleus stimulators below the pontomesencephalic junction were assessed during three conditions; off stimulation, unilateral stimulation and bilateral stimulation. Results were compared to Parkinsonian patients without gait freezing matched for disease severity and healthy controls. Pedunculopontine nucleus stimulation improved objective measures of gait freezing, with bilateral stimulation more effective than unilateral. During unconstrained walking, Parkinsonian patients who experience gait freezing had reduced step length and increased step length variability compared to patients without gait freezing; however, these deficits were unchanged by pedunculopontine nucleus stimulation. Chronic pedunculopontine nucleus stimulation improved Freezing of Gait Questionnaire scores, reflecting a reduction of the freezing encountered in patients’ usual environments and medication states. This study provides objective, double-blinded evidence that in a specific subgroup of Parkinsonian patients, stimulation of a caudal pedunculopontine nucleus region selectively improves gait freezing but not background deficits in step length. Bilateral stimulation was more effective than unilateral.

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The decision of Applegarth J in Heartwood Architectural & Joinery Pty Ltd v Redchip Lawyers [2009] QSC 195 (27 July 2009) involved a costs order against solicitors personally. This decision is but one of several recent decisions in which the court has been persuaded that the circumstances justified costs orders against legal practitioners on the indemnity basis. These decisions serve as a reminder to practitioners of their disclosure obligations when seeking any interlocutory relief in an ex parte application. These obligations are now clearly set out in r 14.4 of the Legal Profession (Solicitors) Rule 2007 and r 25 of 2007 Barristers Rule. Inexperience or ignorance will not excuse breaches of the duties owed to the court.