(Table 1) Composition of volcanic glasses from the East Scotia Ridge

New U-series isotope data for lavas from the East Scotia backarc spreading center span a large range in (230Th/232Th) and (238U/232Th). Most of the backarc lavas have (238U/230Th) < 1, similar to the composition of mid-oceanic-ridge basalts (MORB). Lavas from two segments have (238U/230Th) > 1 and are enriched in fluid-mobile elements, implying a recent addition of a U-rich slab-derived component. The data from one segment suggest an influence from an aqueous fluid from altered MORB, whereas samples from the other slab-influenced segment show addition of a sediment melt. The slab-influenced samples form a distinct trend in the equiline diagram between aqueous fluid and sediment melt that is suggested to be a mixing line rather than an isochron.

Chemical composition of volcanic glasses from bottom sediments of the Transpacific profile

Lithofacial types of sediments formed in certain geographic and physical-chemical conditions of the Pacific Ocean are distinguished and characterized. It is shown that the regular change of bottom sediment types forming a genetic series from the coast to the pelagic zone clearly demonstrates a leading role of biogenic-terrigenous sedimentation in their formation. In the pelagic zone of the ocean erosion of islands and seamounts, basalt volcanism of anticlinal uplifts, as well as exhalative contribution play some role in addition to the main source of terrigenous and pyroclastic material from continents. These sources do not change, but only complicate terrigenous sedimentation in the studied area of the ocean.

Comparison of adhesion layers of gold on silicate glasses for SERS detection

Gold is one of the most widely used metals for building up plasmonic devices. Although slightly less efficient than silver for producing sharp resonance, its chemical properties make it one of the best choices for designing sensors. Sticking gold on a silicate glass substrate requires an adhesion layer, whose effect has to be taken into account. Traditionally, metals (Cr or Ti) or dielectric materials (TiO2 or Cr2O3 ) are deposited between the glass and the nanoparticle. Recently, indium tin oxide and (3-mercaptopropyl)trimethoxysilane (MPTMS) were used as a new adhesion layer. The aim of this work is to compare these six adhesion layers for surface- enhanced Raman scattering sensors by numerical modeling. The near-field and the far-field optical responses of gold nanocylinders on the different adhesion layers are then calculated. It is shown that MPTMS leads to the highest field enhancement, slightly larger than other dielectric materials. We attributed this effect to the lower refractive index of MPTMS compared with the others.