نتایج جستجو برای: freezing and thaw cycles
تعداد نتایج: 16838989 فیلتر نتایج به سال:
background: leptin and its receptor are present in spermatozoa; however, the role of leptin in sperm function is still controversial. our present study aimed at demonstrating the effect of cryopreservation on sperm dna fragmentation (dnaf) and investigating the possible effects of sperm capacitation techniques and leptin in vitro incubation on frozen-thawed sperm dnaf and oxidative stress. meth...
The migration and transformation of dissolved organic matter during the freezing processes of water.
This study investigated the partitioning behavior of dissolved organic matter (DOM) in liquid and ice phases, as well as the changes in the optical properties and chlorine reactivity of DOM during the freezing processes of water. DOM was rejected from the ice phase and accumulated in the remaining liquid phase during water freezing. Moreover, the decrease in freezing temperature, as well as the...
Abstract The Mu Us Desert in China is significantly affected by seasonal freeze–thaw processes. In order to evaluate the adaptation potential of reconstituted soil with different proportions feldspathic sandstone and sand extreme environment, laboratory simulation freeze-thaw experiments was conducted study characteristics C N under conditions. results showed that content organic matter reached...
Little information is available about the precise mechanisms and determinants of freeze resistance in baker's yeast, Saccharomyces cerevisiae. Genomewide gene expression analysis and Northern analysis of different freeze-resistant and freeze-sensitive strains have now revealed a correlation between freeze resistance and the aquaporin genes AQY1 and AQY2. Deletion of these genes in a laboratory ...
The chloride diffusion of marine high-performance concrete under a couple actions, flexural load and freezing–thawing, was investigated by fast freezing thawing test in NaCl solution. Concrete specimens 100 × 515 mm were tested bending 300 freeze–thaw cycles the stress levels 15%, 30%, 50% ultimate fracture modulus. change microstructure analyzed SEM MIP. results indicated that coefficient coup...
In the present study, motility, ultrastructure and fertilization capacity of fresh and cryopreserved striped bass spermatozoa were investigated in order to evaluate semen dilution ratio, freezing rate and cryomedia. Four dilution ratios (semen/cryomedia), and four freezing rates were evaluated on the basis of post-thaw sperm motility. The dilution ratio of 1:3 yielded the highest (P < 0.05) pos...
Winter warming and its accompanying predicted decrease in snow pack for northern temperate regions may increase frost damage to plants induced by an increase in freeze-thaw cycles (FTCs) due to reduced insulation. FTC frequency, minimum temperature during freezing and pre-existing local adaptations potentially all influence site-specific plant responses to future climatic changes. Within a cham...
Concern over nonpoint source P losses from agricultural lands to surface waters in frigid climates has focused attention on the role of freezing and thawing on P loss from catch crops (cover crops). This study evaluated the effect of freezing and thawing on the fate of P in bare soils, soils mixed with dairy manure, and soils with an established catch crop of annual ryegrass (Lolium multiflorum...
The first and basic cause of the failure of concrete is repeated freezing (thawing) of moisture contained in the pores, microcracks, and cavities of the concrete. On transition to ice, water existing in the free state in cracks increases in volume, expanding the recess in which freezing occurs. A reduction in strength below the initial value is to be expected and further cycle of freezing and t...
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