稀释剂粉末压片-X射线荧光光谱法测定锑矿石中锑及主量组分

利用X射线荧光光谱仪结合稀释剂粉末压片法来测定锑矿石中锑及主量组分。通过稀释剂的加入,减弱了样品的基体效应。人工配制了一系列具有浓度梯度的样品来解决标准样品个数偏少的问题。方法简便、实用,具有较高的精密度和准确度,测定结果满足实际工作需要。方法的相对标准偏差(RSD)为0.19%～2.0%,与常规分析结果基本一致。     

Decreased Resting-State Functional Complexity in Elderly with Subjective Cognitive Decline

Individuals with subjective cognitive decline (SCD) are at high risk of developing preclinical or clinical state of Alzheimer’s disease (AD). Resting state functional magnetic resonance imaging, which can indirectly reflect neuron activities by measuring the blood-oxygen-level-dependent (BOLD) signals, is promising in the early detection of SCD. This study aimed to explore whether the nonlinear complexity of BOLD signals can describe the subtle differences between SCD and normal aging, and uncover the underlying neuropsychological implications of these differences. In particular, we introduce amplitude-aware permutation entropy (AAPE) as the novel measure of brain entropy to characterize the complexity in BOLD signals in each brain region of the Brainnetome atlas. Our results demonstrate that AAPE can reflect the subtle differences between both groups, and the SCD group presented significantly decreased complexities in subregions of the superior temporal gyrus, the inferior parietal lobule, the postcentral gyrus, and the insular gyrus. Moreover, the results further reveal that lower complexity in SCD may correspond to poorer cognitive performance or even subtle cognitive impairment. Our findings demonstrated the effectiveness and sensitiveness of the novel brain entropy measured by AAPE, which may serve as the potential neuroimaging marker for exploring the subtle changes in SCD.     

Rapid and Efficient Separation of Oil from Oil‐in‐Water Emulsions Using a Janus Cotton Fabric

A novel bi‐functional Janus cotton fabric is used to separate oil from oil‐in‐water emulsions. This fabric is superhydrophobic on one surface and polyamine‐bearing on the other. When used as a filter, the polyamine‐bearing side causes the micrometer‐sized oil droplets to coalesce. The coalesced oil then fills fabric pores on the superhydrophobic side and selectively permeates it. Oil separation using this method is rapid and the separated oil is pure. Furthermore, the content of the model oil hexadecane (HD) in water after a separation can be reduced to less than 0.03±0.03 vol %. These features demonstrate the practical potential of this technology.     

基于全反射的发光二极管-照明光纤耦合器的设计与研制

光纤照明由于具有成本低、安全性高、便携性好和装饰性强等优势,已经逐渐进入了人们的视野。然而,现阶段的光源[特别是发光二极管(LED)]由于辐射发散角大,与照明光纤的耦合效率普遍较低。为了解决这个问题,根据全反射原理,设计并制作了一种LED-照明光纤耦合器。经过实验验证,该耦合器具有聚光性强、耦合效率高、体积小、制备简便和成本低等优点,是一种能够有效提升LED-光纤耦合效率的方式。     

碘杂环化合物的质谱研究

研究了碘杂环化合物质谱行为和电子碰撞诱导裂解途径.结果表明:3,6-二硝基-二苯并碘六环卤化物(Ⅰ、Ⅱ、Ⅲ)和3,6-二硝基-9-酮-二苯并碘六环卤化物(Ⅳ、Ⅴ、Ⅵ)的EI质谱是样品在仪器内热分解产物的混合质谱;吸附在样品上的溶剂甲酸参与了后者的热分解过程;电子碰撞诱导裂解产生的碎片离子2-卤-2′-碘-4,4′-二硝基-二苯酮(Ⅳ′、V′、Ⅵ′)是化合物Ⅳ、V、Ⅵ的主要热分解产物.     

尿素甲醛聚合反应中的沉淀现象

首次研究了尿素甲醛聚合反应中的沉淀现象以及不同反应条件对沉淀产物半结晶结构特征的影响. 定量分析结果显示以尿素甲醛物质的量之比1.0∶1.0为基础, 增加甲醛用量沉淀产物质量减少, 但当增加尿素用量时沉淀质量为一定值. 根据聚合产物线型结构对应的反应计算, 沉淀产物收率接近100%. 改变体系酸性和反应物总量等条件也可得到类似的定量反应结果. 沉淀产物中特征官能团的伸缩振动光谱随着反应条件的变化而变化. 当增加甲醛用量时, 官能团振动吸收强度明显减弱; 增加尿素用量时吸收强度略有增加. 改变体系酸性和反应物总量同样可对产物的振动光谱产生影响. 这种吸收强度的变化与XRD表征所得样品结晶性变化规律完全一致, 这表明尿素甲醛聚合反应中的沉淀现象是一种线型分子之间氢键相互作用引起的半结晶聚积过程.     

LaCl3对轮藻节间细胞吸收矿质元素的影响

稀土元素能够促进植物的生长发育,但其作用机制还不清楚。本文以珊瑚轮藻的节间细胞为实验材料,从单细胞水平研究了10μmol.L-1LaCl3处理对Mg,Ca,Mn,Fe,Cu,Zn和Mo 7种植物必需矿质元素在轮藻细胞壁和细胞内容物中浓度的影响。结果发现,La3 能够促进Ca,Mn,Zn和Fe的跨膜运输,而对其他3种矿质元素在细胞内的浓度没有显著影响。La3 处理还显著增加了细胞壁中Zn和Mn的水平,但降低了Ca和Mg的水平。其机制可能与La3 和Ca2 在细胞膜外的相互作用有关。     

Uptake and elimination of lanthanum by excised roots of <Emphasis Type="Italic">Triticum aestivum</Emphasis> L.

In this paper, uptake and elimination of lanthanum by excised roots of Triticum aestivum L. in various conditions were studied. Lanthanum concentrations in the roots were determined by neutron activation analysis. Results showed that the uptake of La in the excised root was almost independent of vitality, and the bonding of La with the roots was tight, but could be removed by EDTA treatment. There was significant dose-dependent accumulation of La in the excised roots within the experimental concentration (0–40 μmol/l).