Co-alloying solid solution was regarded as a convenient approach to optimize the thermoelectric properties. In this study, the densified Cu2–x (MnFeNi) x Se1–y Te y (x = 0–0.09; y = 0–0.03) designed by entropy engineering was prepared via microwave melting and hot-pressing sintering. The scattering mechanism and thermoelectric performance of Cu2Se were evaluated. Due to the regulation of the carrier concentration and structural stabilization of the β-phase, the electrical performance was significantly enhanced. Moreover, the infrared spectroscopy analysis and the decrease in sound velocity unambiguously demonstrated the existence of a lattice softening effect of bulk Cu2Se. By manipulating the lattice conductivity using entropy engineering, the thermal transport property gradually decreased (∼0.4 W m–1 K–1 at 300 K) due to the lattice softening effect and phonon scattering mechanism. The obtained zT max was 1.37 at 750 K in the Cu2.91(MnFeNi)0.09Se0.99Te0.01 sample.

Forming co-alloying solid solutions has long been considered as an effective strategy for improving thermoelectric performance. Herein, the dense Cu2−x(MnFeNi)xSe (x = 0–0.09) with intrinsically low thermal conductivity was prepared by a melting-ball milling-hot pressing process. The influences of nanostructure and compositional gradient on the microstructure and thermoelectric properties of Cu2Se were evaluated. It was found that the thermal conductivity decreased from 1.54 Wm−1K−1 to 0.64 Wm−1K−1 at 300 K via the phonon scattering mechanisms caused by atomic disorder and nano defects. The maximum zT value for the Cu1.91(MnFeNi)0.09Se sample was 1.08 at 750 K, which was about 27% higher than that of a pristine sample.

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Background: Intravenous thrombolysis (IVT) and bridging therapy (BT) (IVT+mechanical thrombectomy [MT]) are the main treatments for acute ischemic stroke (AIS). Recent studies suggested that the curative effects of MT alone and BT are equivalent. However, there is no consensus regarding the curative effect and safety of MT alone. Therefore, a systematic review and meta-analysis are needed for further clarification.   Methods: Seven databases, including PubMed, EMBASE, and Web of Science, were searched up to May 2021 for studies on MT alone and BT for the treatment of AIS. The modified Rankin scale (mRS) score and recanalization rate were the efficacy outcomes. Symptomatic and asymptomatic intracranial hemorrhage (SICH and aSICH) and mortality were the safety outcomes. RevMan 5.4 was used for analysis.   Results: Thirty-five studies including 10,462 patients (MT alone: 4,612, BT: 5850) were selected. The improvement in the mRS score (mRS1: risk ratio [RR]=1.22, 95% confidence interval [CI] 1.09-1.35; P<.05; mRS2: RR=1.21, 95% CI 1.12-1.31; P<.05) was greater and the recanalization rate (RR=1.06, 95% CI 1.02-1.09; P<.05) was higher with BT than with MT alone. The rates of overall intracranial hemorrhage (RR=1.20, 95% CI 1.07-1.34; P <.05) and aSICH (RR=1.31, 95% CI 1.41-1.51; P<.05) were lower after MT alone than after BT. There was no significant difference in the rate of SICH (RR=1.05, 95% CI.87-1.26; P>.05). The mortality rate (RR=.76, 95% CI.70-.83; P<.05) was higher after MT alone than after BT.   Conclusions: MT alone is inferior to BT regarding improvements in neurological function and recanalization and is associated with a higher mortality rate, although the associated rate of aSICH is lower.