Sputtering yields exceeding 1000 by 80keV Xe irradiation of Au nanorods

Using experiments and computer simulations, we find that 80 keV Xe ion irradiation of Au nanorods can produce sputtering yields exceeding 1000, which to our knowledge are the highest yields reported for sputtering by single ions in the nuclear collision regime. This value is enhanced by more than an order of magnitude compared to the same irradiation of flat Au surfaces. Using MD simulations, we show that the very high yield can be understood as a combination of enhanced yields due to low incoming angles at the sides of the nanowire, as well as the high surface-to-volume ratio causing enhanced explosive sputtering from heat spikes. We also find, both in experiments and simulations, that channeling has a strong effect on the sputtering yield: if the incoming beam happens to be aligned with a crystal axis of the nanorod, the yield can decrease to about 100

Pattern formation on ion-irradiated Si surface at energies where sputtering is negligible

The effect of low energy irradiation, where the sputtering is imperceptible, has not been deeply studied in the pattern formation. In this work, we want to address this question by analyzing the nanoscale topography formation on a Si surface, which is irradiated at room temperature by Arthorn ions near the displacement threshold energy, for incidence angles ranging from 0 degrees to 85 degrees. The transition from the smooth to ripple patterned surface, i.e., the stability/instability bifurcation angle is observed at 55 degrees, whereas the ripples with their wave-vector is parallel to the ion beam projection in the angular window of 60 degrees-70 degrees, and with 90 degrees rotation with respect to the ion beam projection at the grazing angles of incidence. A similar irradiation setup has been simulated by means of molecular dynamics, which made it possible, first, to quantify the effect of the irradiation in terms of erosion and redistribution using sequential irradiation and, second, to evaluate the ripple wavelength using the crater function formalism. The ripple formation results can be solely attributed to the mass redistribution based mechanism, as erosion due to ion sputtering near or above the threshold energy is practically negligible. Published by AIP Publishing.Peer reviewe

Heating of nuclei with energetic anti-protons

International audienceHigh-energy γ rays associated with the decay of the giant dipole resonance have been measured for two fusion reactions leading to the 140Sm compound nucleus at an excitation energy of 71 MeV. The observed yield increases with the asymmetry in the ratios of the number of neutrons to protons in the entrance channel. This is interpreted as resulting from giant dipole phonons excited at the moment of collision in an N/Z asymmetric reaction

BIOTIC DIVERSITY OF KARELIA: CONDITIONS OF FORMATION, COMMUNITIES AND SPECIES

The monograph generalises vast data characterising the diversity of the biota in Russian Karelia. The data pool includes both materials of long-term studies, and new data collected in 1997–2000 within the Russian-Finnish project “Inventory and studies of biological diversity in Republic of Karelia”. The volume is composed of four interrelated chapters. Chapter one provides a detailed account of the climatic, geological, geomorphological, hydrological and soil conditions in which the regional biota has been forming. Chapter two describes and evaluates the diversity of forest, mire and meadow communities, and the third chapter details the terrestrial biota at the species level (vascular plants, mosses, aphyllophoroid fungi, lichens, mammals, birds, insects). A special section is devoted to the flora and fauna of aquatic ecosystems (algae, zooplankton, periphyton, macrozoobenthos, fishes). Wide use is made of various zoning approaches based on biodiversity-related criteria. Current status of the regional biota, including its diversity in protected areas, is analysed with elements of the human impact assessment. A concise glossary of the terms used is annexed. This is an unprecedentally multi-faceted review, at least for the taiga zone of European Russia. The volume offers extensive reference materials for researchers in a widest range of ecological and biological fields, including graduate and post-graduate students. The monograph is also available in Russian

Enhanced Sputtering Yields from Single-Ion Impacts on Gold Nanorods

Sputtering yields, enhanced by more than an order of magnitude, have been observed for 80 keV Xe ion irradiation of monocrystalline Au nanorods. Yields are in the range 100–1900  atoms/ion compared with values for a flat surface of ≈50. This enhancement results in part from the proximity of collision cascades and ensuing thermal spikes to the nanorod surfaces. Molecular dynamic modeling reveals that the range of incident angles occurring for irradiation of nanorods and the larger number of atoms in “explosively ejected” atomic clusters make a significant contribution to the enhanced yield

Enhanced sputtering yields from single-ion impacts on gold nanorods

Sputtering yields, enhanced by more than an order of magnitude, have been observed for 80 keV Xe ion irradiation of monocrystalline Au nanorods. Yields are in the range 100-1900 atoms/ion compared with values for a flat surface of ≈50. This enhancement results in part from the proximity of collision cascades and ensuing thermal spikes to the nanorod surfaces. Molecular dynamic modeling reveals that the range of incident angles occurring for irradiation of nanorods and the larger number of atoms in ?explosively ejected? atomic clusters make a significant contribution to the enhanced yield

In vitro screening for antitumour activity of Clinopodium vulgare L. (Lamiaceae) extracts.

Aqueous extract of Clinopodium vulgare L. showed strong antitumour activity when tested in vitro on A2058 (human metastatic melanoma), HEp-2 (epidermoid carcinoma, larynx, human) and L5178Y (mouse lymphoma) cell lines-6 h after treatment disintegration of the nuclei and cell lysis started. Applied at a concentration of 80 microg/ml it reduced the cell survival to 1.0, 5.6 and 6.6%, respectively. The concentrations of aqueous extract inhibiting the growth of A2058, HEp-2 and L5178Y cells by 50% (IC50 values) were calculated to be 20, 10 and 17.8 microg/ml respectively. Two groups of active substances were detected: the first one, probably combining glycosides, influenced adhesion, while the second one caused massive cell vacuolisation. The chloroform extract, which contained ursolic acid and gentriacontan had also cytotoxic, however a little bit weaker effect. All changes observed were irreversible