An analytical treatment of the electron screening effect within an active-electron model is given for positronium formation from helium atoms. A first-order distorted wave approximation with correct boundary conditions is ...

The Miocene pyroxene andesite lava flows are exposed in southeastern edge of Urumieh Dokhtar Magmatic assemblage in Iran. The hypocrystalline andesite in parts contain conspicuous co-magmatic igneous enclaves which are ...

As a tool for exploration of concealed coal seams by modern techniques, determination of the depth of erosion of coal seams with reference to the surface of angular unconformity underlying the remnants of a key bed is ...

V2O5/SiO2 nanoparticles was prepared via an one-pot sol gel method from vanadyl- acetylacetonate and tetraethylorthosilicate in refluxing MeOH, followed by calcination at 700 °C for 2 hours. The resultant nanoparticles was ...