MgScH15: A highly stable cluster for hydrogen storage

Mg-Sc-H systems exhibit superior stability and high hydrogen storage capacity among the large class of magnesium-based hydrogen storage materials, but the underlying mechanisms for their outstanding hydrogen storage properties remain largely unexplored and require further investigation. Here, we have performed a comprehensive investigation on the structural evolution of MgScH_n (n = 10–20) clusters by unbiased Crystal structure AnaLYsis by Particle Swarm Optimization (CALYPSO) method combined with density functional theory (DFT) optimizations at the B3PW91/6-311 + G(d) level. Our results show that the MgScH₁₅ cluster with C_s symmetry is found to be the most stable cluster with good hydrogen storage capacity of 17.8 wt% due to the strong interaction among the 1s orbitals of the H atoms, the 2p orbitals of the Mg atom and the 3d orbitals of the Sc atom. The present findings are promising for further exploring novel hydrogen storage nanomaterials.     

基于光学成像技术的针灸镇痛机理研究

疼痛治疗是一个医学难题。虽然人们对痛觉感受机理的认识已达到细胞分子水平,但现代医学疗法对疼痛尤其是慢性疼痛的治疗仍无良策。针灸镇痛疗法因副作用小、疗效好而逐渐获得西方认可。尽管针灸镇痛在临床上得到了验证,但是其机理尚未明确。正电子发射断层扫描(PET)、单光子发射计算机断层扫描(SPECT)和功能核磁共振成像(fMRI)、免疫组织化学等技术已被应用于针灸镇痛机理的研究。然而,这些技术在分辨率或无损检测等方面存在局限性,限制了它们在针灸镇痛机理研究中的进一步应用。介绍了采用光学成像技术研究针灸镇痛的机理,其中重点评述激光扫描共聚焦显微成像术、光学相干层析成像术及活体动物光学成像术在针灸镇痛机理研究中的应用。     

代数对芳基苄醚树枝状酞菁硅(Ⅳ)光敏产生单线态氧的影响

光敏剂产生单线态氧的能力是评价其光动力活性的因素之一。采用2,5-二甲基呋喃为吸收剂,通过高效液相色谱法研究了1-3代硝基芳基苄醚树枝配体轴向取代酞菁硅(Ⅳ)单线态氧的生成速率、生成速率常数及量子产率。结果表明,轴向取代酞菁硅(Ⅳ)单线态氧的生成速率和生成速率常数均随着树枝代数的增加而逐渐增大,低代的树枝配体轴向取代酞菁硅(Ⅳ)的单线态氧量子产率较高,这可能与不同代树枝配体对酞菁核的位点分离有关。研究将为开发轴向取代酞菁硅(Ⅳ)配合物作为新型光敏剂提供重要的理论参考。     

Exploring a Stable and Dense 3D Lead Chloride Hybrid with Emission of Self-Trapped Excitons toward X-Ray Scintillation

The exceptional photophysical properties of 3D organic–inorganic lead halide hybrids (OILHs) endow their significant potential for usage in optoelectronics, which has sparked intense research on novel 3D OILHs and associated applications. However, constructing new 3D OILHs based on large organic cations suffers from tough challenges due to the limitation of the Goldschmidt tolerance factor rule, let alone further explorations of their practical applications. Herein, a brand-new 3D lead chloride hybrid, (1MPZ)Pb₄Cl₁₀·H₂O ( 1 , 1MPZ = 1-methylpiperazine) is reported, featuring a dense 3D lead chloride framework made of the corner-, edge-, and face-shared lead chloride polyhedra. 1 presents a broadband white light emission with a large Stokes shift and a nanosecond photoluminescence lifetime, which originates from radiative recombination of self-trapped excitons (STEs) induced by the highly distorted structure. Such a reabsorption-free and fast-decayed STEs emission coupling with the dense 3D architecture further enables 1 with effective X-ray scintillation with good sensitivity. Impressively, 1 also shows superior environmental and radiation stability. This study provides a new 3D OILH with appealing luminescence, not only expanding the 3D OILH family but also inspiring the exploitation of their optoelectronic applications.     

动态聚焦条件对脉冲CO2激光骨硬组织消融的影响

激光辐照生物组织消融过程中由于工作距离的变化引起的离焦现象对消融效果具有重要影响。以新鲜离体牛胫骨组织为实验样品,置于一维电动平移台上,移动速度为5.5mm/s;脉冲CO2激光(10.64μm)平行光束经一可移动聚焦透镜后垂直辐照样品表面,光斑直径为200μm。实验时通过移动聚焦透镜位置改变焦点位置,实现消融过程动态聚焦。激光辐照功率为6W,脉冲频率为420Hz,水喷雾协同工作,喷水速度为5.5mL/min。辐照后,利用扫描电镜观察消融凹槽微结构,用光学相干层析成像(OCT)技术测量消融凹槽深度。结果表明,动态聚焦条件可显著提高消融速率,消融深度随等效脉冲数增加而增加,消融速率呈减小趋势;在动态聚焦条件下获得的消融凹槽的表面形貌和微结构较离焦条件下更不规则。     

材料特性对声光可调滤波器光谱分辨率的影响

声光可调谐滤波器(AOTF)是一种利用各向异性介质中的声光作用工作的快速可调谐的分光元件,通过调节所加载的超声波频率可实现对出射光波长进行灵活、快速地调节.光谱分辨率是评价声光可调滤波器性能的主要指标之一.以二氧化碲非共线声光可调滤波器为研究对象,基于声光作用基本原理,系统推导了非共线声光可调滤波器光谱分辨率公式,并分...     

非傍轴衍射光束的传输特性

基于小衍射源和衍射远场的特点,简化了瑞利-索末菲标量衍射积分公式,并应用于分析非傍轴衍射光束的衍射远场总功率和光束传输因子特性。由于物理概念上的空间频谱的定义域局限在一定范围,基于此计算的非傍轴衍射光束的衍射远场总功率不满足能量守恒定律,基于此计算的非傍轴衍射光束的光束传输因子也与常识不符。当采用数学概念上的空间频谱分析上述特性时,两个符合常识的规律被重提,并以非傍轴基模高斯光束衍射远场总功率和光束传输因子的相对计算误差说明上述结论。     

超短焦全景鱼眼镜头的研究与设计

着重分析了超短焦鱼眼镜头焦距与分辨率的关系,表明了像面尺寸一定的前提下焦距越短,全景展开的环景边缘分辨率越高。基于以上理念,依据超短焦全景镜头设计思路,设计了一款焦距像高比≤0.35,水平视场角 =360°,垂直视场角 ≥180°的全景鱼眼镜头。设计结果表明：在空间频率为 200 lp/mm处的 MTF值大于 0.4,接近衍射极限;在垂直半视场角 45°～90°的环景边缘区域拥有大于 75%的像素空间,使得环景展开后仍然具有较高的分辨率,从而代替多台不同方位的高解摄像机,实现高清全景监控。     

双路径反馈网络的图像超分辨重建算法

图像超分辨率重建在安防系统,小目标检测以及医学图像等有着广泛的应用.本文提出一种双路径反馈网络来提高图像超分辨重建的性能.在双路径网络中,一条路径采用深度残差稠密网络学习重建图像的高频信息,另一条路径直接在输入图像上通过亚像素卷积层上采样到所需分辨率来给重建图像提供低频信息,然后将两条路径得到的特征图进行融合来自适应的选取所需要的信息,接着通过一个反馈型卷积层进行局部循环训练来获得大的感受野.通过在数据集DIV2K上训练,实验结果表明所提方法的有效性和优越性.