نتایج جستجو برای: freeze and thaw test
تعداد نتایج: 16905035 فیلتر نتایج به سال:
According to standards, the durability performance of fiber-cement sheets must be evaluated by comparing the modulus of rupture (MOR) before and after durability tests (freeze-thaw, soak-dry, and warm water) are completed. This paper investigated the MOR of two different fiber-cement sheets samples before and after durability tests as well as its ductility and toughness. Results showed no signi...
Sealers are used to enhance concrete durability through their ability to prevent moisture penetration and chloride intrusion, consequently improving the freeze-thaw performance of the concrete and preventing corrosion of the steel reinforcement, respectively. This paper summarizes three years of comprehensive field and laboratory investigations which were undertaken at the University of Manitob...
A novel sensor fusion algorithm for retrieving the freeze/thaw state from scatterometer data is presented: it is based on a probabilistic model, a variant of the Hidden Markov model, and it computes the probability that the landscape is frozen, thawed, or thawing for each day. By combining Ku and C band scatterometer data, the distinct backscattering properties of snow, soil and vegetation at t...
Results: The experiment results indicate that the type of recycled aggregate and its replacement ratio have significant effects on the freezethaw performance. The cubic compressive strength of recycled aggregate concrete is overall slightly lower than that of normal concrete. After 100 freeze-thaw cycles, the compressive strength decreases and the reduction extent increases with increasing repl...
*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...
The effects of freeze/thaw (F/T) cycling on the structure of dry Nafion® membranes were investigated using positron annihilation lifetime spectroscopy (PALS). The method correlates the lifetime and relative intensity of positrons (anti-electrons) annihilating in the open-volume voids of the membrane with void size and void volume fraction. The results, though still preliminary, show freeze/thaw...
We evaluated the effects of time, temperature, freezing, and thawing on the cerebrospinal fluid viral load by using the Roche AMPLICOR HIV-1 MONITOR test, version 1.5 (ultrasensitive). While a statistically significant decrease from the baseline was observed at 24 h, but not at 6 or 12 h, and with one freeze-thaw cycle, all changes were within the range of intra-assay variability.
Complete closure of retinal neovascularisation due to proliferative sickle cell retinopathy was achieved in 28 'sea fans' (areas of neovascularisation) in 9 eyes of 9 patients by means of a triple freeze-thaw technique. However, 2 eyes developed subsequent rhegmatogenous retinal detachments, presumably related to vitreous traction on necrotic retina. We therefore recommend photocoagulation as...
The effect of adding xanthan gum and locust bean gum at low concentrations (0.15% w/w) on the freeze/ thaw stability of white sauces prepared with native starches from four different sources (corn, waxy corn, potato, and rice) was investigated. Linear viscoelastic properties were taken as structural indicators and these and syneresis as indicators of the freeze/thaw stability of the sauces. The...
Polyphenoloxidase (PPO), protease activities, melanosis and exudate loss of pre-cooked Pacific white shrimp (Litopenaeus vannamei) subjected to multiple freeze-thaw cycles (1, 3 and 5 cycles) using different thawing methods were studied. PPO and protease activities increased as freeze-thaw cycles increased (p < 0.05). Thawing using running tap water resulted in the higher increases in both PPO ...
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