RESUMEN
Density-dependent speed is studied in a two-dimensional active colloid in which the colloidal particles are propelled by an external electric field via a Quincke rotation. Above the critcal electric field, dense dynamic clusters form spotaneously, in which the particles are highly aligned in velocity and move much faster than isolated units. Detailed observations on pair collision reveal that the alignment of velocity is induced by the long-ranged hydrodynamic interactions and the improvement of speed in the clusters arises from pair aligning in which two particles are closely paired and rotate synchronically. In the aligning state, the short-range in-plane dipole-dipole attraction enhances the rotation torque and gives rises to a larger rolling speed. The pair aligning becomes difficult and unstable at high electric field where the normal dipole-dipole repulsion becomes dominant. As a consequence, the dependence of speed on density becomes weak increasingly upon the increase of the electric field. This result offers an interpretation for the discrepancy between our and previous observations on Quincke rollers.
RESUMEN
The effects of grain boundary misorientation angle (θ) on mechanical properties and the mechanism of plastic deformation of the Ni/Ni3Al interface under tensile loading were investigated using molecular dynamics simulations. The results show that the space lattice arrangement at the interface is dependent on grain boundary misorientations, while the interfacial energy is dependent on the arrangement. The interfacial energy varies in a W pattern as the grain boundary misorientation increases from 0° to 90°. Specifically, the interfacial energy first decreases and then increases in both segments of 0-60° and 60-90°. The yield strength, elastic modulus, and mean flow stress decrease as the interfacial energy increases. The mechanism of plastic deformation varies as the grain boundary misorientation angle (θ) increases from 0° to 90°. When θ = 0°, the microscopic plastic deformation mechanisms of the Ni and Ni3Al layers are both dominated by stacking faults induced by Shockley dislocations. When θ = 30°, 60°, and 80°, the mechanisms of plastic deformation of the Ni and Ni3Al layers are the decomposition of stacking faults into twin grain boundaries caused by extended dislocations and the proliferation of stacking faults, respectively. When θ = 90°, the mechanisms of plastic deformation of both the Ni and Ni3Al layers are dominated by twinning area growth resulting from extended dislocations.
RESUMEN
BACKGROUND: The activation of the arginine vasopressin system may be involved in the pathology of stroke and diabetes. In this study, we therefore evaluated the short-term prognostic value of early measurement of plasma copeptin levels in Chinese patients with type 2 diabetes mellitus (T2DM) and acute ischemic stroke (AIS). METHODS: From July 2014 to June 2015, all T2DM patients with first-ever AIS were included. Plasma levels of copeptin were tested at admission. The prognostic value of copeptin to predict the functional outcome and mortality 3months after stroke was compared with the National Institutes of Health Stroke Scale score and with other known outcome predictors. RESULTS: We recorded 247 stroke patients with T2DM. The copeptin levels were obtained in those patients with a median value of 14.3pmol/L (IQR, 9.5-17.1pmol/L). At 3-month follow-up, a favorable functional outcome was found in 86 patients (34.8%). Plasma copeptin levels in patients with an unfavorable outcome were significantly greater than those in patients with a favorable outcome (16.2 [IQR, 12.2-20.3] vs. 12.4 [IQR, 8.6-15.2] pmol/L; Z=5.399; P<0.0001). In univariate logistic regression analysis, with an unadjusted OR of 1.123 (95% CI, 1.072-1.177, P<0.001), copeptin had a strong association with unfavorable functional outcome. In multivariate analyses, a copeptin level in the highest inter-quartile (>17.1pmol/L) was associated with a higher risk of unfavorable functional outcome (OR=4.62; 95% CI=2.63-9.21; P<0.001). After adjusting for other outcome predictors, a copeptin level in the highest inter-quartile (>17.1pmol/L) was associated with a higher risk of mortality (OR=5.12; 95% CI=2.20-11.38; P<0.001). CONCLUSION: Our study suggested that copeptin levels may reliably predict short-term stroke prognosis at its onset in Chinese patients with T2DM and stroke.