Chemical zoning of garnet is often used to deduce P–T paths of rocks by inverse calculation. To validate the derived P–T paths, it is desired to establish a method to predict the chemical ...compositions of garnet theoretically. This study proposes a new forward calculation of the formation of Mg–Fe–Mn garnet from chlorite, which solves the non-linear simultaneous equations using nested iterative calculations. Growth of garnet consuming chlorite and quartz was modelled in a MnO–FeO–MgO–Al2O3–SiO2–H2O system, using the most recent thermodynamic data for the minerals. The prograde P–T history of the Sambagawa metamorphic belt, SW Japan, was modelled. To reproduce growth zoning, crystallized garnet was removed step by step from the system; perfect diffusion was assumed for chlorite. The proposed model derived the evolution of molar amounts and chemical compositions of Mg–Fe–Mn chlorite and garnet. It successfully reproduced the shape of the observed chemical profile of garnet, although the temperature condition was higher than general observations. The Mn content of the garnet core was generally high, and Mg/Fe ratio always started rising rapidly after Mn was depleted. Thermodynamic properties of minerals, initial chlorite composition, P–T path, H2O partial pressure, and Ca content in garnet were varied to test the behaviour of the system. The properties of Mn phases influenced only the chemical composition of the garnet core. The temperature range in which garnet grew depended on the H2O partial pressure or the Ca content in garnet.
The high frequency dynamics of liquid Te near the melting temperature has been investigated by means of inelastic x-ray scattering measurements. Dynamic structure factors S(Q,E) are obtained at 500, ...650 and 800 deg C. Acoustic excitation is ascertained at each temperature: its Q-dependent phase velocity v(Q) switches from the high frequency value vIXS to the ultrasonic value vs at a certain momentum transfer (Q = Qtrans). With decreasing temperature, both the 'positiveness' () and the effective length () increase, which means that the structural relaxation in liquid Te changes greatly in this temperature region. With the aid of a thermodynamic formulation, we show that this should be seen as evidence of dynamical inhomogeneity: it can be greatly enhanced by the metal -nonmetal transition which occurs in the supercooled region. The dynamical inhomogeneity may be induced by a second critical phenomenon, which is similar to the case for liquid water.
Prograde P–T paths recorded by the chemistry of minerals of subduction‐related metamorphic rocks allow inference of tectonic processes at convergent margins. This paper elucidates the changing P–T ...conditions during garnet growth in pelitic schists of the Sambagawa metamorphic belt, which is a subduction related metamorphic belt in the south‐western part of Japan. Three types of chemical zoning patterns were observed in garnet: Ca‐rich normal zoning, Ca‐poor normal zoning and intrasectoral zoning. Petrological studies indicate that normally‐zoned garnet grains grew keeping surface chemical equilibrium with the matrix, in the stable mineral assemblage of garnet + muscovite + chlorite + plagioclase + paragonite + epidote + quartz ± biotite. Pressure and temperature histories were inversely calculated from the normally‐zoned garnet in this assemblage, applying the differential thermodynamic method (Gibbs' method) with the latest available thermodynamic data set for minerals. The deduced P–T paths indicate slight increase of temperature with increasing pressure throughout garnet growth, having an average dP/dT of 0.4–0.5 GPa/100 °C. Garnet started growing at around 470 °C and 0.6 GPa to achieve the thermal and baric peak condition near the rim (520 °C, 0.9 GPa). The high‐temperature condition at relatively low pressure (for subduction related metamorphism) suggests that heating occurred before or simultaneously with subduction.
Abstract Background Mineral and bone disorder (MBD) is a major complication of chronic kidney disease and remains a major problem even after kidney transplantation. Although early steroid withdrawal ...protocols have beneficial effects on mineral and bone metabolism, they are also associated with significantly increased rates of acute allograft rejection (AR). Recently, patients have been treated with early rapid corticosteroid reduction protocols, but it is still unclear whether these protocols reduce the rate of MBD. The aim of this study was to evaluate the effects of early rapid corticosteroid reduction on MBD after kidney transplantation. Methods We retrospectively evaluated 34 adult kidney transplant recipients who were treated with an early rapid corticosteroid reduction protocol. Glucocorticoid treatment was reduced to methylprednisolone 4 mg/d at 1 month after transplantation. Results The AR rate at 3 years after transplantation was 15%. Bone mineral density was slightly decreased in the femur at 4 months after transplantation but returned to the preoperative level by 24 months after transplantation. There was no significant decrease in the bone mineral density of the lumbar spine during the first year after transplantation. Urinary deoxypyridinoline levels and plasma osteocalcin levels returned to the normal range during the follow-up period. Bone mineral density tended to be lower in female patients than male patients and in patients who underwent long-term pretransplant dialysis than those who did not undergo long-term pretransplant dialysis. Conclusion The present study found that MBD was temporary in kidney transplant recipients who were treated with an early rapid corticosteroid reduction protocol and that these patients did not have an increased AR rate.
Collective dynamics in liquid GeTe was investigated by inelastic x-ray scattering at 2≤Q≤31nm−1. The dynamic structure factor shows clear inelastic excitations. The excitation energies at low Q ...disperse with increasing Q, consistent with the behavior of a longitudinal-acoustic excitation. The dispersion curve has a flat-topped region around the pseudo-Brillouin-zone boundary, similar to what is observed in liquid Bi Inui et al., Phys. Rev. B 92, 054206 (2015). The dynamic structure factor shows a low-frequency excitation, and its coupling with the longitudinal-acoustic mode plays an important role for a flat-topped dispersion. From these results, it is inferred that atomic dynamics in liquid GeTe is strongly affected by a Peierls distortion similar to liquid Bi. By comparing the momentum transfer dependence of the excitation energy and quasielastic linewidth to partial structure factors obtained by our own ab initio molecular dynamics simulation for liquid GeTe, the quasielastic and inelastic components were found to be correlated with Te-Te and Ge-(Ge,Te) partial structure factors, respectively.
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