A micromechanical study on the effects of precipitation on the mechanical properties of CoCrFeMnNi high entropy alloys with various annealing temperatures.

The CoCrFeMnNi high entropy alloys remain an active field over a decade owing to its excellent mechanical properties. However, the application of CoCrFeMnNi is limited because of the relatively low tensile strength. Here we proposed a micromechanical model which adopted from the theory of dislocation density to investigate the strengthening mechanisms of precipitation of chromium-rich non-equiatomic CoCrFeMnNi alloy. The microstructures of CoCrFeMnNi were obtained directly from SEM-BSE images with different annealing temperatures. The proposed framework is validated by comparing simulations with experiments of uniaxial tensile tests on the CoCrFeMnNi alloys under different annealing temperatures. The stress-strain curves indicate that the precipitate has greater influence on post-yield hardening than the initial yielding strength. In addition, we identified that the particle distribution, controlled by the average size of the particle and the volume fraction of precipitation, can significantly enhance the strengthening effect. The numerical results indicate that HEAs with a precipitate distribution closer to a normal distribution and with smaller average size will tend to have higher strength and ductility.

Neutrophil-to-lymphocyte ratio in predicting neurologic outcome of patients with acute ischemic stroke treated with intravenous thrombolytics.

BACKGROUND: Recombinant tissue plasminogen activator (rtPA) is currently the most standard treatment for patients with acute ischemic stroke (AIS). However, rtPA treatment may further enhance the immune response poststroke. This study is to investigate the clinical utility of white blood-based inflammatory biomarkers in predicting neurologic outcomes among AIS patients receiving rtPA. METHODS: A retrospective observational cohort study of 100 patients with AIS treated with intravenous rtPA was conducted in an urban tertiary hospital in Taiwan. Favorable neurological outcome defined as modified Rankin Scale (mRS) score 0 to 2 in poststroke follow-up was the primary outcome measure. Baseline and post-rtPA neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) were investigated for potential predictors. RESULTS: These patients had a mean age of 71.3 ± 13.7 years and the average of initial National Institute of Health Stroke Scale was 12.7 ± 6.5. Using multiple regression analysis, PLR was not an independent factor; however, both baseline and post-rtPA NLR were independent factors predicting favorable neurological outcome at 3, 6, 12 months after a stroke. The area under the receiver operating characteristic curve for baseline and post-rtPA NLR were 0.645 (95% confidence interval [CI], 0.537-0.753) and 0.769 (95% CI, 0.676-0.862) (Z score = 2.086) in 3-month, 0.645 (95% CI, 0.537-0.752) and 0.791 (95% CI, 0.701-0.880) (Z score = 2.471) in 6-month, and 0.646 (95% CI, 0.538-0.754) and 0.813 (95% CI, 0.728-0.898) (Z score = 2.857) in 12-month poststroke follow-up. CONCLUSION: For AIS patients treated with rtPA, both lower baseline and post-rtPA NLR levels were independently associated with a favorable neurologic outcome in serial mid- and long-term follow-up. Post-rtPA NLR was superior to baseline NLR in discriminative performance for neurologic prognosis.