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...

A key challenge in mammalian biology is to understand how rates of transcription and mRNA degradation jointly shape cellular gene expression. Powerful techniques have been developed for measuring these rates either genome-wide or at the single-molecule level, however these techniques are not applicable to assessment of cells within their native tissue microenvironment. Here we describe a techni...

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...

copper matrix composite reinforced by 1wt.% tib2 particles was prepared using in situ reaction of cu-1.4wt.% ti and cu-0.7wt.% b by rapid solidification and subsequent heat treatment for 1-20 hrs at 900ºc. high-resolution transmission electron microscopy (hrtem) characterization showed that primary tib2 particles were formed in liquid copper. heat treatment of as-solidified samples led to the f...

in this work, the potential of auto-ignition of heavy oil during in-situ combustion (isc) process was studied. kinetic studies were carried out using thermo gravimetric analyzer (tga), differential scanning calorimetry (dsc) and accelerating rate calorimetric (arc) techniques. effects of oxygen partial pressure, reservoir pressure and clay on auto ignition condition were investigated on a numbe...