压力诱导发光 未来可期

科技创新的根源是基于基础科学研究的提升,而“从0到1”的突破是需要长期的积累和灵感的。本文讲述了发现压力诱导发光这一新现象的思想和材料设计。     

Wettability and surface energy of parylene F deposited on PDMS

For the first time, the wettability and surface energy of parylene F were investigated. The results showed that parylene F had a hydrophobic surface with an eigen water contact angle of 104.7 ± 0.6°. We found that 3.5 μl probe liquid was an optimal value for the contact angle measurement of parylene F. Moreover, we found that the Lifshitz–van der Waals/acid–base approach was unsuitable for determining the surface energy of parylene F, whereas the Owens–Wendt–Kaelble approach and the limitless liquid–solid interface wetting system were compatible. The surface energy of parylene F was estimated to be 27.06 mJ/m² (Owens–Wendt–Kaelble) and 40.41 mJ/m² (Limitless liquid-solid interface wetting system). Furthermore, this investigation also provided a reference for the applications of empirical and physics-based semi-empirical approaches for the estimation of surface energy.     

CaLuBO4∶Tb^3+荧光粉的制备及发光性质

采用高温固相反应法合成了不同Tb^3+掺杂浓度的CaLuBO4∶xTb^3+荧光粉,研究了样品的晶体结构和发光性质。在紫外光激发下,样品的发射光谱由Tb3+离子的5D3→7FJ(J=6,5,4)和5D4→7FJ′(J′=6,5,4,3)特征发射组成,其中位于545 nm和554 nm附近的5D4→7F5跃迁发射强度最大。荧光粉的激发光谱是由位于紫外区的Tb3+的4f-5d和f-f跃迁构成的。研究了Tb3+浓度对样品发光性质的影响。测量并分析了CaLuBO4∶xTb^3+荧光粉的5D3能级和5D4能级荧光寿命。结果表明,CaLuBO4∶xTb^3+是一种适于紫外激发的新型黄绿光荧光粉。     

915 nm宽条形半导体激光器输出特性

为了研究温升对915 nm宽条形应变量子阱半导体激光器输出特性的影响,搭建了基于半导体制冷片(TEC)的双向温控平台对其进行了测试。首先,改变激光器的外表面温度,测量其在不同注入电流时的光功率和波长,并利用CCD相机测量其慢轴发散角。然后,利用计算机仿真软件对激光器的工作状态进行稳态模拟,从而获得了其对应的热分布情况,通过将模拟得到的数据与实验测量的结果进行比较,获得了两者趋于一致的结论:当热功率从2.1 W升高至20.0 W时,慢轴发散角从2.6°增大至5.0°,同时波长发生红移,热透镜焦距减小;激光器波长随温度变化关系的系数约为0.4 nm/℃,器件热阻为1.5 K/W。因此,为了同时获得高的输出功率和稳定的输出波长,有必要将激光器外表面温度精确控制在某一数值,否则波长将会发生漂移;此外,在设计制作高功率半导体激光器时,通过适当增加条宽并采用散热良好的封装结构,可以减小对慢轴发散角的影响。     

激光束散角复合控制技术

为了降低部分相干光光学系统设计的复杂度及成本,增加部分相干光应用的便捷性,提出了一种液晶空间光调制器的激光相干度及束散角复合控制方法。首先介绍了对激光光束进行相干度和束散角复合控制的基本理论和方法;然后分别设置了相干度和束散角检测实验,检测了本方法所调制激光光束的相干度和束散角的准确性。实验结果表明,采用液晶空间光调制器生成相干度为0.9 mm、束散角为7.5 mrad,以及相干度为1.5 mm、束散角为3.8 mrad的部分相干光束,其相干度与理论值相比误差在5%以内,其相干度均方根误差分别为0.027386和0.031314,峰谷值分别为0.084658和0.089103;其束散角与理论值相比误差在5%以内,其束散角均方根误差分别为0.022478和0.023186,峰谷值分别为0.081201和0.092130。可见,该方法可以实现高精度的相干度及束散角复合控制。     

核电池概述及展望

核电池具有能量密度高、工作稳定可靠、无需人工干预等优点，在需要长期稳定供电的场合具有独特优势，其中热转换式核电池(RTG)是技术最为成熟且应用最早的一类，而β辐射伏特效应核电池已有商业化案例。目前，在β辐射伏特效应核电池研究中存在着放射源自吸收效应浪费能量、转化效率低、换能器件辐射损伤严重等问题，而对于一个实际的核电池，由于放射源自身不断衰变的属性，导致源的成分及其活度随着时间而发生变化，最终影响核电池的电学性能，其影响程度需要加以深入研究。本文以时间轴的形式对核电池的发展进行了全面回顾，简要介绍多种主流类型核电池的原理和应用范围；对于β辐射伏特效应核电池，指出放射源的自吸收是其中的关键科学问题。对于使用63Ni和TiT₂放射源的核电池，给出了其电学性能随时间变化的规律；指出对于某一特定结构的β辐射伏特效应核电池设计，在前期的模拟优化环节中，精细计算是至关重要的；最后提出了将放射源与换能材料相结合、使用含有较重同位素的换能器件的设想，这些设想有利于解决放射源自吸收问题、提高核电池输出功率和减轻辐射损伤的影响。     

高精度半导体激光打标机F-θ镜头设计

为保证半导体激光打标机F-θ镜头的扫描质量，实现系统像高与扫描角的线性变化，需对F-θ镜头给予一定的畸变量，并使其满足等晕条件。分析F-θ镜头工作原理及像差要求，根据1 064 nm半导体激光打标机的光源成像要求选择合适的玻璃材料，合理分配每片透镜的光焦度，以保证等晕成像；根据F-θ镜头线性成像要求，计算系统总畸变量为1.6%，系统总畸变量为系统的实际桶形畸变与相对畸变量之和；在光学系统优化设计时，引入这两项优化参数，优化过程中观察系统成像变化情况。设计结果表明:系统MTF曲线接近衍射极限，F-θ镜头相对畸变小于0.36%，各视场均方根半径均小于艾里斑直径，并且整个系统70%的能量集中在直径为16 μm的圆内，系统总畸变量为1.58%，满足设计指标要求。     

The antidepressant effect of 4-hydroxybenzyl alcohol 2-naphthoate through monoaminergic,GABAergic system and BDNF signaling pathway

Abstract

Gastrodigenin, also known as 4-hydroxybenzyl alcohol (HBA), is one of the main components of Gastrodia elata, which is a perfect lead compound of natural products. In order to get new active compounds, we modified the structure of HBA through esterification with carboxylic acid, and got a series of derivatives in which 4-hydroxybenzyl alcohol 2-naphthoate (NHBA) showed stronger antidepressant activity than HBA. In this paper, we firstly evaluated the antidepressant activity of NHBA by tail suspension test (TST) and forced swimming test (FST). Then, we carried out the biochemical assay and western blot to determine its mechanism. The results displayed that NHBA could increase the content of serotonin, dopamine, norepinephrine, γ-aminobutyric acid, brain-derived neurotrophic factor (BDNF) and tropomyosin receptor kinase B (TrkB) in mice brain. It suggested that NHBA exhibited an antidepressant-like effect through monoaminergic system, GABAergic system and BDNF/TrkB signaling pathways.     

Superhard monoclinic BN allotrope in M-carbon structure

Superhard materials have always attracted people's interesting due to their extensive industrial applications. In this work, two reasonable superhard monoclinic allotropes of boron nitrides with space group of Cm have been designed based on previously proposed M-carbon structure using first-principles calculations. Our results show that Cm-BN-1 and Cm-BN-2 are dynamically stable, and they are direct semiconductors with bandgap of 2.69 and 3.90 eV, respectively. Moreover, they could be potential superhard materials with Vickers hardness of 58.0 and 60.4 GPa, respectively. This work provides insights for exploring new superhard boron nitrides materials.