Viscosity of bridgmanite determined by in situ stress and strain measurements in uniaxial deformation experiments

To understand mantle dynamics, it is important to determine the rheological properties of bridgmanite, the dominant mineral in Earth’s mantle. Nevertheless, experimental data on the viscosity of bridgmanite are quite limited due to experimental difficulties. Here, we report viscosity and deformation mechanism maps of bridgmanite at the uppermost lower mantle conditions obtained through in situ stress-strain measurements of bridgmanite using deformation apparatuses with the Kawai-type cell. Bridgmanite would be the hardest among mantle constituent minerals even under nominally dry conditions in the dislocation creep region, consistent with the observation that the lower mantle is the hardest layer. Deformation mechanism maps of bridgmanite indicate that grain size of bridgmanite and stress conditions at top of the lower mantle would be several millimeters and ~105 Pa to realize viscosity of 1021–22 Pa·s, respectively. This grain size of bridgmanite suggests that the main part of the lower mantle is isolated from the convecting mantle as primordial reservoirs

A Small Tokamak “NOVA II”

A small tokamak, NOVA II, has been designed and constructed. The major radius is 30 cm, the minor radius 6 cm and the maximum toroidal field 15 kG. The device has a removable shell assembly for studying the stabilizing effect of a conductive shell. The basic concept of design and the specifications of the principal components are described. In preliminary experiments, stable discharge was maintained for 15 msec or longer. The electron temperatures measured by diamagnetism and conductivity are both above 100 eV. An electron density of 1-2×10¹³ cm⁻³ was observed by a 6 mm microwave interferometer. Spectroscopy of impurity lines and intensity measurement of hard X-ray radiation are also described

The Association of Triglyceride to High-Density Lipoprotein Cholesterol Ratio with High-Risk Coronary Plaque Characteristics Determined by CT Angiography and Its Risk of Coronary Heart Disease

The triglyceride to high-density lipoprotein cholesterol (TG/HDL-C) ratio is an independent risk index for cardiovascular events. This study aimed to evaluate the association between TG/HDL-C ratio and coronary plaque characteristics as seen on coronary computed tomography angiography (CCTA) and the corresponding increase in the likelihood of cardiovascular events. A total of 935 patients who underwent CCTA for suspected coronary artery disease (CAD) were included. High-risk plaques (HRP) were defined based on three characteristics: positive remodeling, low-density plaques, and spotty calcification. Significant stenosis was defined as luminal narrowing of >70%. Patients with a higher TG/HDL-C ratio showed significantly greater prevalence of HRP and significant stenosis than patients with low TG/HDL-C ratios (p < 0.01). Multivariate logistic analysis demonstrated that the TG/HDL-C ratio was significantly associated with the presence of HRP (p < 0.01) but not with significant coronary stenosis (p = 0.24). During the median follow-up period of 4.1 years, 26 cardiovascular events including cardiovascular death and acute coronary syndrome occurred. The highest TG/HDL-C tertile was associated with cardiovascular events, with the lowest TG/HDL-C tertile as the reference (hazard ratio, 3.75; 95% confidence interval, 1.04-13.50). A high TG/HDL-C ratio is associated with the presence of CCTA-verified HRP, which can lead to cardiovascular events in patients with suspected CAD

Non-B hepatocellular carcinoma: influence of age, sex, alcohol, family clustering, blood transfusion and chronic liver disease.

In 144 cases of hepatocellular carcinoma (HCC), 166 cases of cirrhosis without HCC and 142 cases of chronic hepatitis, we examined HBsAg, anti-HBs and anti-HBc in sera and compared the following factors between hepatitis B virus marker-negative and -positive patients: age, sex, alcohol consumption, family clustering of liver diseases, and histories of blood transfusion and post-transfusion hepatitis. Results of this study demonstrated several distinct differences in clinical backgrounds between non-B (negative for HBsAg, anti-HBs and anti-HBc) and B (positive for HBsAg) patients with HCC. Non-B patients were significantly older, had a lower frequency of familial tendencies for liver diseases, and more frequently had cancers other than HCC in their families. Some of these differences were also observed between non-B and B patients with cirrhosis and chronic hepatitis. Among patients with chronic hepatitis, the non-B patients had received blood transfusion or had post-transfusion hepatitis more frequently than the B patients. However, this difference was not apparent in patients with liver cirrhosis or HCC, suggesting that progression of non-A, non-B post-transfusion hepatitis to cirrhosis and HCC may not be as frequent as progression to chronic hepatitis.</p

Rheology of hexagonal close-packed(hcp) iron

The viscosity of hexagonal close-packed (hcp) Fe is a fundamental property controlling the dynamics of the Earth’s inner core. We studied the rheology of hcp-Fe using high-pressure and -temperature deformation experiments with in situ stress and strain measurements. Experiments were conducted using D111-type and deformation-DIA apparatuses at pressures of 16.3–22.6 GPa, temperatures of 423–923 K, and uniaxial strain rates of 1.52 × 10−6 to 8.81 × 10−5 s−1 in conjunction with synchrotron radiation. Experimental results showed that power-law dislocation creep with a stress exponent of n = 4.0 ± 0.3, activation energy of E* = 240 ± 20 kJ/mol, and activation volume of V* = 1.4 ± 0.2 cm3/mol is dominant deformation mechanism at >∼800 K, whereas a mechanism with power-law breakdown prevails at lower temperatures. An extrapolation of the power-law dislocation creep flow law based on homologous temperature scaling suggests the viscosity of hcp-Fe under inner core conditions is ≥∼1019 Pa s. If this power-law dislocation creep mechanism is assumed to be the dominant mechanism in the Earth’s inner core, the equatorial growth or translation mode mechanism may be the dominant geodynamical mechanism causing the observed inner core structure

A CASE OF CORONAVIRUS DISEASE 2019 COMPLICATED BY VENTILATORASSOCIATED PNEUMONIA, LUNG ABSCESS, AND STAPHYLOCOCCUS AUREUS BACTEREMIA

Complications of healthcare-associated infections have been reported in patients with coronavirus disease 2019 (COVID-19). We encountered a case of ventilator-associated pneumonia and lung abscess, complicated with Staphylococcus aureus bacteremia and multiple abscesses, in a patient with COVID-19. Streptococci and anaerobes were cultured from the sputum, which was considered to be the causative organism of the lung abscess. In the management of severe COVID-19, care should be taken to prevent complications of healthcare-associated infections; when secondary respiratory tract infections are suspected, the presence of lung abscess and anaerobic culture should be considered

Mantle dynamics inferred from the crystallographic preferred orientation of bridgmanite

　Seismic shear wave anisotropy is observed in Earth's uppermost lower mantle around several subducted slabs. The anisotropy caused by the deformation-induced crystallographic preferred orientation (CPO) of bridgmanite (perovskite-structured (Mg,Fe)SiO3) is the most plausible explanation for these seismic observations. However, the rheological properties of bridgmanite are largely unknown. Uniaxial deformation experiments have been carried out to determine the deformation texture of bridgmanite, but the dominant slip system (the slip direction and plane) has not been determined. Here we report the CPO pattern and dominant slip system of bridgmanite under conditions that correspond to the uppermost lower mantle (25 gigapascals and 1,873 kelvin) obtained through simple shear deformation experiments using the Kawai-type deformation-DIA apparatus. The fabrics obtained are characterized by [100] perpendicular to the shear plane and [001] parallel to the shear direction, implying that the dominant slip system of bridgmanite is [001](100). The observed seismic shear- wave anisotropies near several subducted slabs (Tonga-Kermadec, Kurile, Peru and Java) can be explained in terms of the CPO of bridgmanite as induced by mantle flow parallel to the direction of subduction

Structural and functional insights into thermally stable cytochrome c' from a thermophile

Thermophilic Hydrogenophilus thermoluteolus cytochrome c0 (PHCP) exhibits higher thermal stability than a mesophilic counterpart, Allochromatium vinosum cytochrome c0 (AVCP), which has a homo-dimeric structure and ligand-binding ability. To understand the thermal stability mechanism and ligand-binding ability of the thermally stable PHCP protein, the crystal structure of PHCP was first determined. It formed a homo-dimeric structure, the main chain root mean square deviation (rmsd) value between PHCP and AVCP being 0.65 A ° . In the PHCP structure, six specific residues appeared to strengthen the heme-related and subunit–subunit interactions, which were not conserved in the AVCP structure. PHCP variants having altered subunit–subunit interactions were more severely destabilized than ones having altered heme-related interactions. The PHCP structure further revealed a ligand-binding channel and a penta-coordinated heme, as observed in the AVCP protein. A spectroscopic study clearly showed that some ligands were bound to the PHCP protein. It is concluded that the dimeric PHCP from the thermophile is effectively stabilized through heme-related and subunit–subunit interactions with conservation of the ligand-binding ability.This work was performed under the Cooperative Research Program of the “Network Joint Research Center for Materials and Devices”