Negative thermal quenching CsPbBr3 glass-ceramic based on intrinsic radiation and vacancy defect co-induced dual-emission

Halide perovskite glass-ceramic has recently moved into the center of the attention of perovskite research due to their potential for temperature sensing. However, quantum dots glass-ceramic with excellent luminescence performance still needs to be combined with rare-earth (RE) ions to accurately measure temperature. In this work, a novel non-RE doped dual-emission (460 nm and 512 nm) CsPbBr₃ quantum dots was obtained in telluride glass via the friction crystallization method, where 512 nm was derived from intrinsic luminescence of quantum dots, and 460 nm was originated from thermally induced bromine vacancy, which can be used for temperature sensing. Fluorescence intensity ratio results indicate that the relative sensitivity of dual-emission could reach 5.6 % K^?1 at 323 K. The discovery of non-RE doped CsPbBr₃ QDs glass-ceramic with negative thermal quenching uncovers a new optional sensing glass material that surpass traditional RE-doped QDs glass by their tunability and sensitivity.     

Doping manganese into CsPb(Cl/Br)3 quantum dots glasses: Dual-color emission and super thermal stability

CsPbX₃ (X = Cl, Br, I) perovskite quantum dots (QDs) represent bright and tunable photoluminescence, it is regrettable that the air instability and poor water resistant properties prevent their application in optoelectronic devices. At the same time, the toxicity of lead is also a major factor restricting its development. As a consequence, we demonstrate the partial replacement of Pb with Mn through conventional melt-quenching and heat-treatment method preparation of Mn-doped CsPb(Cl/Br)₃ QD glass. Mn-doped CsPb(Cl/Br)₃ QD glass exhibits high luminescent intensity like QDs. It is important that Mn-doped CsPb(Cl/Br)₃ QD glass with Dual-Color maintained the same lattice structure like Mn-doped CsPb(Cl/Br)₃ QDs, and highly homogeneous spectral characteristics of Mn luminescence. The intensity and position of this Mn-related emission are also tunable by altering the experimental parameters, such as the Pb-to-Mn feed ratio, annealing temperature. More importantly, the as-prepared orange Mn-doped CsPb(Cl/Br)₃ QD glass was employed to fabricate white LEDs combined with a commercial Ce³⁺:Y₃Al₅O₁₂ phosphor-in-glass (Ce-PiG) on top of a InGaN blue chip. And the constructed WLEDs generate a warm white with an optimal luminous efficacy (LE) of 67.00 lm/W, a high CRI of 81.4, and a low CCT of 4902 K.     

Combination of nuclear magnetic resonance spectroscopy and nonlinear methods to analyze the copolymerization of phosphonic acid derivatives

We demonstrate in this study that the combination of modern inline monitoring methods [here: inline nuclear magnetic resonance (NMR)] with simulations gains more exact and profound kinetic results than previously used methods like linearization without that combination. The ¹H-NMR spectroscopic data (more than 100 data points) are used to construct the copolymerization diagram. The reactivity ratios are obtained applying the van Herks nonlinear least square method. The examination of the radical copolymerization of 2-hydroxyethyl methacrylate (HEMA) with (2-{[2-(ethoxycarbonyl)prop-2-en-1-yl]oxy}ethyl) phosphonic acid (ECPPA) as important adhesive monomer used in dentistry yields reactivity ratios of r_HEMA = 1.83; r_ECPPA = 0.42. The copolymerization diagram reflects nonideal, non-azeotropic copolymerization. The sequence distribution of the obtained by Monte Carlo simulation indicates the generation of statistical copolymers. As an important finding, it is demonstrated that the repeating units responsible for etching and adhesion are arranged over the whole polymer chain, which is necessary to achieve proper functionality. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48256.     

The Investigation of the Fractional-View Dynamics of Helmholtz Equations Within Caputo Operator

It is eminent that partial differential equations are extensively meaningful in physics, mathematics and engineering. Natural phenomena are formulated with partial differential equations and are solved analytically or numerically to interrogate the system’s dynamical behavior. In the present research, mathematical modeling is extended and the modeling solutions Helmholtz equations are discussed in the fractional view of derivatives. First, the Helmholtz equations are presented in Caputo’s fractional derivative. Then Natural transformation, along with the decomposition method, is used to attain the series form solutions of the suggested problems. For justification of the proposed technique, it is applied to several numerical examples. The graphical representation of the solutions shows that the suggested technique is an accurate and effective technique with a high convergence rate than other methods. The less calculation and higher rate of convergence have confirmed the present technique’s reliability and applicability to solve partial differential equations and their systems in a fractional framework.     

Facet engineered TiO2 hollow sphere for the visible-light-mediated degradation of antibiotics via ligand-to-metal charge transfer

Efficient removal of tetracycline (TC) under visible-light irradiation over TiO₂-based photocatalysts remains a challenge based on the fact that the reported photocatalytic systems still suffer from weak visible-light absorption and/or inefficient charge separation. Herein, we constructed {101} and {001} facets co-exposed TiO₂ hollow sphere (001-HT) via a gentle NaF treatment, in which the hollow mesoporous feature can trap incident light for a long time to improve photons efficiently. Meanwhile, the as-formed facet heterojunction significantly facilitates the charge separation. As a result, the 001-HT exhibits a high removal rate (~90.1%) of TC under visible-light irradiation, beyond the values of many reported TiO₂-based photocatalysts. Most importantly, we further expound the ligand-to-metal charge transfer mechanism towards TiO₂-assisted degradation of TC under visible-light irradiation, which effectively clarifies the confusion about the origin of pure TiO₂ visible-light activity towards TC degradation because both TiO₂ and TC do not exhibit any visible-light catalytic activity. Therefore, this work provides a new insight in revealing the mechanism of visible-light-mediated TC degradation over pure TiO₂ photocatalyst.     

Synthesis of “walnut-like” BiOCl/Br solid solution photocatalyst by electrostatic self-assembly method

In this paper, under the control strategy of surface charge of BiOCl photocatalyst and the electrostatic adsorption of anions and cations in potassium bromide (KBr) and polyvinylpyrrolidone (PVP), the self-assembly of “walnut-like” BiOCl/Br solid solution nanophotocatalyst at a lower temperature water bath was proposed for the first time. X-ray diffraction (XRD), Raman, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), energy-dispersive system (EDS), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET), UV-Vis, photoluminescence spectroscopy (PL) and Mott-Schottky curve, transient photocurrent densities, and electrochemical impedance spectroscopy (EIS) were used to analyze the properties of materials, including its morphology, element distribution and chemical states, specific surface area, electrochemical property, and photogenic charge transfer. Based on the degradation performance of RhB dye wastewater and phenol in visible and ultraviolet light, and the band structure of BiOCl/Br solid solution, the reason for the improved photocatalytic activity was deeply discussed, and the possible degradation mechanism was also put forward. The above results show that Br⁻ can be inserted into the crystal lattice of BiOCl under the effect of electrostatic adsorption to form solid solution by the interaction between atomic orbitals, which not only reduces the bandgap width but also improves the separation and mobility of photogenic electrons and holes, causing the absorbed light to shift red to the visible region. In addition, when the n_Br⁻/n_Cl⁻ = 0.67, “walnut-like” BiOCl/Br solid solution was formed, and this kind of special core-shell structure not only can increase the specific surface area, increase the number of active sites, but also can make the light reflect and refract many times in the cavity and further increase the utilization rate of light energy, and then the best photocatalytic activity was achieved. This study provides an new method to enhance the photocatalytic performance of BiOCl and be conducive to the development of modern material science.     

β-环糊精协同乙烯基咪唑离子液体脱除溶剂油中的萘

采用1-乙烯基-3-正丁基溴代咪唑离子液体（[VBIM]Br）为脱除剂，在β-环糊精协同作用下萃取溶剂油中的萘。本实验考察了不同单因素条件在[VBIM]Br离子液体与β-环糊精共同作用下对溶剂油中脱萘率的影响，同时通过响应面法优化脱除工艺条件。实验结果表明：[VBIM]Br离子液体与β-环糊精共同作用下对萘的萃取率比单独利用[VBIM]Br离子液体提高了15%以上，萃取率达到90%以上。离子液体简单回收后，重复使用5次过后，脱除率仍在80%以上。实验通过红外分析和紫外光谱分析了[VBIM]Br离子液体协同β-环糊精脱萘的机理，与[VBIM]Br离子液体协同作用下，β-环糊精对萘存在包合作用，实现了对溶剂油中萘的脱除。     

污水槽液位计的改造

阐述了射频导纳物位开关在有搅拌的液体槽上使用的缺陷，同时根据实践经验，提出可行的改造方案，用超声波液位计代替射频导纳物位开关，从软件上实现联锁控制。     

七氟丙烷气体清洁灭火剂的灭火原理

基于哈龙（Halon）灭火剂的消防产品是一种最为有效的气体消防系统。根据《蒙特利尔议定书》的建议，一些新的清洁消防灭火剂将用来取代哈龙减火剂。其中一种候选者就是七氟丙烷（Heptafluoropropane）灭火剂以及基于七氟丙烷的全覆盖灭火系统正开始应用于电脑机房、电信交换投施等领域。然而，大泉仍未封七氟丙烷灭火剂的灭火原理有一个全面了解。该类型系统的操作是有其缺点的，比如，使用遇程会产生氟化氩（hydrogen fluorideo本文将回顾哈龙灭火剂的灭火原理及使用中的一些相关问题，然後讨论七氟丙烷的化学分解遇程、灭火原理以及在使用遇程中减少氟化氢产生的添加剂妁工作原理。本文亦将简要介绍将水雾冷却系统（waterspray coolingsystem，WSCS）与七氟丙烷灭火剂结合以减少氟化氢产生的设想，同时会论及如何定义更好的添加剂的标准。     

沙漠地区输电线路铁塔基础抗拔机理模型试验及分析

对达拉特～丰镇输电线路工程的铁塔基础做了模型试验 ,测试了土中位移、破坏形式、土中应力分布 ,应用软件ALGORFEAS ,得出了土体上拔时的应力场分布 ,并提出了强度机理及极限上拔力的计算方法。