Preparation and luminescent modulation of KGaSiO4:Eu3+ phosphors using for multiple anti-counterfeiting

Anti-counterfeiting technology is of great significance to information security. To obtain high-quality anti-counterfeiting materials, the developments of inorganic materials are crucial. In this paper, a series KGaSiO₄:xEu³⁺ phosphors with persistent luminescence, photoluminescence, and thermochromic have been successfully prepared and the application of quadruple anti-counterfeiting is realized. The X-ray diffraction and Rietveld refinement indicate that the phosphors are pure phase. With Eu³⁺ ions doping, the structure change, site occupancies, and color-tunable phenomenon are carefully investigated. Different from another Eu³⁺ doping phosphor, the emission of KGaSiO₄:0.2% Eu³⁺ phosphor changes with the excitation light in the region of 240 nm–306 nm. The emission color can be modulated with the surrounding temperature. Surprisingly, this phosphor can emit green afterglow light, which is attributed to the different luminescent properties of the matrix and doping of Eu³⁺ ions. The series of phosphors exhibit abundant luminescent properties. Based on their wavelength dependence, concentration quenching, long afterglow, and thermochromic properties, the KGaSiO₄:xEu³⁺ phosphors can be effective materials for quadruple-modal anti-counterfeiting devices.     

Inhibition of electric field on inception soot formation: A ReaxFF MD and DFT study

The attenuation of soot formation from polycyclic aromatic hydrocarbons during the fuel combustion process is important to human health and environmental pollution. This work studies the mechanism of inhibition soot formation process under electric field. The process of soot formation with the chemical bonding and physical stacking of PAHs nucleation was investigated under the influence of electric field by using ReaxFF molecular dynamics and density functional theory. MD simulation reveals that the electric field in 1 × 10⁻⁵–1 × 10⁻⁴ V/Å induces an alternation in dispersion and stacking of PAH cluster to inhibit the PAH nucleation. The electric field inhibits the dehydrogenation and C–C bond cracking of the initial PAH during chemical growth of PAHs. Due to instability of the 5–7 membered rings, there are fewer bonding sites for large graphite lamella growth. The elucidation of reaction enthalpy of dehydrogenation, dimer growth, and the binding energy of π-π stacking with different direction field, are explored using DFT. The computational work discloses the inhibition mechanism of electric field on PAH development. The characterization results obtained by scanning electron microscopy and the temperature-programmed oxidation shows the coke content and particle size can be reduced under the influence of electric field which validates the computational result. The scientific insights gained here is useful for understanding soot inhabitation phenomenon.     

Three-dimensional ordered microporous silica supported p-lanthanum ferrite and n-ceria as heterojunction photocatalyst to activate peroxymonosulfate for bisphenol a degradation

In this study, three-dimensional ordered microporous silica supported p-lanthanum ferrite and n-ceria (n-CeO₂@p-LaFeO₃/3DOM SiO₂) was successfully synthesized as a visible light-driven photocatalyst for activating peroxymonosulfate (PMS) to degrade Bisphenol A (BPA). In a wide pH range (2–12), the BPA degradation efficiency maintained at a high level, organic matter and natural inorganic ions had no significant negative impact. When the BPA concentration was as low as 2 mg·L⁻¹, the removal rate in 60 min still reached 95.56%, indicating that the novel photocatalyst has potential application in the treatment of trace pollutants. The pore confinement effects of catalysts and the synergistic effect between LaFeO₃ and CeO₂ result in the excellent photocatalytic performance. We proposed the possible mechanism of BPA degradation, specifically involving the recognition and generation mechanism of reactive oxygen species (ROSs), adsorption processes and diffusion processes. In summary, the novel n-CeO₂@p-LaFeO₃/3DOM SiO₂ would be a promising candidate photocatalytic material for practical sewage treatment.     

Effect of glassy bonding materials on the properties of LAS/SiC porous ceramics with near zero thermal expansion

Near zero thermal expansion porous ceramics were fabricated by using SiC and LiAlSiO₄ as positive and negative thermal expansion materials, respectively, bonded by glassy material. The coefficient of thermal expansion value of a desired porous composite can be easily controlled by choosing the appropriate ratios of the different phases. It was shown that some of LiAlSiO₄ was decomposed to LiAlSi₂O₆ and LiAlO₂, some of LiAlSiO₄ reacted with SiO₂ to form LiAlSi₂O₆ during sintering. With increasing the content of glassy materials, the reaction between LiAlSiO₄ and SiO₂ was accelerated. The Young's modulus increased due to the neck growth between the SiC grains. The 52.5 vol% LiAlSiO₄ (LAS)/SiC ceramics with ∼36% porosity had a combination of near zero coefficient of thermal expansion ∼0.39 × 10⁻⁶ K⁻¹ at room temperature and relatively high Young's modulus ∼59 GPa.     

顶空气相色谱法测定卷烟条和盒包装纸的苯系物

建立卷烟条和盒包装纸中多种苯系物的测定方法。采用顶空气相色谱法测定卷烟条和盒包装纸中的苯、甲苯、乙苯、二甲苯。用建立的方法对某卷烟厂卷烟纸样品进行测定,平均加标回收率为91.4%~105.4%之间,相对标准偏差小于3%,最低检出限为0.005~0.02 mg/m2。所建立的方法简便、快捷,具有较好的精密度与更低的检出限,可用于烟草行业卷烟条和包装纸中的苯系物的测定。     

有源层溅射温度对非晶铟镓锌氧薄膜晶体管电学特性的影响

The effect of active layer deposition temperature on the electrical performance of amorphous InGaZnO （a-IGZO） thin film transistors （TFTs） is investigated. With increasing annealing temperature, TFT performance is firstly improved and then degraded generally. Here TFTs with best performance defined as ＂optimized-annealed＂ are selected to study the effect of active layer deposition temperature. The field effect mobility reaches maximum at deposition temperature of 150℃ while the room-temperature fabricated device shows the best subthreshold swing and off-current. From Hall measurement results, the carrier concentration is much higher for intentional heated a-IGZO films, which may account for the high off-current in the corresponding TFT devices. XPS characterization results also reveal that deposition temperature affects the atomic ratio and Ols spectra apparently. Importantly, the variation of field effect mobility of a-IGZO TFTs with deposition temperature does not coincide with the tendencies in Hall mobility of a-IGZO thin films, Based on the further analysis of the experimental results on a-IGZO thin films and the corresponding TFT devices, the trap states at front channel interface rather than IGZO bulk layer properties may be mainly responsible for the variations of field effect mobility and subthreshold swing with IGZO deposition temperature.     

舒展原理及应用

在一个完美的生产过程中，很少会需要舒展，纸幅会保持均匀平直。现实情况非常不同，绝大多数的成幅材料在处理过程中需要舒展，以防止或去除折皱，扩展幅面或在复卷分切过程中分开。成形网和干网的舒展是属于较少的无端材料的舒展情况。笔者在工作过程中发现国内纸厂的工程师和纸机操作人员普遍对它的机理不太了解甚至误解，这样不利于它的选型、操作和维护。因此基于工作的便利组织了此文。本文旨在介绍相关知识，启发思维，提高生产力。     

High near-infrared photoluminescence quantum efficiency from PbS nanocrystals in polymer films

We investigate the effect of film morphology and phase segregation in polymer/colloidal PbS nanocrystal films on the near-infrared photoluminescence quantum efficiency (PLQE) of the nanocrystals. A direct correlation between the size of closed packed nanocrystal phase separated domains and lower PLQE was established. Films with a near-infrared PLQE of up to 12% have been prepared.     

焊接顺序对中厚板对接焊残余应力的影响

针对同种材料,但几何结构不同的中厚板结构件之间的对接焊,运用有限元软件进行模拟,分析多层多道焊各层焊缝的焊接顺序对焊缝区域横、纵向残余应力的影响。采用内生热的加载方式模拟热源,采用生死单元法模拟多层多道焊缝的焊接过程。模拟结果表明,从几何尺寸小的一边向几何尺寸大的一边焊,沿焊缝底部和顶部中心线方向产生的横纵向残余应力峰值最小;底层的几道焊缝的焊接顺序对焊缝底部和顶部中心线方向所产生的横纵向残余应力的影响不大。     

基于IDM的建筑智能化设计流程研究

虽然BIM技术在国内已经得到广泛的应用,但由于没有统一的行业标准,BIM技术产生的价值没有充分体现。本文主要针对BIM的流程标准,用IDM方法从软件解决方案的角度分析建筑智能化设计流程。绘制了基于BIM的协同设计流程图,用相应的表格列出流程图中的活动内容和部分交换需求,并对MVD中的部分内容进行基于IFC的数据描述。在帮助设计人员明确本专业设计任务,提高设计效率的同时,为行业BIM标准的编制提供一定的参考。