In December 2019, coronavirus disease (COVID-19) emerged in Wuhan. However, the characteristics and risk factors associated with disease severity, unimprovement and mortality are unclear and our ...objective is to throw some light on these.
All consecutive patients diagnosed with COVID-19 admitted to the Renmin Hospital of Wuhan University from January 11 to February 6, 2020, were enrolled in this retrospective cohort study.
A total of 663 COVID-19 patients were included in this study. Among these, 247 (37.3%) had at least one kind of chronic disease; 0.5% of the patients (n = 3) were diagnosed with mild COVID-19, while 37.8% (251/663), 47.5% (315/663), and 14.2% (94/663) were in moderate, severe, and critical conditions, respectively. In our hospital, during follow-up 251 of 663 patients (37.9%) improved and 25 patients died, a mortality rate of 3.77%. Older patients (>60 years old) and those with chronic diseases were prone to have a severe to critical COVID-19 condition, to show unimprovement, and to die (p <0.001, <0.001). Multivariate logistic regression analysis identified being male (OR = 0.486, 95%CI 0.311–0.758; p 0.001), having a severe COVID-19 condition (OR = 0.129, 95%CI 0.082–0.201; p <0.001), expectoration (OR = 1.796, 95%CI 1.062–3.036; p 0.029), muscle ache (OR = 0.309, 95%CI 0.153–0.626; p 0.001), and decreased albumin (OR = 1.929, 95%CI 1.199–3.104; p 0.007) as being associated with unimprovement in COVID-19 patients.
Male sex, a severe COVID-19 condition, expectoration, muscle ache, and decreased albumin were independent risk factors which influence the improvement of COVID-19 patients.
Our understanding of when and how humans adapted to living on the Tibetan Plateau at altitudes above 2000 to 3000 meters has been constrained by a paucity of archaeological data. Here we report data ...sets from the northeastern Tibetan Plateau indicating that the first villages were established only by 5200 calendar years before the present (cal yr B.P.). Using these data, we tested the hypothesis that a novel agropastoral economy facilitated year-round living at higher altitudes since 3600 cal yr B.P. This successful subsistence strategy facilitated the adaptation of farmers-herders to the challenges of global temperature decline during the late Holocene.
Understanding the roles of metals and atomic structures in activating various elementary steps of electrocatalytic reactions can help rational design of binary or ternary catalysts for promoting ...activity toward desirable products via favorable pathways. Here we report on a newly developed ternary Au@PtIr core–shell catalyst for ethanol oxidation reaction (EOR) in alkaline solutions, which exhibits an activity enhancement of 6 orders of magnitude compared to AuPtIr alloy catalysts. Analysis of in situ infrared reflection absorption spectra for Au@PtIr and its bimetallic subsets, Au@Pt and PtIr alloy, found that monatomic steps and Au-induced tensile strain on PtIr facilitate C–C bond splitting via ethanol dissociative adsorption and Ir promotes dehydrogenation at low potentials. As evidenced by the CO band being observed only for the PtIr alloy that is rather inactive for ethanol dissociative adsorption, we propose that splitting the C–C bond at the earliest stage of EOR activates a direct 12-electron full oxidation pathway because hydrogen-rich fragments can be fully oxidized without CO as a poisoning intermediate. The resulting synergy of complementary effects of Au core and surface Ir leads to an outstanding performance of Au@PtIr for EOR as characterized by a low onset potential of 0.3 V and 8.3 A mg–1 all‑metals peak current with 57% currents generated via full ethanol oxidation.
A general feature of unconventional superconductors is the existence of a superconducting dome in the phase diagram. Here we report a series of discrete superconducting phases in the simplest ...iron-based superconductor, FeSe thin flakes, by continuously tuning the carrier concentration through the intercalation of Li and Na ions with a solid ionic gating technique. Such discrete superconducting phases are robust against the substitution of 20% S for Se, but they are vulnerable to the substitution of 2% Cu for Fe, highlighting the importance of the iron site being intact. The superconducting phase diagram for FeSe derivatives is given, which is distinct from that of other unconventional superconductors.
Flow stress and work hardening behaviour of Mg-Y binary alloys have been studied under uniaxial tension and compression at 4 K, 78 K and 298 K. Electron microscopy observations show that Yttrium ...forms multi-atomic clusters distributed randomly in Mg matrix. During thermomechanical processing, Y accumulates at the grain boundaries and controls recrystallization texture, which acquires lower intensity of the basal component and higher degree of randomness in comparison to polycrystalline Mg. Tensile and compressive yield stress of the alloys is temperature dependent and decreases as temperature increases from 4 K to 298 K. The grain size and solution strengthening contributions to the yield stress have been analyzed for all alloys and deformation temperatures. Critical resolved shear stress (CRSS) of individual deformation modes has been obtained from the modelling of the flow stress. These results show that Y strengthens most the <c+a> slip system, followed by pyramidal I, prismatic, twinning and basal systems. All slip systems exhibit monotonic increase of CRSS with Y concentration, but at different rates. Analysis of the solution strengthening component of the yield stress suggests that it is determined by activity of the basal slip participating in yielding. A correlation between the athermal hardening rate, Θh, and the amount of slip in individual deformation modes leads to the conclusion that higher athermal hardening rates are produced by a balanced contribution of basal and non-basal slip, whereas lower Θh is associated typically with less activity of <c+a> slip. Improved ductility of Mg-Y alloys is reflected in the type of dislocation microstructure developed during plastic flow and the character of the fracture surfaces. These alloys' characteristics are linked to the mechanical property data to obtain better understanding of the mechanisms responsible for the enhanced plasticity of Mg-Y alloys.
•Strain hardening and texture evolution of Mg-Y alloys have been studied under uniaxial tension and compression at 298 K, 78 K and 4 K.•The grain size and solution strengthening contributions to the yield stress have been analyzed.•Strengthening of individual deformation modes by Yttrium has been determined form rate-dependent crystal plasticity modeling of the flow stress.•A correlation between work hardening rate and the activity of different slip systems has been studied.•Mg-Y alloys exhibit quasi-brittle trans-granular fracture mode with evidence of Yttrium improving cohesive strength of grain boundaries, this has positive influence on ductility.
Postmenopausal osteoporosis (PMO) is a risk factor for periodontitis, and current therapeutics against PMO prevent the aggravated alveolar bone loss of periodontitis in estrogen-deficient women. Gut ...microbiota is recognized as a promising therapeutic target for PMO. Berberine extracted from Chinese medicinal plants has shown its effectiveness in the treatment of metabolic diseases such as obesity and diabetes via regulating gut microbiota. Here, we hypothesize that berberine ameliorates periodontal bone loss by improving the intestinal barriers by regulating gut microbiota under an estrogen-deficient condition. Experimental periodontitis was established in ovariectomized (OVX) rats, and the OVX-periodontitis rats were treated with berberine for 7 wk before sacrifice for analyses. Micro–computed tomography and histologic analyses showed that berberine treatment significantly reduced alveolar bone loss and improved bone metabolism of OVX-periodontitis rats as compared with the vehicle-treated OVX-periodontitis rats. In parallel, berberine-treated OVX-periodontitis rats harbored a higher abundance of butyrate-producing gut microbiota with elevated butyrate generation, as demonstrated by 16S rRNA sequencing and high-performance liquid chromatography analysis. Berberine-treated OVX-periodontitis rats consistently showed improved intestinal barrier integrity and decreased intestinal paracellular permeability with a lower level of serum endotoxin. In parallel, IL-17A-related immune responses were attenuated in berberine-treated OVX-periodontitis rats with a lower serum level of proinflammatory cytokines and reduced IL-17A+ cells in alveolar bone as compared with vehicle-treated OVX-periodontitis rats. Our data indicate that gut microbiota is a potential target for the treatment of estrogen deficiency–aggravated periodontal bone loss, and berberine represents a promising adjuvant therapeutic by modulating gut microbiota.
The current discrepancy between the Hubble constant,
H
0
, derived from the local distance ladder and from the cosmic microwave background is one of the most crucial issues in cosmology, as it may ...possibly indicate unknown systematics or new physics. Here, we present a novel non-parametric method to estimate the Hubble constant as a function of redshift. We establish independent estimates of the evolution of Hubble constant by diagonalizing the covariance matrix. From type Ia supernovae, baryon acoustic oscillation data and the observed Hubble parameter data, a decreasing trend in the Hubble constant with a significance of a 5.6
σ
confidence level is found. At low redshift, its value is dramatically consistent with that measured from the local distance ladder and it drops to the value measured from the cosmic microwave background at high redshift. Our results may relieve the Hubble tension, with a preference for recent solutions, especially with respect to novel physics.
Ganymede is the only Solar System moon known to generate a permanent magnetic field. Jovian plasma motions around Ganymede create an upstream magnetopause, where energy flows are thought to be driven ...by magnetic reconnection. Simulations indicate Ganymedean reconnection events may be transient, but the nature of magnetopause reconnection at Ganymede remains poorly understood, requiring an assessment of reconnection onset theory. We present an analytical model of steady‐state conditions at Ganymede's magnetopause, from which the first Ganymedean reconnection onset assessment is conducted. We find that reconnection may occur wherever Ganymede's closed magnetic field encounters Jupiter's ambient magnetic field, regardless of variations in magnetopause conditions. Unrestricted reconnection onset highlights possibilities for multiple X lines or widespread transient reconnection at Ganymede. The reconnection rate is controlled by the ambient Jovian field orientation and hence driven by Jupiter's rotation. Future progress on this topic is highly relevant for the JUpiter ICy moon Explorer mission.
Plain Language Summary
Ganymede is the largest moon of Jupiter and the only Solar System moon that produces its own magnetic field. Ganymede's magnetic field is surrounded by Jupiter's much larger magnetic field, which flows around the moon like a river flowing around a rock. The boundary where Jupiter's magnetic field first encounters Ganymede's is called the magnetopause. At this boundary, energy and mass can move between the two magnetic fields through a process called magnetic reconnection. Our paper introduces a simple model of Ganymede's magnetopause and uses this model to show where reconnection can occur on the boundary. We find that reconnection can occur anywhere on the magnetopause for any plausible environmental conditions around Ganymede, so the locations where these energy‐releasing events occur may be particularly unpredictable. The rate of energy released by reconnection meanwhile depends on near‐Ganymede conditions, which change significantly as Jupiter rotates. These results will help inform the planning of the JUpiter ICy moon Explorer mission to Ganymede.
Key Points
We create the first analytical model of conditions at Ganymede‐Jupiter magnetopause and assess magnetic reconnection onset theory
Reconnection may occur anywhere on the magnetopause where Ganymede's closed magnetic field meets the ambient field of Jupiter
The average reconnection rate at Ganymede exhibits a Jovian‐diurnal variation and hence is driven by Jupiter's rotation
Hydrogen oxidation and evolution on Pt in acid are facile processes, while in alkaline electrolytes, they are 2 orders of magnitude slower. Thus, developing catalysts that are more active than Pt for ...these two reactions is important for advancing the performance of anion exchange membrane fuel cells and water electrolyzers. Herein, we detail a 4-fold enhancement of Pt mass activity that we achieved using single-crystalline Ru@Pt core–shell nanoparticles with two-monolayer-thick Pt shells, which doubles the activity on Pt–Ru alloy nanocatalysts. For Pt specific activity, the two- and one-monolayer-thick Pt shells exhibited enhancement factors of 3.1 and 2.3, respectively, compared to the Pt nanocatalysts in base, differing considerably from the values of 1 and 0.4, respectively, in acid. To explain such behavior and the orders of magnitude difference in activity on going from acid to base, we performed kinetic analyses of polarization curves over a wide range of potential from −250 to 250 mV using the dual-pathway kinetic equation. From acid to base, the activation free energies increase the most for the Volmer reaction, resulting in a switch of the rate-determining step from the Tafel to the Volmer reaction, and a shift to a weaker optimal hydrogen binding energy. The much higher activation barrier for the Volmer reaction in base than in acid is ascribed to one or both of the two catalyst-insensitive factors: slower transport of OH– than H+ in water and a stronger O–H bond in water molecules (HO–H) than in hydrated protons (H2O–H+).
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