scholarly journals Characterisation of Phytolith Production and Their Taxonomic Use among Five Species of Aristida

Author(s):  
PI. Jattisha ◽  

Phytoliths are amorphous silicon dioxide depositions in and around the cells of certain plants. Phytoliths of Poaceae are of great importance in the field of taxonomy and Archeology. Present study confirms the use of phytolith characters in the delimitation of Aristida species. Five species of Aristida were included in the study. Various characters like presence or absence of prickle hairs, nature of margins in lobate phytoliths, shank length in relation to the length of lobes etc. proved to be promising characters in the delimitation of the taxa. A taxonomic key to the identification of species is also provided.

Author(s):  
И.П. Щербаков ◽  
А.Е. Чмель

AbstractThe introduction of Si^+ ions and ions of other elements into amorphous silicon dioxide during their interaction causes damage to the structural bonds, which is observed in the vibrational spectral bands. Pure SiO_2 has no optical transitions but the bands of induced point defects appear in the photoluminescence spectrum when ions/neutrons are introduced. The generation of photoluminescence-active defects by fluxes of Ar^+ ion and thermal neutrons is compared. It is shown that the nature of damage to the structure is associated with both the specifics of the synthesis/processing of the material and the features of the interaction between the substance and ions (atomic collisions) and neutrons (collisions with atomic nuclei).


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