地震発生帯における深部掘削孔を用いた長期計測

Large earthquakes occur frequently in subduction zones. Most earthquakes are generated in the seismogenic zone, a fairly limited area confined to the shallower regions of the subduction plate boundary. To understand the processes of earthquake generation, it is essential to monitor the physical and mechanical properties of the seismogenic zone over long periods. At present, there are no deep borehole observations of the seismogenic zone more than 3km below seafloor, because it has, until now, been impossible to penetrate to such depths below the sea floor. The Integrated Ocean Drilling Program (IODP), scheduled to begin in 2003, plans to drill boreholes beneath the ocean floor using a multiple-drilling platform operation. The IODP riser-quipped drilling ship (Chikyu) enables the emplacement of boreholes up to 0km beneath the ocean floor, and will provide opportunities to conduct long-term deep borehole observations in the seismogenic zone. Long-term borehole observations in the seismogenic zone are expected to require the development of advanced sampling, monitoring, and recording technology. Here, we discuss the scientific objectives, engineering and technical challenges, and experimental design for a deep borehole, long-term deepborehole monitoring system aimed at understanding the processes of earthquake generation in the seismogenic zone of subduction plate boundaries. We focus specifically on the relationships between environmental conditions in the deep subsurface, details of monitoring and recording, and design and implementation of scientific tools and programs

Expression, crystallization and preliminary X-ray diffraction analysis of human paired Ig-like type 2 receptor α (PILRα)

Human paired Ig-like type 2 receptor α (PILRα) has been expressed, purified and crystallized. A diffraction data set has been collected to 1.3 Å resolution

A neutron crystallographic analysis of T6 porcine insulin at 2.1 Å resolution

The charge balance and hydrogen-bonding network at the core of the insulin T6 hexamer have been investigated by neutron diffraction analysis at 2.1 Å resolution

Structure Analysis and Derivation of Deformed Electron Density Distribution of Polydiacetylene Giant Single Crystal by the Combination of X‑ray and Neutron Diffraction Data

The crystal structure of polydiacetylene giant single crystal has been analyzed on the basis of the two different methods of wide-angle neutron diffraction and X-ray diffraction. The X-ray result gives us the total electron density distribution [<b>ρ</b>(<b>x</b>)] of polymer chain. The neutron result tells the positions of atomic nuclei, which can allow us to speculate the electron density distributions [<b>ρ</b>₀(<b>x</b>)] around the nonbonded isolated atoms. As a result, the so-called bonded (or deformed) electron density Δρ­(<b>x</b>) [≡ ρ­(<b>x</b>) – ρ₀(<b>x</b>) = ρ_X(<b>x</b>) – ρ_N(<b>x</b>)], i.e., the electron density distribution due to the conjugation among the covalently bonded atoms along the polymer chain, can be estimated using the two information obtained by the X-ray and neutron data analyses (the so-called X-ray–neutron subtraction (X<i>–</i>N) method). The present report is the first example of the application of X–N method to the synthetic polymer species. The Δρ­(<b>x</b>) derived for polydiacetylene was found similar to that of the low-molecular-weight model compound having the similar electronically conjugated chemical formula. The Δρ­(<b>x</b>) was calculated by the density functional theory, which was in a good agreement with the experimental result qualitatively