Abstract

    Binary polymer blend was prepared by mechanical mixing method of unsaturated polyester resin with Nitrile Butadiene Rubber (NBR) with different weight ratios (0, 5, 10 and 15) % of (NBR). Tensile characteristics and wear rates of these blends were studied for all mixing ratios. The microstructure of fracture surfaces of the prepared samples were investigated by optical microscope. The results were showed that strain rates of the resin material increase after blending it with rubber while the ultimate tensile strength and Young’s modulus values of it will decrease. It is also noticed that the wear rate of resin decreases with increasing of (NBR) content.

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Curing of concrete is the maintenance of a satisfactory moisture content and temperature for a
period of time immediately following placing so the desired properties are developed. Accelerated
curing is advantages where early strength gain in concrete is important. The expose of concrete
specimens to the accelerated curing conditions which permit the specimens to develop a significant
portion of their ultimate strength within a period of time (1-2 days), depends on the method of the
curing cycle.Three accelerated curing test methods are adopted in this study. These are warm water,
autogenous and proposed test methods. The results of this study has shown good correlation
between the accelerated strength especially for

Introduction: Streptococcus mutans and lactobacilli are most important bacteria in the pathogenesis of dental caries. Cariogenic microflora has been associated to the primary caregiver transmission and sugary diets.

Aim: This study aimed to relate S. mutans and lactobacilli in the plaque to demographic factors in Iraqi children.

Materials and methods: The study included 135 children aged 3-10 years. Samples of their dental plaque were taken from the upper second primary molars on the buccal surfaces using a clean toothpick. Each sample was stored in 1 ml of n

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