Earthquakes and plastic deformation of anhydrous slab mantle in double Wadati-Benioff zones

International audienceDouble Wadati-Benioff seismic zones (DSZ) with two parallel planes of seismicity separated by 15-30 km are a global feature of subduction zones in the 50-200 km depth range. Upper plane seismicity is generally attributed to dehydration of the oceanic crust but the origin of the lower seismicity plane is debated. Serpentine or hydrous-phase dehydration embrittlement is a commonly advocated mechanism that implies significant slab mantle hydration. High-resolution seismic tomography revealed low seismic velocities in the lower seismicity plane that are better explained by seismic anisotropy of anhydrous deformed peridotites than by serpentinization. Earthquakes correlate with anisotropic planar shear zones and favor a shear instability mechanism as the cause of lower plane seismicity without requiring the presence of water in the center of subducting slabs. The contribution of the subducted lithospheric mantle to the water budget of subduction zones is thus likely limited to the first 2-3 kilometers beneath oceanic crust

MEASUREMENT OF FORCES EXERTED DURING SWEEPING IN CURLING

INTRODUCTION: Sweeping is performed to correct the speed or the trajectory of the stone thrown in the game of curling. Curlers are asked to sweep the ice in front of the sliding stone strongly. Therefore we attempted to develop a simple device for measuring the forces exerted on the brush during the sweeping. The present study compared the forces exerted on the brush with the ground reaction forces during the sweeping

Pressure-induced defects in zirconates

Defects, e.g. vacancies and interstitials, play an important role on the physical properties of oxides, especially on their ionic transport. Those defects in oxides are generally controlled and analyzed as functions of dopant concentration, c, temperature, T, and oxygen chemical potential, O2, but not of total pressure, P. This is not surprising given that a molar volume, Vm, of solids is much smaller than that of gas phase by a factor of ≈1/1000. Meanwhile, under high pressure such as several GPa, the effect of total pressure on free energy, i.e. VmP, reaches 20~100 kJ/mol, which is high enough to affect the defect formation and migration in solids. In fact, pressure-induced phenomena are recently of great interest in solid state ionics. In this study, we focus on the pressure effects on the defect formation in some stabilized ZrO2 and acceptor-doped BaZrO3. For Y-stabilized ZrO2, reduction was found to be enhanced under high pressure. Figure 1 shows the lattice constant of 8YSZ electrochemically reduced under high pressure as a function of oxygen deficiency introduced. Under high pressure such as 1 to 6 GPa, 8YSZ was easily reduced even at 3VDC at 500°C. The oxygen deficiency reaches = 0.05. Unlike reduced CeO2 which shows lattice expansion, the reduced 8YSZ shows 0.5% smaller lattice constant. The lattice shrinkage was also confirmed by DFT calculations. This supports that applying high pressure, which in general enhances a reaction with negative volume change, enhances the reducing reaction of cubic ZrO2. Figure 2 shows the temperature dependence of electrical conductivity of reduced 8YSZ. The reduced 8YSZ appears to show mixed ionic and electronic conduction; major carrier is electrons. Acceptor-doped BaZrO3 was also subjected to high pressure on the order of GPa. Their defect equilibrium and proton conductivity will be also discussed. Please click Additional Files below to see the full abstract

Acute- or Subacute-Onset Lung Complications in Treating Patients With Rheumatoid Arthritis

AbstractRheumatoid arthritis (RA) is a common systemic disease that manifests as inflammatory arthritis of multiple joints and produces a wide variety of intrathoracic lesions, including pleural diseases, diffuse interstitial pneumonia, rheumatoid nodules, and airway disease. Patients treated for RA can have associated lung disease that commonly manifests as diffuse interstitial pneumonia, drug-induced lung injury, and infection. The purpose of this pictorial review is to illustrate the radiographic and clinical features of lung complications of acute or subacute onset in patients treated for RA and to show the computed tomography features of these complications