نتایج جستجو برای: Freeze-thaw cycle
تعداد نتایج: 291199 فیلتر نتایج به سال:
Natural and artificial materials including rocks and cement-based materials such as concrete and cement mortar are affected both physically and chemically by various natural factors known as weathering factors. The freeze-thaw process, as a weathering factor, considerably affects the properties of rocks and concrete. Therefore, the effect of the freeze-thaw process on the physical and mechanica...
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...
The cold climate is a favorable parameter for the development of tension cracks and decrease of rock brittleness. Therefore, this paper attempts to investigate the Hamekasi porous limestone in order to predict the brittleness indices during freeze-thaw cycles. The freeze–thaw test was executed for one cycle including 16 h of freezing, and 8 h of thawing. The geo mechanical properties and brittl...
Liquid water produced in a polymer electrolyte membrane fuel cell experiences a freeze/thaw cycle when the cell is switched off and on while operating at ambient temperatures below freezing. This freeze/thaw cycle permanently deforms the polymer electrolyte membrane fuel cell capillary structures and reduces both the cell life and its ability to generate electric power. The X-ray tomography fac...
Histology and transmission electron microscopy studies were carried out on buffalo muscles that were subjected to repeated freeze-thaw cycles at -10 and -18°C. In the first freeze thaw cycle (-10°C) structures of muscle showed slight change and closely resembled to those of normal muscle. There were frequent gaps in the half way across the fibres and some cracks in individual fibre were also no...
the cold climate is a favorable parameter for the development of tension cracks and decrease of rock brittleness. therefore, this paper attempts to investigate the hamekasi porous limestone in order to predict the brittleness indices during freeze-thaw cycles. the freeze–thaw test was executed for one cycle including 16 h of freezing, and 8 h of thawing. the geo mechanical properties and brittl...
Soft tissue allografts, such as the bone-patellar tendon-bone (BPTB) graft, have been frequently used for anterior cruciate ligament (ACL) reconstruction. As allografts are subjected to freezing and thawing for multiple cycles, the objective of this study was to measure the changes of the biomechanical properties of the human BPTB allograft after 4 and 8 freeze-thaw cycles in comparison to a si...
This study was performed to explore the deterioration of physicochemical quality of beef hind limb during frozen storage at -20℃, affected by repeated freeze-thaw cycles. The effects of three successive freeze-thaw cycles on beef hind limb were investigated comparing with unfrozen beef muscle for 80 d by keeping at -20±1℃. The freeze-thaw cycles were subjected to three thawing methods and carri...
BACKGROUND Analysis of fresh specimens in research studies is ideal; however, it is often necessary to freeze samples for evaluation at a later time. Limited evaluation of the effect of freeze-thawing of tendon tissue samples on inherent magnetic resonance imaging (MRI) parameters, such as ultrashort echo time (UTE) T2* values, have been performed to date. METHODS This study performed UTE MRI...
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...
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