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 applied to evaluate the transition amplitude. In the range of impact energy for which the introduced perturbative approach is valid, both the total and differential cross sect...

the effect of european black alder (alnus glutinosa l.) on the contents of carbon and nitrogen,exchangeable base cations, and plant available forms of phosphorus in the reclaimed mine soils formed bywaste deposition from opencast lignite mines was researched in central serbia. it was concluded that thegreatest part of dead organic residues reaching the soil under european black alder monocultur...

phosphorus (p), in the form of phosphate ion (pi), is a vital element contributing in biomolecule structures, metabolic reactions, signaling pathways and energy transfer within the living cells. the objective of the present study was to assess the influence of fungal infection on pi metabolism in compare to the effects of phosphate stress in arabidopsis. quantification of total p contents showe...