Complete agreement of the post-spinel transition with the 660-km seismic discontinuity.

The 660-km seismic discontinuity, which is a significant structure in the Earth's mantle, is generally interpreted as the post-spinel transition, as indicated by the decomposition of ringwoodite to bridgmanite + ferropericlase. All precise high-pressure and high-temperature experiments nevertheless report 0.5-2 GPa lower transition pressures than those expected at the discontinuity depth (i.

A nearly water-saturated mantle transition zone inferred from mineral viscosity.

An open question for solid-earth scientists is the amount of water in Earth's interior. The uppermost mantle and lower mantle contain little water because their dominant minerals, olivine and bridgmanite, have limited water storage capacity. In contrast, the mantle transition zone (MTZ) at a depth of 410 to 660 km is considered to be a potential water reservoir because its dominant minerals, wadsleyite and ringwoodite, can contain large amounts of water [up to 3 weight % (wt %)].

Putting pressure on aromaticity along with in situ experimental electron density of a molecular crystal.

When pressure is applied, the molecules inside a crystal undergo significant changes of their stereoelectronic properties. The most interesting are those enhancing the reactivity of systems that would be otherwise rather inert at ambient conditions. Before a reaction can occur, however, a molecule must be activated, which means destabilized.

Generation of pressures over 40 GPa using Kawai-type multi-anvil press with tungsten carbide anvils.

We have generated over 40 GPa pressures, namely, 43 and 44 GPa, at ambient temperature and 2000 K, respectively, using Kawai-type multi-anvil presses (KMAP) with tungsten carbide anvils for the first time. These high-pressure generations were achieved by combining the following pressure-generation techniques: (1) precisely aligned guide block systems, (2) high hardness of tungsten carbide, (3) tapering of second-stage anvil faces, (4) materials with high bulk modulus in a high-pressure cell, and (5) high heating efficiency.

Elasticity of Ferropericlase across the Spin Crossover in the Earth's Lower Mantle.

Knowing the elasticity of ferropericlase across the spin transition can help explain seismic and mineralogical models of the lower-mantle including the origin of seismic heterogeneities in the middle to lowermost parts of the lower mantle. However, the effects of spin transition on full elastic constants of ferropericlase remain experimentally controversial due to technical challenges in directly measuring sound velocities under lower-mantle conditions. Here we have reliably measured both VP and VS of a single-crystal ferropericlase ((Mg0.

Carbon-depleted outer core revealed by sound velocity measurements of liquid iron-carbon alloy.

The relative abundance of light elements in the Earth's core has long been controversial. Recently, the presence of carbon in the core has been emphasized, because the density and sound velocities of the inner core may be consistent with solid Fe7C3. Here we report the longitudinal wave velocity of liquid Fe84C16 up to 70 GPa based on inelastic X-ray scattering measurements.

Crystal structure of post-perovskite-type CaIrO3 reinvestigated: new insights into atomic thermal vibration behaviors.

Single crystals of the title compound, the post-perovskite-type CaIrO3 [calcium iridium(IV) trioxide], have been grown from a CaCl2 flux at atmospheric pressure. The crystal structure consists of an alternate stacking of IrO6 octa-hedral layers and CaO8 hendeca-hedral layers along [010]. Chains formed by edge-sharing of IrO6 octa-hedra (point-group symmetry 2/m.

P-ρ-T measurements of H2O up to 260 GPa under laser-driven shock loading.

Pressure, density, and temperature data for H2O were obtained up to 260 GPa by using laser-driven shock compression technique. The shock compression technique combined with the diamond anvil cell was used to assess the equation of state models for the P-ρ-T conditions for both the principal Hugoniot and the off-Hugoniot states. The contrast between the models allowed for a clear assessment of the equation of state models.

Elastic anisotropy of experimental analogues of perovskite and post-perovskite help to interpret D'' diversity.

Recent studies show that the D'' layer, just above the Earth's core-mantle boundary, is composed of MgSiO3 post-perovskite and has significant lateral inhomogeneity. Here we consider the D'' diversity as related to the single-crystal elasticity of the post-perovskite phase. We measure the single-crystal elasticity of the perovskite Pbnm-CaIrO3 and post-perovskite Cmcm-CaIrO3 using inelastic X-ray scattering.

Genetic delineation between and within the widespread coccolithophore morpho-species Emiliania huxleyi and Gephyrocapsa oceanica (Haptophyta).

Emiliania huxleyi and Gephyrocapsa oceanica are abundant coccolithophore morpho-species that play key roles in ocean carbon cycling due to their importance as both primary producers and cal-cifiers. Global change processes such as ocean acidification impact these key calcifying species. The physiology of E.

Discovery of an endosymbiotic nitrogen-fixing cyanobacterium UCYN-A in Braarudosphaera bigelowii (Prymnesiophyceae).

Braarudosphaera bigelowii (Prymnesiophyceae) is a coastal coccolithophore with a long fossil record, extending back to the late Cretaceous (ca. 100 Ma). A recent study revealed close phylogenetic relationships between B.

Determination of 17O-excess of terrestrial silicate/oxide minerals with respect to Vienna Standard Mean Ocean Water (VSMOW).

Rationale: Oxygen triple isotope compositions give key information for understanding physical processes during isotopic fractionation between the geo-, hydro-, bio-, and atmosphere. For detailed discussion of these topics, it is necessary to determine precise (17)O-excess values of terrestrial silicate/oxide minerals with respect to Vienna Standard Mean Ocean Water (VSMOW).

Methods: Water was fluorinated in an electrically heated Ni-metal tube into which water and BrF(5) were loaded for the quantitative extraction of oxygen.

Structural characterization of moganite-type AlPO4 by NMR and powder X-ray diffraction.

Structural characterization of a new high-pressure AlPO(4) phase synthesized at 5 GPa and 1500 °C is reported. The phase is monoclinic (P2/a) with a = 8.7437(1) Å, b = 4.

Space environment of an asteroid preserved on micrograins returned by the Hayabusa spacecraft.

Records of micrometeorite collisions at down to submicron scales were discovered on dust grains recovered from near-Earth asteroid 25143 (Itokawa). Because the grains were sampled from very near the surface of the asteroid, by the Hayabusa spacecraft, their surfaces reflect the low-gravity space environment influencing the physical nature of the asteroid exterior. The space environment was examined by description of grain surfaces and asteroidal scenes were reconstructed.

Structures of two new high-pressure forms of AlPO4 by X-ray powder diffraction and NMR spectroscopy.

The crystal structures of two new high-pressure AlPO(4) phases are reported. One phase synthesized at 6 GPa and 1523 K is triclinic (P1) whilst the other phase synthesized at 7 GPa and 1773 K is monoclinic (P2(1)/c). (31)P MAS (magic-angle spinning) NMR suggests three tetrahedral P sites with equal abundance in both phases.

Determination of J coupling constants between spin-1/2 and quadrupolar nuclei in inorganic solids from spin echo and refocused INEPT experiments: a case study on AlPO₄ berlinite.

A systematic study utilizing rotor-synchronized homonuclear ((31)P, (27)Al) and heteronuclear ({(31)P}(27)Al and {(27)Al}(31)P) spin echo, and {(27)Al}(31)P refocused INEPT experiments (employing soft pulses for selective excitation of the central transition for the quadrupolar (27)Al (I=5/2)) have been performed on AlPO(4) berlinite at 30 kHz MAS to better understand the J modulation behavior involving half-integer quadrupolar nuclei in solid materials with framework structure. Analyses of the J modulation on either the (27)Al or (31)P coherence in both the {(31)P}(27)Al and {(27)Al}(31)P spin echo experiments, and both periods of the refocused INEPT experiment yield consistent results for the (2)J(AlP) (Al-O-P) coupling constant (ca. 25 Hz).

Chemical separation and mass spectrometry of Cr, Fe, Ni, Zn, and Cu in terrestrial and extraterrestrial materials using thermal ionization mass spectrometry.

A sequential chemical separation technique for Cr, Fe, Ni, Zn, and Cu in terrestrial and extraterrestrial silicate rocks was developed for precise and accurate determination of elemental concentration by the isotope dilution method (ID). The technique uses a combination of cation-anion exchange chromatography and Eichrom nickel specific resin. The method was tested using a variety of matrixes including bulk meteorite (Allende), terrestrial peridotite (JP-1), and basalt (JB-1b).

Precise elemental and isotopic analyses in silicate samples employing ICP-MS: application of hydrofluoric acid solution and analytical techniques.

In this review, a new classification of elements based on behavior in hydrofluoric acid (HF) solution is presented for the precise quantitative analysis of each element by inductively coupled plasma mass spectrometry (ICP-MS). The elements are divided into 7 groups: (1) "fluorophile" elements; (2) insoluble fluoride-forming elements; (3) "bromophile" or "iodophile" elements; (4) "oxophile" elements; (5) "aquaphile" elements; (6) bare cation elements; and (7) other elements. Especially, the importance of fluorophile and insoluble fluoride-forming elements in elemental analysis is described.

Accumulation of radium in ferruginous protein bodies formed in lung tissue: association of resulting radiation hotspots with malignant mesothelioma and other malignancies.

While exposure to fibers and particles has been proposed to be associated with several different lung malignancies including mesothelioma, the mechanism for the carcinogenesis is not fully understood. Along with mineralogical observation, we have analyzed forty-four major and trace elements in extracted asbestos bodies (fibers and proteins attached to them) with coexisting fiber-free ferruginous protein bodies from extirpative lungs of individuals with malignant mesothelioma. These observations together with patients' characteristics suggest that inhaled iron-rich asbestos fibers and dust particles, and excess iron deposited by continuous cigarette smoking would induce ferruginous protein body formation resulting in ferritin aggregates in lung tissue.

Boron-doped diamond heater and its application to large-volume, high-pressure, and high-temperature experiments.

A temperature of 3500 degrees C was generated using a diamond resistance heater in a large-volume Kawai-type high-pressure apparatus. Re and LaCrO(3) have conventionally been used for heaters in high-pressure studies but they cannot generate temperatures higher than 2900 degrees C and make in situ x-ray observations difficult due to their high x-ray absorption. Using a boron-doped diamond heater overcomes these problems and achieves stable temperature generation for pressure over 10 GPa.

Precise determination of elastic constants by high-resolution inelastic X-ray scattering.

Inelastic X-ray scattering (IXS) measurements have been performed on an MgO single crystal in order to evaluate IXS as a methodology for accurate and precise determination of elastic constants and sound velocities. By performing the IXS experiment using a 12-analyzer array, the complete set of single-crystal elastic constants of MgO were determined to a precision better than 0.8% (sound velocities to better than 0.

Local structure of magnesium in silicate glasses: a 25Mg 3QMAS NMR study.

We have reported the 25Mg triple-quantum magic-angle spinning (3QMAS) NMR spectra of silicate glasses. The two-dimensional spectra suggest that the magnesium ions in MgSiO3, CaMgSi2O6, Ca2MgSi2O7, Mg3Al2Si3O12, and Li2MgSi2O6 glasses are mainly in octahedral environments, although in Na2MgSi2O6, K2MgSi2O6, and K2MgSi5O12 glasses they form tetrahedral species. We discussed the coordination environments of Mg based on the field strength of competing Mg2+, Ca2+, Na+, K+, and Li+ cations, and convincingly demonstrated that there is a correlation between them.

Dry mantle transition zone inferred from the conductivity of wadsleyite and ringwoodite.

The Earth's mantle transition zone could potentially store a large amount of water, as the minerals wadsleyite and ringwoodite incorporate a significant amount of water in their crystal structure. The water content in the transition zone can be estimated from the electrical conductivities of hydrous wadsleyite and ringwoodite, although such estimates depend on accurate knowledge of the two conduction mechanisms in these minerals (small polaron and proton conductions), which early studies have failed to distinguish between. Here we report the electrical conductivity of these two minerals obtained by high-pressure multi-anvil experiments.

High-pressure delta-Al(OH)3 and delta-AlOOH phases and isostructural hydroxides/oxyhydroxides: new structural insights from high-resolution 1H and 27Al NMR.

In order to shed light on the proton distributions and order/disorder in high-pressure delta-Al(OH)3 and delta-AlOOH phases, two-dimensional, high-resolution 1H CRAMPS (FSLG)-MAS NMR and 27Al 3QMAS NMR spectra have been obtained. For delta-Al(OH)3, the 1H CRAMPS-MAS NMR revealed two peaks with an intensity ratio close to 2:1. The 27Al MAS and 3QMAS NMR suggest a single Al site with a well-defined local structure.