基于改进U-Net的量子点STM图像分割

为提升量子点图像分割精度,降低特征识别误差,提出一种基于改进U-Net的量子点图像分割方法.首先,在预处理阶段,设计了以色彩通道为权值的灰度化算法,以提升后续分割效果.其次,在STM图像分割部分,在原始U-Net结构上引入中间过渡层以均衡网络各层特征.而后,建立数据集,并通过实验对比不同分割算法的精确度、召回率、F-measure.最后,将分割算法应用于量子点的特征识别,并测试了不同分割方式对应用的影响.实验结果显示,改进灰度化方法保留细节信息丰富,明显提升了量子点分割精度;改进U-Net的平均精确率、召回率、F-measure相较原始网络分别提升了13.83%、2.16%、8.13%.同时,实验数据表明由于分割精度的提升,量子点数量、纵横比等特征参数的识别更加精确.     

醇热反应低温合成锰钴镍热敏薄膜

锰钴镍复合氧化物是一种具有半导体性质的热敏材料. 本文采用金属有机沉积技术于室温条件下、在Si衬底上沉积一定 厚度的Mn_1.74Co_0.72Ni_0.54O₄金属 有机化合物薄膜, 并通过醇热反应进行低温结晶化合成, 可得到Mn_1.74Co_0.72Ni_0.54O₄结晶薄膜. 通过X 射线衍射、场发射扫描电子显微镜 (FESEM) 以及阻温特性等测试方法表征, 讨论了醇热反应对锰钴镍热敏薄膜的物相结构、微观形貌以及电学性能的影响. X射线衍射图显示薄膜已出现尖晶石结构的特征峰. 电镜照片说明结晶薄膜的表面较为平整、孔隙率低. 阻温特性关系表明薄膜具有明显的负温度系数效应, 室温(≈27°) 电阻率约为303.13 Ω·cm. 关键词： 醇热反应 锰钴镍薄膜 热敏电阻 低温合成     

核物质对称能和重离子碰撞中径向流阈能的同位旋效应

基于同位旋相关的量子分子动力学模型，采用三种不同形式的对称势，研究了¹²⁴Sn+¹²⁴Sn和¹²⁴Ba+¹²⁴Ba对心碰撞时在三种不同对称势下的径向膨胀流，发现径向膨胀流阈能与所采用的对称能形式密切相关，表现出明显同位旋效应，预示着径向膨胀流阈能的同位旋相关性可作为对称能的灵敏探针. 关键词： 径向膨胀流阈能 同位旋效应 重离子碰撞 同位旋相关的量子分子动力学模型     

金属Zn液态结构变化的研究

利用ＴＢ模型给出的原子间相互作用势详细计算了不同温度下Ｚｎ的双体分布函数ｇ（ｒ），结果发现随着温度的不断降低，液态金属Ｚｎ的ｇ（ｒ）第一峰变得高而尖，第二峰由弱变强，说明了液态金属Ｚｎ的有序度随温度降低而不断增强；利用键对分析技术统计了液态金属Ｚｎ在不同温度下的键取向序参数、键对数。键取向序参数及键对数随温度的变化，进一步证明了低温液态的有序度高于高温液态，从而充分说明液态金属在不同温度下有不同的结构形式，而不像人们想象得那样杂乱无章。     

Controlling theoretically total absorption in hybrid-cavity resonator with one graphene monolayer outside cavity

Total absorption is realized theoretically in a graphene-outside-cavity resonator. The structure is composed of the FP-Fano hybrid resonance cavity. Changing the thickness of grating exciting Fano resonance, the absorption-mode number can be tuned effectively. For the focused double-mode absorption, the resonances behave insensitively with the variation of chemical potential of graphene. Varying the geometry of grating can control the coupling extent of two modes. Also, by manipulating the period number of two-side multilayers around graphene, the absorption, shift and number of modes are governed.     

Structure-Activity Relationship, Cytotoxicity and Mode of Action of 2-Ester-substituted 1,5-Benzothiazepines as Potent Antifungal Agents

Our studies examined the structural features responsible for the antifungal activity of 2-ethoxycarbonyl-1,5- benzothiazepine （7a）. Three series of 1,5-benzothiazepine derivatives were synthesized and screened for their antifungal activity. The results suggested that the ethoxycarbonyl group at the 2 position and the imine moiety on the seven-membered ring are essential for activity. The most potent of the synthesized analogues （7a, 7b） were further studied by evaluating their cytotoxicity and mode of action （for 7a）. The results showed that compounds 7a and 7b were relatively safe for BV2 cells, but compound 7a interfered with Cryptococcus neoformans cell wall integrity by increasing the chitinase activity. Therefore, compound 7a was considered safe as an antifungal agent for animal cells.