The three-dimensional distribution of melt in partially molten synthetic samples compositionally corresponding to diopside (90 wt.%)–anorthite (10 wt.%) and doped with PbO, WO3, MoO3, or Cs2O to enhance contrast was studied by X-ray computed tomography (CT) with synchrotron radiation. The heavy elements were strongly concentrated in the melt and contributed to an increase of the X-ray linear attenuation coefficient (LAC) of it. PbO was found to be compatible with silicate melt (>20 wt.% in solution) and incompatible with diopside crystals. Other oxides WO3 (∼10 wt.%), MoO3 (∼5 wt.%) and Cs2O (< 5 wt.%) are also soluble only in the melt. Such doping is useful not only for LAC control in X-ray CT measurements, but also for systematic control of the structure (wetting properties, distribution and connectivity) of partial melt. This technique gives basic information for discussion of the 3D distribution of partial melt having different wetting properties. As PbO was most effective in visualization of the diopside–anorthite partially molten system, CT images of the PbO-bearing sample were used for further 3D investigation of distribution. A distribution of dihedral angles at solid-melt-solid triple junctions ranging from 22 to 55° was observed with the 3D data. This range in angle distribution was probably caused by anisotropy of crystals and the result supports the argument that there is some limitation in a theoretical framework of stereology which estimates the 3D structure based on 2D observations. Investigators have begun to apply X-ray CT to the study of the 3D distribution of partial melts in rocks using synchrotron radiation. Our study on the effect of doping is one approach for developing a technique to investigate 3D melt distribution.

This review assesses the circumpolar occurrence of emerged marine macrofossils and sediments from Antarctic coastal areas in relation to Late Quaternary climate changes. Radiocarbon ages of the macrofossils, which are interpreted in view of the complexities of the Antarctic marine radiocarbon reservoir and resolution of this dating technique, show a bimodal distribution. The data indicate that marine species inhabited coastal environments from at least 35 000 to 20 000 yr BP, during Marine Isotope Stage 3 when extensive iceberg calving created a ‘meltwater lid’ over the Southern Ocean. The general absence of these marine species from 20 000 to 8500 yr BP coincides with the subsequent advance of the Antarctic ice sheets during the Last Glacial Maximum. Synchronous re-appearance of the Antarctic marine fossils in emerged beaches around the continent, all of which have Holocene marine-limit elevations an order of magnitude lower than those in the Arctic, reflect minimal isostatic rebound as relative sea-level rise decelerated. Antarctic coastal marine habitat changes around the continent also coincided with increasing sea-ice extent and outlet glacial advances during the mid-Holocene. In view of the diverse environmental changes that occurred around the Earth during this period, it is suggested that Antarctic coastal areas were responding to a mid-Holocene climatic shift associated with the hydrological cycle. This synthesis of Late Quaternary emerged marine deposits demonstrates the application of evaluating circum-Antarctic phenomena from the glacial-terrestrial-marine transition zone.

Ultra thin silicon nitride films have been indispensable in high density memory devices as a dielectric. We investigated the effect of the silicon surface state on initial silicon nitride growth process, we have used X-ray Photoelectron spectrometry (XPS), Secondary ion mass spectrometry(SIMS), and Capacitance-Voltage(C-V) characteristics. The results of our study show that the fluorine on silicon surface influences initial silicon nitride growth. The presence of fluorine delays low pressure chemical vapor deposition(LPCVD) silicon nitride growth as well as restraining native oxide growth at the silicon nitride/silicon substrate interface. We propose that it is a key process of thin dielectric films deposition to control fluorine on silicon surface.