自动单道γ谱仪

本文介绍自动扫描,自动打印的单道γ谱仪的电路结构和工作原理,给出其主要性能和测试结果。     

Synthesis and characterization of monodispersed BaSO4/Y2O3:Eu3+ core–shell submicrospheres

Spherical BaSO₄ particles have been coated with Y₂O₃:Eu³⁺ phosphor layers (BaSO₄/Y₂O₃:Eu³⁺) by the wet chemical method. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dipersive spectroscopy (EDS), photoluminescence spectra were utilized to characterize the BaSO₄/Y₂O₃:Eu³⁺ core–shell-structured phosphor particles. The obtained core–shell phosphors consist of well dispersed submicron spherical particles with narrow size distribution. XRD result shows that no reaction occurred between the BaSO₄ cores and the Y₂O₃:Eu³⁺ shells even after annealing at 1400 °C. TEM and EDS results show that BaSO₄ particles are well coated with the shell of Y₂O₃:Eu³⁺. The BaSO₄/Y₂O₃:Eu³⁺ core–shell particles show a red emission corresponding to ⁵D₀?⁷F₂ of Eu³⁺ under the excitation of ultraviolet.     

激光驱动靶丸超高速发射研究

本文通过理论模拟和实验相结合的方法,对激光驱动靶丸超高速发射以及超高速靶丸撞击防护材料进行研究。首先利用辐射流体程序HYADES对靶的飞行速度进行了理论模拟预估,其次在中国工程物理研究院神光Ⅲ原型装置上开展实验验证,得到了将直径200 μm的铝球加速至44 km/s的实验结果,完成了高速铝球与防护材料撞击测试,并通过撞击形态验证了该材料的防护效果。本研究在模拟在轨航天器空间碎片撞击与防护方面具有十分重要意义。     

中国水产食品质量及安全控制研究进展

随着经济全球化的深入发展和食品贸易的不断扩大,中国水产食品加工业发展非常迅速,其质量和安全性已成为影响大众消费和工业健康可持续发展的关键因素,引起社会的广泛关注。为了充分掌握现阶段中国水产食品的质量安全控制状况,以便有效控制水产品的质量安全,本文对我国水产食品及质量安全控制现状、国外的先进质量控制技术和监管体系进行分析,并在对我国水产食品目前存在的问题进行总结的基础上,提出改善水产食品质量及安全控制的建议和改进措施。     

一株产共轭亚油酸乳酸菌的筛选和鉴定

从酸菜汁中分离到一株具有较高产共轭亚油酸(CLA)能力的乳酸菌菌株9#,在小麦胚芽培养基中发酵CLA产量达到64.28μg/mL.通过菌株菌落形态学特征、菌体形态学特征、菌株生化特征和细菌16S rDNA进行的同源性比对,利用MEGA4软件构建系统发育树,表明菌株9#属于干酪乳杆菌(Lactobacillus casei).     

Graphitic nanorings for super-long lifespan lithium-ion capacitors

Porous graphitic carbon nanorings (PGCNs) are proposed by smart catalytic graphitization of nano-sized graphene quantum dots (GQDs). The as-prepared PGCNs show unique ring-like morphology with diameter around 10 nm, and demonstrate extraordinary mesoporous structure, controllable graphitization degree and highly defective nature. The mechanism from GQDs to PGCNs is proven to be a dissolution-precipitation process, undergoing the procedure of amorphous carbon, intermediate phase, graphitic carbon nanorings and graphitic carbon nanosheets. Further, the relationship between particles size of GQDs precursor and graphitization degree of PGCNs products is revealed. The unique microstructure implies PGCNs a broad prospect for energy storage application. When applied as negative electrode materials in dual-carbon lithium-ion capacitors, high energy density (77.6 Wh·kg⁻¹) and super long lifespan (89.5% retention after 40,000 cycles at 5.0 A·g⁻¹) are obtained. The energy density still maintains at 24.5 Wh·kg⁻¹ even at the power density of 14.1 kW·kg⁻¹, demonstrating excellent rate capability. The distinct microstructure of PGCNs together with the strategy for catalytic conversion from nanocarbon precursors to carbon nanorings opens a new window for carbon materials in electrochemical energy storage.

     

基于中心对齐多核学习的稀疏多元逻辑回归算法

稀疏多元逻辑回归(SMLR)作为一种广义的线性模型被广泛地应用于各种多分类任务场景中。SMLR通过将拉普拉斯先验引入多元逻辑回归(MLR)中使其解具有稀疏性,这使得该分类器可以在进行分类的过程中嵌入特征选择。为了使分类器能够解决非线性数据分类的问题,该文通过核技巧对SMLR进行核化扩充后得到了核稀疏多元逻辑回归(KSMLR)。KSMLR能够将非线性特征数据通过核函数映射到高维甚至无穷维的特征空间中,使其特征能够充分地表达并最终能进行有效的分类。此外,该文还利用了基于中心对齐的多核学习算法,通过不同的核函数对数据进行不同维度的映射,并用中心对齐相似度来灵活地选取多核学习权重系数,使得分类器具有更好的泛化能力。实验结果表明,该文提出的基于中心对齐多核学习的稀疏多元逻辑回归算法在分类的准确率指标上都优于目前常规的分类算法。     

圆形重力式深水网箱受灾破坏机理分析

我国沿海地区台风等海洋灾害性气候高发,重力式深水网箱易受到台风等恶劣海洋环境的严重威胁,严重阻碍了我国网箱养殖产业发展。重力式深水网箱受灾破坏形式主要包括浮架受损、网衣严重变形和锚碇脱锚。以温州南麂岛海域的网箱设施情况和水文资料为样本,选取了周长分别为40,60 m及80 m的圆形重力式深水网箱,在水深20,22 m及23 m,波高4~10 m,周期5.4~12.5 s时,通过计算网箱在波浪作用下的水动力响应,利用BP神经网络构建受灾破坏因子与结构受损的定量关系,并利用灰色关联度识别受灾破坏主控因子。分析结果表明,BP神经网络方法可以很好地拟合自变量(受灾破坏因子)与应变量(结构受损)的定量关系。在锚绳破坏中,波高的关联系数为0.59,波高为主控因子;在网衣变形中,周长的关联数为0.39,周长为主控因子;在浮架受损中,周长的关联数为0.58,周长为主控因子。     

Template‐Mediated Assembly of DNA into Microcapsules for Immunological Modulation

There is a need for effective vaccine delivery systems and vaccine adjuvants without extraneous excipients that can compromise or minimize their efficacy. Vaccine adjuvants cytosine–phosphate–guanosine oligodeoxynucleotides (CpG ODNs) can effectively activate immune responses to secrete cytokines. However, CpG ODNs are not stable in serum due to enzymatic cleavage and are difficult to transport through cell membranes. Herein, DNA microcapsules made of CpG ODNs arranged into 3D nanostructures are developed to improve the serum stability and immunostimulatory effect of CpG. The DNA microcapsules allow encapsulation and co‐delivery of cargoes, including glycogen. The DNA capsules, with >4 million copies of CpG motifs per capsule, are internalized in cells and accumulate in endosomes, where the Toll‐like receptor 9 is engaged by CpG. The capsules induce up to 10‐fold and 20‐fold increases in tumor necrosis factor (TNF)‐α and interleukin (IL)‐6 secretion, respectively, in RAW264.7 cells compared with CpG ODNs. Furthermore, the microcapsules stimulate TNF‐α and IL‐6 secretion in a concentration‐ and time‐dependent manner. The immunostimulatory activity of the capsules correlates to their intracellular trafficking, endosomal confinement, and degradation, assessed by confocal and super‐resolution microscopy. These DNA capsules can serve as both adjuvants to stimulate an immune reaction and vehicles to encapsulate vaccine peptides/genes to achieve synergistic immune effects.