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ZnTe epitaxial layers with different crystalline quality were grown by molecular beam epitaxy. ZnTe:O was achieved by oxygen incorporation in ZnTe films using ion implantation. The proper concentrations of O ions attributed to the formation of the intermediate band which was approximately 1.88 eV above the valence band maximum. Pulsed laser melting was then carried out on the samples. ZnTe with high crystalline quality and appropriate concentrations of oxygen ions led to the improvements of absorption efficiency of the intermediate band. The results suggest that factors such as the crystalline quality and the dose of O concentration are important to achieve better ZnTe:O intermediate-band photovoltaic materials. The way we utilize to fabricate ZnTe:O intermediate band solar cell materials is applicable, and the position and intensity of O states could be well controlled. [ABSTRACT FROM AUTHOR]

Background and Purpose: Understanding the stroke mechanism of middle cerebral artery (MCA) atherosclerosis is important for stroke triage and future trial design. The aim of this study was to characterize intrinsic MCA plaque and acute cerebral infarct in vivo by using high-resolution black-blood (BB) and diffusion-weighted magnetic resonance (MR) imaging and to investigate the relationship between plaque features and infarct patterns.Methods: A single-center retrospective study was conducted at a tertiary referral center between March 2017 and August 2019. Patients consecutively admitted for acute ischemic stroke with MCA stenosis underwent diffusion-weighted and BB MR imaging. Plaque features and infarct patterns were assessed. The association between plaque features and infarct patterns (binary variable: single/multiple) was evaluated using a multivariate logistic regression model.Results: Of 49 patients with MCA atherosclerotic stenosis, diffusion-weighted MR imaging showed that 28 patients (57%) had multiple acute cerebral infarcts and 21 patients had single acute cerebral infarcts. In contrast to single infarct, multiple infarcts were associated with greater plaque burden (81.9±7.24 versus 71.3±13.7; P=0.012). A multivariate logistic regression model adjusted for 7 potential confounders confirmed a statistically significant positive association between plaque burden and multiple acute infarcts (adjusted R2 =0.432, P< 0.001). The rate of plaque surface irregularity was significantly greater in patients with multiple infarcts than those with single infarct (71% versus 43%, P=0.044). For single acute penetrating artery infarct, patients with infarct size > 2cm had greater plaque burden compared with patients with infarct size < 2cm (75.3±13.4 versus 63.4±10.9; P = 0.016).Conclusions: Increased plaque burden, plaque surface irregularity in patients with MCA stenosis is associated with its likelihood to have caused an artery-to-artery embolism that produces multiple cerebral infarcts, especially along the border zone region, and increased plaque burden may promote subcortical single infarct size by occluding penetrating arteries. Our results provide important insight into stroke mechanism of MCA atherosclerosis. [ABSTRACT FROM AUTHOR]

Zinc telluride layers were directly grown on highly-lattice-mismatched Si (111) substrates by molecular beam epitaxy (MBE). Reflection high-energy electron diffraction (RHEED), X-ray diffraction (XRD) and atomic force microscopy (AFM) were used to study the growth mechanism and crystal quality of ZnTe on Si (111). The results show that the growth mode related with the Ⅵ/Ⅱ beam pressure ratio is one of important factors affecting the initial growing process, crystal quality and morphology of ZnTe epitaxial thin films. From in situ RHEED observations, two-dimensional (2D) growth mode was found upon increasing Ⅵ/Ⅱ beam pressure ratio to 3.3 while three-dimensional (3D) growth mode remained in Zn-rich atmosphere or at Ⅵ/Ⅱ beam pressure ratio larger than 6. Small full-width at half-maximum (~540 arcsec) showed that the growth of ZnTe on Si (111) in Te-rich atmosphere, especially in a layer-by-layer mode, was more suitable for nucleation growth. • Zinc telluride layers were directly grown on highly-lattice-mismatched Si (111) by MBE. • The growth mode is responsible for the initial growing process and crystal quality of ZnTe epilayers. • In a 2D growth mode, we obtained ZnTe (111) epilayers with the FWHM as low as ~540 arcsec. [ABSTRACT FROM AUTHOR]