低能N6+离子与Ne原子碰撞的单电子俘获研究

采用冷靶反冲离子动量谱仪技术,实验测量了能量为6和8.6 keV/u N6+-Ne碰撞的单电子俘获过程,得到了主量子数n分辨的态选择截面和炮弹离子的散射角分布。实验结果表明,单电子主要被俘获到n=3和n=4的态。这与分子库仑过垒模型计算的反应窗所预测的结果符合。同时,实验获得了单电子俘获到n=3和n=4量子态的角微分截面,此结果与经典模型的计算结果存在较大差别,主要原因是碰撞反应过程的多通道耦合效应。     

Ricci curvature,radial curvature and large volume growth

In this paper, we study complete noncompact Riemannian manifolds with Ricci curvature bounded from below. When the Ricci curvature is nonnegative, we show that this kind of manifolds are diffeomorphic to a Euclidean space, by assuming an upper bound on the radial curvature and a volume growth condition of their geodesic balls. When the Ricci curvature only has a lower bound, we also prove that such a manifold is diffeomorphic to a Euclidean space if the radial curvature is bounded from below. Moreover, by assuming different conditions and applying different methods, we shall prove more results on Riemannian manifolds with large volume growth.     

Z-P-S空间中一类非线性算子方程解的研究

本文利用Menger PN空间中半闭1-集压缩算子的拓扑度理论研究Z-P-S空间中非线性算子方程Ax=ux解的存在性问题,改进和推广了相关文献中的结果.最后,我们给出主要结果的一个具体应用.     

Fluorescent Silver Nanoclusters as Effective Probes for Highly Selective Detection of Mercury(II) at Parts‐per‐Billion Levels

Facile preparation of water‐soluble and fluorescent Ag nanoclusters (NCs) stabilized by glutathione at room temperature is described. Although the glutathione layer was introduced to prevent the silver nanoparticles from decomposition and increase their water solubility, this simple surface optimization resulted in surprisingly high efficiency of selective Hg²⁺ sensing, where the limit of detection (LOD) was as low as 10^?10 M (0.02 ppb, 0.1 nM ). This result revealed a simple and practical strategy for Hg²⁺ detection using fluorescent Ag NCs as sensor probe, with the lowest detecting limits reported to date.     

Krasnoselskii定理几种新的推广

利用随机不动点指数,研究了随机半闭1-集压缩算子方程的随机解,同时,从不同角度推广了著名的Krasnoselskii定理,得出若干新的结果.     

The Surface Area Preserving Mean Curvature Flow in Quasi-Fuchsian Manifolds

In this paper, we consider the surface area preserving mean curvature flow in quasi-Fuchsian 3-manifolds. We show that the flow exists for all times and converges exponentially to a smooth surface of constant mean curvature with the same surface area as the initial surface.     

半序概率度量空间中一类算子方程的可解性

半序方法是研究非线性算子方程问题的主要方法之一。利用概率度量空间中由泛函诱导的半序,在不同的压缩条件下,研究了非线性算子方程Lx=N(x,x)的可解性问题,所得结论推广和改进了有关文献中的一些结论。     

Non-injection and one-pot approach to CdSe: Eu<Superscript>3+</Superscript> hybrid nanocrystals with tunable photoluminescence from green to red

Europium ion-doped CdSe hybrid nanocrystals (CdSe:Eu³⁺ NCs) as a class of new luminescent materials have drawn increasing attention in recent years owing to their remarkable optical properties. In this paper, we report a facile method to prepare CdSe:Eu³⁺ NCs using oleic acid (OA) as the capping agent. With this non-injection and one-pot synthesized approach, the formation and surface passivation of CdSe:Eu³⁺ NCs are performed simultaneously and result in intrinsic luminescence. The as-prepared CdSe:Eu³⁺ NCs are characterized by transmission electron microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy (EDX). Their optical properties are also studied by UV–vis and photoluminescence spectra. Moreover, the effects of feed ratios and reaction temperatures on the optical properties are further investigated. The results show that the luminescent spectra of CdSe:Eu³⁺ NCs are tunable from green (490 nm) to red (630 nm) and gradually redshift with the increase of the nanoparticle size from 2.5 to 4.4 nm. Upon decoration with 2-thenoyltrifluoroacetone (TTA), the luminescence of europium ion drastically increases and efficient energy transfer from CdSe host to the europium ion is proposed. In addition, an MTT and apoptosis assay show CdSe:Eu³⁺ NCs have low cellular toxicity and could be used as fluorescence imaging for human epithelial type 2 (Hep-2) cells. These properties make CdSe:Eu³⁺ NCs a potential candidate for biological labeling, immunoassays, and optical sensing.

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Graphical abstract Stable and luminescent CdSe:Eu³⁺ hybrid nanocrystals were synthesized, and the luminescence is tunable from green to red by the variation of reaction temperatures and feed ratios. Moreover, CdSe:Eu³⁺ NCs show low cellular toxicity and could be used as fluorescence probes for Hep-2 cells.

     

超胞声子晶体板的轻量化设计与研究

由于局域共振型声子晶体板具有优秀的低频声学特性,相关的研究越来越丰富,但多为实验室环境下的研究,对其工程应用方面的轻量化研究存在不足.因此,本文以变电站低频噪声为应用背景,提出一种局域共振型声子晶体板轻量化设计方法.基于此方法,设计出一种针对变电站噪声频谱特性的轻量化超胞声子晶体板.研究发现,此声子晶体板在50 Hz和...     

Novel biomarker pipeline to probe the oxidation sites and oxidation degrees of hemoglobin in bovine erythrocytes exposed to oxidative stress

Research on biomarkers for protein oxidation might give insight into the mechanistic mode of oxidative stress. In the work present here, a novel pipeline was established to probe the oxidation mechanism of bovine hemoglobin (Hb) with its oxidation products serving as the biomarkers. Reactive oxygen species generated by irradiation were used to mimic oxidative stress conditions to oxidize Hb in bovine erythrocytes. After Hb extraction and digestion, oxidized peptides in the tryptic fragments were assigned by comparison with the extracted ion chromatography spectra of native peptide from the control sample. Subsequent tandem mass spectrometry analysis of these peptides proved that oxidation was limited to partially exposed amino acid residues (α‐Phe₃₆, β‐Met₁, β‐Trp₁₄, for instance) in Hb. Quantitation analysis on these oxidized peptides showed that oxidation degrees of target sites had positive correlations with the extended oxidation dose and the oxidation processes were also controlled by residues types. Compared with the conventional protein carbonyl assay, the identified oxidized products were feasibility biomarkers for Hb oxidation, indicating that the proposed biomarker pipeline was suitable to provide specific and valid information for protein oxidation. Copyright © 2015 John Wiley & Sons, Ltd.