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Abstract Background The relationship between Mg (magnesium), Cu (copper), and K (potassium) intakes and the risk of rheumatoid arthritis (RA) remains limited. The aim of present study was to examine the associations between Mg, Cu and K intakes with RA. Methods Using data from the National Health and Nutrition Examination Survey (NHANES) 2003–2018, we examined the association between Mg, Cu and K intakes and the risk of RA among US adults. After adjustment for age, sex, race, BMI, educational level, smoking history, alcohol consumption, family Poverty Income Ratio (PIR), diabetes and total daily energy intake, logistic regression models and smooth curve fitting were applied to examine the associations of Mg, Cu and K intakes with RA. Results A total of 18,338 participants were included (1,008 participants with RA). The multivariate adjusted ORs (95% CI) of RA were [0.66 (0.51, 0.84)], [0.76 (0.60, 0.97)], and [0.75 (0.58, 0.97)] in the highest versus lowest quartile of magnesium intakes, respectively. A nonlinear association between Cu intakes and RA was found. When Cu intake (ln) was between 0.6–2.2 mg, the risk of RA reduced by 26% for every 1 mg increase of intake in Cu [0.74 (0.58, 0.96)]. Conclusions Higher Mg, Cu and K intakes may be inversely associated with the risk of RA among US adults, and an inverse L-shaped association between dietary Cu and RA was found.

Clinochlore is a major hydrous mineral in subduction zones, and its thermophysical properties at high temperature and pressure are critical to the thermal structures of subduction zones. Here, we used the pulse heating method to measure thermal diffusivity and thermal conductivity of clinochlore at 0.5-4.0 GPa and 298-1373 K. Our results indicate that upon heating, thermal diffusivity and thermal conductivity decrease from ~9.6 x 10-7 m² s-1 to 4.3 x 10-7 m² s-1 and from ~3.5 W m-1 K-1 to 1.9 W m-1 K-1, respectively, before dehydration, but this trend is reversed after dehydration. In general, the pressure derivatives for the thermal transport properties also decrease with temperature before dehydration. Lattice heat transfer is the dominant mechanism before dehydration, but fluid is involved after dehydration. Using our experimental data, we simulated the temperature distribution of subducting slabs containing clinochlore at volume fractions of 0%, 10%, 20%, 50%, and 100%. Our simulations showed that the heat insulation effect caused by the presence of clinochlore could result in an increase in temperature by 30-60 K for the upper part of the subducting slab. [ABSTRACT FROM AUTHOR]

The increased velocity associated with decaying seismicity in the subducting oceanic crust usually has been attributed to its eclogitization. However, the degree of the eclogitization of subducting oceanic crust at depth remains unclear due to the lack of velocity data for eclogite at pressures of >3 GPa. In this study, the P- and S-wave velocities of eclogite aggregates composed of omphacite and garnet (Omp100, Omp80Grt20, and Omp- 50Grt50) were measured simultaneously at pressures of up to 8 GPa using ultrasonic interferometry. The velocities of the eclogite aggregates increased with rising pressure and garnet content. By determining the velocities at different pressures using the finite strain equation, the elastic moduli of the eclogites and their pressure derivatives were determined to be KS0 = 119-134 GPa, KS0‰ = 5.2-5.3, G0 = 73-80 GPa, and G0‰ = 1.5-1.6. The high-wave velocity and low VP/VS ratio of the eclogites, combined with the seismic tomography and seismicity distribution, jointly constrain the depth and composition of eclogitization in the subducted oceanic crust of Northeast Japan, and a new 1-D velocity structure is proposed. We also compiled and calculated the depth of the eclogitization and the garnet content of the subducting oceanic crusts in 27 typical locations around the Pacific Ocean. The depth of the eclogitization was positively correlated with the age of the subduction zone, and the garnet content was estimated to be 12%-32% in our model. [ABSTRACT FROM AUTHOR]

Antigorite dehydration experiments were performed under ambient pressure using a non-isothermal thermogravimetric analysis. Antigorite, with a grain size of 5-10 µm, was analyzed using heating rates of 10, 15, 20, and 25 K/min at temperatures of up to 1260 K. The results show that the progress of the dehydration reaction varies with the heating rate, and the dehydration reaction of antigorite occurs within a temperature range of 800-1050 K. Several models were used to fit the dehydration results, and the double-Gaussian distribution activation energy model (2-DAEM) yielded the best fit to the experimental data. The dehydration kinetics of antigorite follow 2-DAEM, and there is a compensation effect between the pre-exponential factor and the average activation energy. The activation energy of the first step of antigorite dehydration stretches over a wide interval; the second step has a significantly higher activation energy, distributed over a narrower interval. We determined that the release rate of H2O is 8.0x10[sup -5] and 2.1x10-3 m³fluidm³rocks-1 at 893 and 973 K, respectively, which are near the onset temperature for the isothermal dehydration reaction. Our results indicate that antigorite dehydration is fast enough to induce mechanical instabilities that may trigger seismicity in the lower plane of the double seismic zone. [ABSTRACT FROM AUTHOR]

In situ Raman measurements of barite were performed at temperatures in the range of 298-673 K and pressures in the range of 105-1217 MPa using a hydrothermal diamond anvil cell combined with laser Raman spectroscopy. The Raman frequency and the full width at half maximum (FWHM) of the most intense v1 Raman peak for barite as a function of pressure and temperature were obtained. In the experimental P-T ranges, the v1Raman band systematically shifted toward low wavenumbers with increasing pressure and temperature. The positive pressure dependence of v1Raman frequency indicates stress-induced shortening of the S-O bond, whereas the negative temperature dependence shows temperatureinduced expansion of the S-O bond. In contrast, the observed v1Raman band became broadened, which should be attributed to the reduced ordering of molecular structure. Based on the obtained data, the established relationships among the Raman shift or the FWHM, pressure and temperature can be used to obtain good estimates of the internal pressure in natural barite-bearing fluid inclusions or hydrothermal diamond anvil cell. This is a sensitive and reliable approach to the accurate determination of geological pressure. [ABSTRACT FROM AUTHOR]