نتایج جستجو برای: freeze thaw cycle
تعداد نتایج: 291199 فیلتر نتایج به سال:
*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 c...
freeze-thaw is one of the most powerful weathering agents that may cause a rapid change in the initial engineering properties of stones, and limit their durability. freeze-thaw induces stress over the pores’ surface of stones. consequently, stone durability is closely related to its engineering and physical properties. the purpose of this study is estimating the engineering properties of deteri...
Background and purpose: Giardia lamblia (G.lamblia) is one of flagellated protozoan pathogens. Giardiasis is the most common human parasite infection in the world, causing a lengthy course of diarrhea. The aim of the present study was to compare five different methods of DNA extraction from G.Lamblia cyst and determining the most efficient DNA extraction method. Materials and methods: This stu...
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...
Freeze-thaw events can affect plant hydraulics by inducing embolism. This study analyzed the effect of temperature during the freezing process on hydraulic conductivity and ultrasonic emissions (UE). Stems of 10 angiosperms were dehydrated to a water potential at 12% percentage loss of hydraulic conductivity (PLC) and exposed to freeze-thaw cycles. The minimal temperature of the frost cycle cor...
BACKGROUND: Freezing is a common way and one of the best methods of seafood preservation for long periods of time; however, the freeze thawing process may influence the quality of food. OBJECTIVES: Oxidation and denaturation of proteins, sublimation and recrystallization of ice crystals can cause changes in the quality of the frozen products. This study was aimed to evaluate the effect of three...
background: freezing is a common way and one of the best methods of seafood preservation for long periods of time; however, the freeze thawing process may influence the quality of food. objectives: oxidation and denaturation of proteins, sublimation and recrystallization of ice crystals can cause changes in the quality of the frozen products. this study was aimed to evaluate the effect of three...
The stability of serum specimens collected for cellulose acetate electrophoresis of lipoproteins has been studied for each of the hyperlipoproteinemia phenotypes. In general, samples kept at room temperature for three days are still suitable for analysis. On longer standing, artifacts can cause misinterpretation of strips, or render them completely unreadable. If specimens are stored at refrige...
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 con...
Cytokines are a group of peptides which form a sophisticated network to modulate multiple cellular events. Within such a network, and through complex feedback mechanisms, cytokine functions are largely interdependent and closely associated with a number of pathological processes. In the present study, the EVIDENCE 180 system was used to study the ...
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