High-pressure structural and electronic properties of InN

We theoretically study the electronic properties, and,pressure-induced solid-solid phase transformation by InN by using the first-principles pseudopotential method. The wurtzite (B4), rocksalt (B1), zinc-blende (B3), CsCl-type (B2), and Cmcm crystal structures of InN have been considered. The calculations indicate that the phase transitions from B4 phase to B1 phase and B3 structure to B1 structure occur at a transition pressure of 10.2 and 9.6 GPa, respectively. The detailed volume changes during the phase transformations were analyzed. Moreover, the analysis of the band structure indicates that the bandgap of B4 phase is direct, while B1 phase is indirect under high-pressure. The mechanism of these changes of band structures was analyzed. The positive pressure derivative of the indirect and direct gap indicates that it is impossible to make B1 phase of InN metallic up to 200 GPa. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

Structural stability and optical properties of AlN explored by ab initio calculations

Pressure-induced structural phase transformations, electronic and optical properties of AlN are investigated by first-principles method based on the plane-wave basis set. The wurtzite (B4), zincblende (B3), rocksalt (B1), b-beta- Sn, NiAs, anti-NiAs, cinnabar, and simple cubic with 16-atom basis (SC16) phases of AlN have been considered. The calculations demonstrate that there exists a phase transition from B4 structure to B1 phase at the transition pressure of 12.7 GPa. Analysis of band structures suggests that the B4-AlN has a direct gap of 4.13 eV, while B1 phase become indirect under high pressure. The mechanism of these changes of band structures is analyzed. The positive pressure derivative of band gap energies for B1 phase might be due to the absence of d occupations in the valence bands. In addition, the imaginary parts of dielectric function for the polarization in the xy plane and average of the imaginary parts of dielectric function over three Cartesian directions were calculated. The origin of the spectral peaks was interpreted based on the electronic structure. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved

A super-resolution method-based pipeline for fundus fluorescein angiography imaging

Abstract Background Fundus fluorescein angiography (FFA) imaging is a standard diagnostic tool for many retinal diseases such as age-related macular degeneration and diabetic retinopathy. High-resolution FFA images facilitate the detection of small lesions such as microaneurysms, and other landmark changes, in the early stages; this can help an ophthalmologist improve a patient’s cure rate. However, only low-resolution images are available in most clinical cases. Super-resolution (SR), which is a method to improve the resolution of an image, has been successfully employed for natural and remote sensing images. To the best of our knowledge, no one has applied SR techniques to FFA imaging so far. Methods In this work, we propose a SR method-based pipeline for FFA imaging. The aim of this pipeline is to enhance the image quality of FFA by using SR techniques. Several SR frameworks including neighborhood embedding, sparsity-based, locally-linear regression and deep learning-based approaches are investigated. Based on a clinical FFA dataset collected from Second Affiliated Hospital to Xuzhou Medical University, each SR method is implemented and evaluated for the pipeline to improve the resolution of FFA images. Results and conclusion As shown in our results, most SR algorithms have a positive impact on the enhancement of FFA images. Super-resolution forests (SRF), a random forest-based SR method has displayed remarkable high effectiveness and outperformed other methods. Hence, SRF should be one potential way to benefit ophthalmologists by obtaining high-resolution FFA images in a clinical setting

Temperature-Dependent Enantio- and Diastereodivergent Synthesis of Amino Acids with One or Multiple Chiral Centers

A general and facile methodology for temperature-dependent enantiodivergent and diastereodivergent synthesis of amino acids with one or multiple chiral centers was developed. Camphor-based tricyclic iminolactones attack electrophiles from the <i>endo</i> face at low temperature (−78 to −40 °C) and from the <i>exo</i> face at high temperature (−10 to 25 °C)

Formal Synthesis of Cephalotaxine

A formal synthesis of cephalotaxine, the parent member of the <i>Cephalotaxus</i> alkaloids, was achieved. It features a practical four-step assembly of the benzazepine-bearing pentacyclic ring system through two alkylation reactions, acidic hydrolysis, and aldolization

Mobile phone use and glioma risk: A systematic review and meta-analysis

<div><p>Objective</p><p>Many studies have previously investigated the potential association between mobile phone use and the risk of glioma. However, results from these individual studies are inconclusive and controversial. The objective of our study was to investigate the potential association between mobile phone use and subsequent glioma risk using meta-analysis.</p><p>Methods</p><p>We performed a systematic search of the Science Citation Index Embase and PubMed databases for studies reporting relevant data on mobile phone use and glioma in 1980–2016. The data were extracted and measured in terms of the odds ratio (OR) and 95% confidence interval (CI) using the random effects model. Subgroup analyses were also carried out. This meta-analysis eventually included 11 studies comprising a total 6028 cases and 11488 controls.</p><p>Results</p><p>There was a significant positive association between long-term mobile phone use (minimum, 10 years) and glioma (OR = 1.44, 95% CI = 1.08–1.91). And there was a significant positive association between long-term ipsilateral mobile phone use and the risk of glioma (OR = 1.46, 95% CI = 1.12–1.92). Long-term mobile phone use was associated with 2.22 times greater odds of low-grade glioma occurrence (OR = 2.22, 95% CI = 1.69–2.92). Mobile phone use of any duration was not associated with the odds of high-grade glioma (OR = 0.81, 95% CI = 0.72–0.92). Contralateral mobile phone use was not associated with glioma regardless of the duration of use. Similarly, this association was not observed when the analysis was limited to high-grade glioma.</p><p>Conclusions</p><p>Our results suggest that long-term mobile phone use may be associated with an increased risk of glioma. There was also an association between mobile phone use and low-grade glioma in the regular use or long-term use subgroups. However, current evidence is of poor quality and limited quantity. It is therefore necessary to conduct large sample, high quality research or better characterization of any potential association between long-term ipsilateral mobile phone use and glioma risk.</p></div