background: screen time (st), including watching television and playing electronic games are the leading cause of a growing obesity epidemic. this study aimed to evaluate st and its association with physical activity, overweight and socioeconomic status (ses) in children 10 to 12 years of age in sanandaj.   methods: this study was designed as a cross-sectional study, which was conducted in sana...

it is always attempted to reduce the costs of comminution in mineral processing plants. one of thedifficulties in size reduction section is not to be designed properly. the key factor to design size reductionunits such as crushers and grinding mills, is ore’s work index. the work index, wi, presents the oregrindability, and is used in bond formula to calculate the required energy. bond has defi...