نتایج جستجو برای: freezing and thaw cycles
تعداد نتایج: 16838989 فیلتر نتایج به سال:
STUDY QUESTION What are the clinical efficacy and perinatal outcomes following transfer of vitrified blastocysts compared with transfer of fresh or of slow frozen blastocysts? SUMMARY ANSWER Compared with slow frozen blastocysts, vitrified blastocysts resulted in significantly higher clinical pregnancy and live delivery rates with similar perinatal outcomes at population level. WHAT IS KNOW...
This study tested different concentrations of egg yolk in canine freezing extender void of glycerol, a commonly used cryoprotectant, by examining the motility and morphology throughout the freezing process: initial (baseline after extender added), post-cool (after three hours at 5°C) and post-thaw (after freezing.) Initial values of pH, osmolarity, motility and morphology were obtained for comp...
During normal sample preparation, storage in freezers and subsequent freeze/thaw cycles are commonly introduced. The effect of freeze/thaw cycles on the metabolic profiling of microalgal extracts using HR-MS was investigated. Methanolic extracts of monocultures of Arctic marine diatoms were analyzed immediately after extraction, after seven days of storage at -78 °C (one freeze/thaw cycle), and...
There is much evidence to suggest that the structural and functional integrity of many biochemical materials is unaltered by freezing if the rate of cooling is rapid and the storage temperature low (2-6). Isolated enzymes and mixtures of enzymes and their substrates, after rapid freezing at low temperatures, often retain their activities and in some cases show enhanced activity upon thawing (7-...
Vitrification and slow-freezing methods have been used for the cryopreservation of human pluripotent stem cells (hPSCs). Vitrification requires considerable skill and post-thaw recovery is low. Furthermore, it is not suitable for cryopreservation of large numbers of hPSCs. While slow-freezing methods for hPSCs are easy to perform, they are usually preceded by a complicated cell dissociation pro...
Background: Since the deleterious effects of reactive oxygen species (ROS) during sperm cryopreservation can be overcome by antioxidants, post-thaw human sperm quality may perhaps profit from adding antioxidants to the extender media prior to cryopreservation. This study evaluated the effects of different concentrations of Trolox supplementation to cryo-protective media on post-thaw motility an...
As the name dehydrins implies, these proteins are typically expressed in response to dehydration, which can be caused by drought, osmotic stress, or freezing temperatures.1 In general, dehydrins occur in plants as multi-gene families. Four arabidopsis dehydrins (LTI29, ERD14, COR47 and RAB18) were tested for protection of thylakoid membranes during freeze–thaw cycles in vitro.2,3 The first repo...
Concrete patch repair has long been used to repair the damaged concrete structures. In cold regions, freeze– thaw cycle is one of the major damage factors. Not only the material itself is damaged by freeze–thaw cycles, but also the adhesive interface, which is regarded as the weakest part of composite system, degrades under freeze–thaw cycles. Air entraining agent has long been used to increase...
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 ...
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 thi...
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