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[Prevalence and associated factors for poor nutrition among young children under Some yrs . old in Hunan province].
Metal halide perovskites have attracted increasing attention due to their superior optical and electrical characteristics, flexible tunability, and easy fabrication processes. Apart from their unprecedented successes in photovoltaic devices, lasing action is the latest exploitation of the optoelectronic performance of perovskites. Among the substantial body of research on the configuration design and light emission quality of perovskite lasers, the random laser is a very interesting stimulated emission phenomenon with unique optical characteristics. In this review article, we first comprehensively overview the development of perovskite-based optoelectronic devices and then focus our discussion on random lasing performance. After an introduction to the historical development of versatile random lasers and perovskite random lasers, we summarize several synthesis methods and discuss their material configurations and stability in synthesized perovskite materials. Following this, a theoretical approach is provided to explain the random lasing mechanism in metal halide perovskites. Finally, we propose future applications of perovskite random lasers, presenting conclusions as well as future challenges, such as quality stability and toxicity reduction, of perovskite materials with regard to practical applications in this promising field.Two-dimensional (2D) semiconductor is a promising material for future electronics. It is believed that the flexural phonon (FP) induced scattering plays an important role in the room-temperature carrier mobility, and the substrate can significantly affect such scattering. Here we develop an 'implicit' substrate model, which allows us to effectively quantify different effects of the substrate on the FP scattering. In conjunction with the first-principles calculations, we study the intrinsic mobilities of the holes in Sb and electrons in MoS2as representative examples for 2D semiconductors. We find that the FP scattering is not dominant and is weaker than other scatterings such as that induced by longitudinal acoustic (LA) phonon. This is due to the significantly smaller electron-phonon-coupling (EPC) matrix elements for the FP compared with that for the LA phonon in the free-standing case; although the substrate enhances the FP EPC, it suppresses the FP population, making the FP scattering still weaker than the LA scattering. Our work improves the fundamental understanding of the role of FP and its interaction with the substrate in carrier mobility, and provides a computational model to study the substrate effects.Viscosity variation of solvent in local regions near a solid surface, be it a biological surface of a protein or an engineered surface of a nanoconfinement, is a direct consequence of intermolecular interactions between the solid body and the solvent. The current coarse-grained molecular dynamics study takes advantage of this phenomenon to investigate the anomaly in a solvated protein's rotational dynamics confined using a representative solid matrix. The concept of persistence time, the characteristic time of structural reordering in liquids, is used to compute the solvent's local viscosity. With an increase in the degree of confinement, the confining matrix significantly influences the solvent molecule's local viscosity present in the protein hydration layer through intermolecular interactions. This effect contributes to the enhanced drag force on protein motion, causing a reduction in the rotational diffusion coefficient. Simulation results suggest that the direct matrix-protein non-bonded interaction is responsible for the occasional jump and discontinuity in orientational motion when the protein is in very tight confinement.Dose reduction in cerebral CT perfusion (CTP) imaging is desirable but is accompanied by an increase in noise that can compromise the image quality and the accuracy of image-based haemodynamic modelling used for clinical decision support in acute ischaemic stroke. GCN2-IN-1 The few reported methods aimed at denoising low-dose CTP images lack practicality by considering only small sections of the brain or being computationally expensive. Moreover, the prediction of infarct and penumbra size and location-the chief means of decision support for treatment options-from denoised data has not been explored using these approaches. In this work, we present the first application of a 3D generative adversarial network (3D GAN) for predicting normal-dose CTP data from low-dose CTP data. Feasibility of the approach was tested using real data from 30 acute ischaemic stroke patients in conjunction with low dose simulation. The 3D GAN model was applied to 643voxel patches extracted from two different configurations of the CTP data-frame-based and stacked. The method led to whole-brain denoised data being generated for haemodynamic modelling within 90 s. Accuracy of the method was evaluated using standard image quality metrics and the extent to which the clinical content and lesion characteristics of the denoised CTP data were preserved. Results showed an average improvement of 5.15-5.32 dB PSNR and 0.025-0.033 structural similarity index (SSIM) for CTP images and 2.66-3.95 dB PSNR and 0.036-0.067 SSIM for functional maps at 50% and 25% of normal dose using GAN model in conjunction with a stacked data regime for image synthesis. Consequently, the average lesion volumetric error reduced significantly (p-value less then 0.05) by 18%-29% and dice coefficient improved significantly by 15%-22%. We conclude that GAN-based denoising is a promising practical approach for reducing radiation dose in CTP studies and improving lesion characterisation.Polymeric carbon nitride (C3N4) is currently the most potential nonmetallic photocatalyst, but it suffers from low catalytic activity due to rapid electron-hole recombination behavior and low specific surface area. The morphology control of C3N4is one of the effective methods used to achieve higher photocatalytic performance. Here, bulk, lamellar and coralloid C3N4were synthesized using different chemical methods. The as-prepared coralloid C3N4has a higher specific surface area (123.7 m2 · g-1) than bulk (5.4 m2 · g-1) and lamellar C3N4(2.8 m2 · g-1), thus exhibiting a 3.15- and 2.59-fold higher photocatalytic efficiency for the selective oxidation of benzyl alcohol than bulk and lamellar C3N4, respectively. Optical characterizations of the photocatalysts suggest that coralloid C3N4can effectively capture electrons and accelerate carrier separation, which is caused by the presence of more nitrogen vacancies. Furthermore, it is demonstrated that superoxide radicals (·O2-) and holes (h+) play major roles in the photocatalytic selective oxidation of benzyl alcohol using C3N4as a photocatalyst.
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