照明配电末端分支回路导体截面的选择

针对现行照明配电设计中末端分支回路导体截面的选择普遍偏大问题，结合有关规范标准．对与导体截面选择有关的各因素进行分析，提出在绝大多数情况下，将照明配电末端分支回路绝缘铜导体截面从2．5mm^2改为1．5mm^2，可以节约大量的铜材．是符合节能减排原则的举措。     

Effects of pyrolysis temperature on the chemical composition of refined softwood and hardwood lignins

The current study uses nuclear magnetic resonance, Fourier-transform infrared spectroscopy and Raman spectroscopy to investigate the evolution of refined softwood and hardwood lignins under various pyrolytic exposures. Little chemical change occurred at pyrolysis temperatures of 250 and 300 °C, whereas significant mass loss and chemical change was observed at 400 and 500 °C. These losses were mainly attributed to evolution of methoxyl, hydroxyl, and propyl groups. Mass loss plateaued following pyrolysis at 500 °C, but rearrangements continued to occur at higher temperatures, resulting in char that became increasingly polyaromatic in nature. Following brief pyrolytic exposures at 500 and 600 °C, the refined hardwood and softwood lignins yielded coal-like products. Lignin pyrolyzed at higher temperatures yielded chars with greater order, similar in composition to coke. These coal and coke-like products are called “lignin-based carbon” (LBC). The polyaromatic nature of the LBC after high temperature pyrolysis was perceived as the result of radical formation and recombination, leading to fused aromatic structures, which occurs more readily at higher temperatures.     

Deep-blue thermally activated delayed fluorescence emitter with a very high fluorescence rate

Conventional thermally activated delayed fluorescence (TADF) molecules achieve small energy differences between the lowest singlet and triplet excited states (ΔE_ST) by enhancing the intramolecular charge transfer, which inevitably leads to a wide emission spectrum and low fluorescence rate. Here, we prepared a deep blue TADF molecule via a small ΔE_ST pyridine-phenol fluoroboron complex as the acceptor. The small ΔE_ST is maintained when carbazole donors are attached to the 4-position of the phenyl rings in the fluoroboron complex. Benefiting from the strong electron coupling between the donor (D) and acceptor (A) moieties, the compound Cz-4-BF exhibits a high fluorescence rate of 4.8 × 10⁸ s⁻¹ and a small D-A dihedral angle change in the excited state. Consequently, a photoluminescence (PL) quantum yield of nearly 100% and a PL spectrum with full-width at half-maximum (FWHM) < 60 nm were obtained in solution and low-concentration doped films. A TADF-sensitized fluorescence (TSF) device containing Cz-4-BF achieves an external quantum efficiency of 21%, which is higher than the devices employing classical fluorescent emitters and multiple resonance-type TADF emitters. The Cz-4-BF-based TSF device shows significantly improved color coordinates of (0.14, 0.10) versus a control device without Cz-4-BF.     

The effect of the exposed crystal plane on the antioxidant activity of nanoceria

Previous reports have noted that exposed crystal planes could affect the antioxidant activity of nanocerias, although the synthesized nanocerias used in those studies had different exposed crystal planes, as well as different sizes and morphologies. In order to better understand the effect of the crystal planes on the antioxidant activity of the materials, two types of nanocerias with similar morphology and size distribution but different crystal planes were synthesized using the hydrothermal method (CeO₂–H) and the ultrasonic template method (CeO₂–U). The antioxidant activities of the nanocerias were further explored within different ·OH concentrations in the reaction system. The experimental results showed that there is an obvious difference in the antioxidant activity of the two types of nanocerias in the lower free radical concentration system due to the effects of exposed crystal planes. CeO₂–U, with more active crystal planes (100), had stronger antioxidant activity. However, with the increase in the ·OH concentration in the reaction system, the difference in the antioxidant activity of the two nanocerias decreased. This research will increase our understanding of the antioxidant activity of the exposed crystal planes on nanocerias.     

水平受荷桩的截面优化设计

运用有限单元法和梯度法 ,尝试性地对端承桩进行变截面优化设计 ,编制了相应程序 ;并以一人工挖孔灌注桩为例 ,计算比较截面优化前后的内力、挠度。计算结果表明 ,变截面桩可节省混凝土材料约 45 %。     

软土动剪切模量与微观孔隙结构试验研究

 为了从土体微观结构的角度定量地研究动剪切模量的性质和变化,利用共振柱试验,并借助电子显微镜及微观孔隙结构分析手段,对粤东重塑软黏土动剪切模量随动剪应变衰减规律与宏微观条件下土颗粒孔隙特性的关系进行分析。根据基于Davidenkov三参数模型的非线性回归分析和微观孔隙结构的参数计算分析,得到随固结应力增加,最大动剪切模量增大,连续介质中机械波波速增强;土体的宏观孔隙比降低;孔隙的层次增加,孔隙周长–面积分形维度值增加;孔隙的均一化程度增加,孔隙分形维度值减小。研究表明,Davidenkov模型中的初始参数、范围参数及速率参数与微观孔隙结构参数存在对应关系,为软黏土动力特性与微观结构关系的理论研究提供依据。     

非木材纤维制浆清洁生产技术方案备料与蒸煮工段

我国人多地少,森林资源相对匮乏,林纸一体化不能完全解决原料短缺问题,而同时我国非木材纤维原料很丰富,加强非木材纤维原料制浆造纸意义重大。以苇浆生产线备料和蒸煮工段为例,采用先进和清洁生产的工艺技术和设备,可以最大限度地实现物质和能量的综合循环使用,符合制浆造纸行业清洁生产评价指标体系和循环经济的要求。本文重点介绍了芦苇原料备料和蒸煮工段的清洁生产技术方案。     

导热纸（膜）的研究进展

电子产品日渐突出的散热问题,引起了人们对电子领域热管理的广泛关注。柔性导热材料具有高韧性、高弹性、高导热、灵活性等特性,可运用于柔性电子器件,轻、薄型电子设备,电池等领域,帮助解决其散热问题。纸张及薄膜具有良好的柔韧性、优异的加工性和厚度可调整性,是良好的柔性导热材料。本文概述了近年来导热纸（膜）的研究进展,对不同基材的导热纸进行了归纳分类和介绍,重点讨论了纤维素基导热纸的制备方法、导热性能、导热性能测试方法及机械性能。     

地下室顶板楼盖梁、板消防车荷载取值探讨

国内各设计人员在进行地下室顶板楼盖梁、板计算时对消防车等效均布荷载的取值差异较大。根据力学原理,分析了地下室顶板楼盖中各构件计算中对消防车荷载的合理取值,特别是梁、板计算时的分别取值,以做到更加经济合理。     

Emerging application of 3D-printing techniques in lithium batteries: From liquid to solid

There is rapid progress in the field of 3D printing technology for the production of electrodes, electrolytes, and packages of batteries due to the technique’s low cost, a wide range of geometries printable, and rapid prototyping speed by combining computer-aided design with advanced manufacturing procedures. The most important part of 3D printing applied in batteries is the printing of electrodes, electrolytes, and packages. These will affect the battery energy/power density. However, there are still several challenges that need to be overcome to print active and stable electrodes/electrolytes for energy storage systems that can rival that of the state-of-the-art. In this review, the printing materials, and methods for batteries from liquid to solid-state batteries are discussed and recent examples of this technique applied in high power/energy batteries are highlighted. This review for batteries will cover 3D printing technologies, printed cathode, and anode in conventional batteries, and printed solid-state electrolytes in solid-state batteries. The working principles, advantages, and limitations for solid-state batteries via the 3D printing method will be discussed before highlighting the printing materials for electrodes and electrolytes. We will then discuss how to modify the electrode and solid-state electrolyte to raise the electrochemical performance of solid-state batteries using 3D printing. Finally, we will give our insights into the future perspectives of this printing technique for fabricating batteries.