in this research, using pyrolysis of phenolic resin in the presence of silicon particles, the sic ceramic composite is formed. the samples were prepared by introducing 30, 35, 40, 45 and 50 wt% of si particles to the phenolic resin. the samples were cured at 180°c then carbonized at 1100°c. the final carbonized c/si composites are hot-pressed at 1500°c in inert atmosphere, which is more than th...

a new method was used to prepare abs/pa6 blends by in situ polymerization and compatibilization method. in this process, ε-caprolactam monomer was polymerized in presence of abs via activated anionic polymerization to produce pa6. the main ingredients of the reaction mixture included: monomer ()ε-caprolactam), catalyst na-caprolactamate), microactivator hdi)( and macro-activator sma)(. then, in...

background and objective: since the advent of mammography screening, ductal carcinoma in situ (dcis) of the breast has been diagnosed increasingly. in contrast to the situation in invasive breast carcinoma, there are only a few reports on androgen receptor (ar) status in dcis and few reports on estrogen (er) and progesterone (pr) receptors. materials and methods: ar expression was examined in 5...

purpose : this study was planned to evaluate the efficacy, safety and complication of photorefractive keratectomy (prk) as a retreatment of residual myopia after previous laser in situ keratomileusis (lasik). methods : in this descriptive study in ophthalmology ward, feiz hospital, isfahan university of medical sciences, iran, with the consideration of inclusion and exclusion criteria, 170 eyes...

the increasing production and use of fossil fuels increase the probability of soil source contamination by oil and petroleum products, and pose a hazard to life. there are over 43,000 chemical contaminated sites in canada and usa, with 2,200 of them classified as high risk. in the us, over $10 billion are spent annually on the cleanup of contaminated sites. the primary objective of this study w...

a fourth-generation ziegler-natta catalyst was prepared to synthesize polypropylene (pp), which was stabilized by in situ polymerization employing lignin as antioxidant. the antioxidant properties of lignin were compared with those of the commercial antioxidant irganox 1010. the presence of lignin in the reaction medium slightly decreased the catalytic activity of the reaction. the isotacticity...