废旧金属回收冶炼的辐射监测管理探讨

剖析了两起发生在废旧金属回收冶炼中的典型放射性污染事故,在分析放射性废旧金属来源和我国现状的基础上,提出了废旧金属回收冶炼的辐射监测应当进行分级管理和加强口岸辐射监测,以及目前亟待解决的几个问题。     

γ辐照装置退役环境影响评价要求

2011年环境保护部发布了《放射性同位素与射线装置安全和防护管理办法》,进一步明确了γ辐照装置退役环境影响评价的内容。本文介绍了γ辐照装置退役项目的环境影响评价要求,并就实践中的情况提出了几个建议。     

Characterization and Preparation of Ce-Zr-O Solid Solution

ＣｅｒｉｕｍｏｘｉｄｅｗｉｔｈＣａＦ2 ｓｔｒｕｃｔｕｒｅｉｓｃｕｒ ｒｅｎｔｌｙｂｅｉｎｇｕｓｅｄａｓａｐｒｏｍｏｔｅｒｉｎｏｘｉｄａｔｉｏｎ .ＴｈｅｃａｐａｂｉｌｉｔｉｅｓｏｆｔｈｅｒｅｄｏｘｃｏｕｐｌｅＣｅ4 Ｃｅ3 ａｒｅｓｔｒｏｎｇｌｙｅｎｈａｎｃｅｄｉｆｏｔｈｅｒｅｌｅｍｅｎｔｉｓｉｎｔｒｏ ｄｕｃｅｄｉｎｔｏＣｅＯ2 ｌａｔｔｉｃｅｂｙｆｏｒｍｉｎｇｓｏｌｉｄｓｏｌｕ ｔｉｏｎ .ＳｅｖｅｒａｌａｐｐｒｏａｃｈｅｓｈａｖｅｂｅｅｎｕｓｅｄｔｏｐｒｅｐａｒｅＣｅＯ2 ＺｒＯ2 ｍｉｘｅｄｏｘｉｄｅ…     

冷镦钢SWRCH22A炼钢工艺优化研究

主要介绍了首钢水钢冷镦钢SWRCH22A炼钢生产工艺优化的改造实践。针对冷镦钢SWRCH22A工艺存在钢水回si现象严重、可浇性不稳定的问题采取相应的优化工艺措施,通过生产工艺的优化,水钢生产的SWRCH22A钢水回si量由开发初期的平均0．04％降至平均0．02％,连浇炉数由2炉提高至7炉。生产节奏和品质明显提升。     

Simulations of NBI fast ion loss in the presence of toroidal field ripple on EAST

NBI fast ion losses in the presence of the toroidal field ripple on EAST have been investigated by using the orbit code GYCAVA and the NBI code TGCO. The ripple effect was included in the upgraded version of the GYCAVA code. It is found that loss regions of NBI fast ions are mainly on the low field side near the edge in the presence of ripple. For co-current NBIs, the synergy effect of ripple and Coulomb collision on fast ion losses is dominant, and fast trapped ions located on the low field side are easily lost. The ripple well loss and the ripple stochastic loss of fast ions have been identified from the heat loads of co-current NBI fast ions. The ripple stochastic loss and the collisioninduced loss are much larger than the ripple well loss. Heat loads of lost fast ions are mainly localized on the right side of the radio frequency wave antennas from the inside view toward the first wall. For counter-current NBIs, the first orbit loss due to the magnetic drift is the dominant loss channel. In addition, fast ion loss fraction with ripple and collision for each NBI linearly increases with the effective charge number, which is related to the pitch angle scattering effect.     

DNA‐Directed Gold Nanodimers with Tunable Sizes and Interparticle Distances and Their Surface Plasmonic Properties

A quantitative understanding of the localized surface plasmon resonances (LSPRs) of metallic nanostructures has received tremendous interest. However, most of the current studies are concentrated on theoretical calculation due to the difficulty in experimentally obtaining monodisperse discrete metallic nanostructures with high purity. In this work, endeavors to assemble symmetric and asymmetric gold nanoparticle (AuNP) dimer structures with exceptional purity are reported using a DNA self‐assembly strategy through a one‐step gel electrophoresis, which greatly facilitates the preparation process and improves the final purity. In the obtained Au nanodimers, the sizes of AuNPs (13, 20, and 40 nm) and the interparticle distances (5, 10, and 15 nm) are tunable. The size‐ and distance‐dependent plasmon coupling of ensembles of single, isolated dimers in solution are subsequently investigated. The experimental measurements are correlated with the modeled plasmon optical properties of Au nanodimers, showing an expected resonance shift with changing particle sizes and interparticle distances. This new strategy of constructing monodisperse metallic nanodimers will be helpful for building more complicated nanostructures, and our theoretical and experimental understanding of the intrinsic dependence of plasmon property of metallic nanodimer on the sizes and interparticle distances will benefit the future investigation and exploitation of near‐field plasmonic properties.     

Ionic Colloidal Molding as a Biomimetic Scaffolding Strategy for Uniform Bone Tissue Regeneration

Inspired by the highly ordered nanostructure of bone, nanodopant composite biomaterials are gaining special attention for their ability to guide bone tissue regeneration through structural and biological cues. However, bone malformation in orthopedic surgery is a lingering issue, partly due to the high surface energy of traditional nanoparticles contributing to aggregation and inhomogeneity. Recently, carboxyl‐functionalized synthetic polymers have been shown to mimic the carboxyl‐rich surface motifs of non‐collagenous proteins in stabilizing hydroxyapatite and directing intrafibrillar mineralization in‐vitro. Based on this biomimetic approach, it is herein demonstrated that carboxyl functionalization of poly(lactic‐co‐glycolic acid) can achieve great material homogeneity in nanocomposites. This ionic colloidal molding method stabilizes hydroxyapatite precursors to confer even nanodopant packing, improving therapeutic outcomes in bone repair by remarkably improving mechanical properties of nanocomposites and optimizing controlled drug release, resulting in better cell in‐growth and osteogenic differentiation. Lastly, better controlled biomaterial degradation significantly improved osteointegration, translating to highly regular bone formation with minimal fibrous tissue and increased bone density in rabbit radial defect models. Ionic colloidal molding is a simple yet effective approach of achieving materials homogeneity and modulating crystal nucleation, serving as an excellent biomimetic scaffolding strategy to rebuild natural bone integrity.     

C/C复合材料摩擦磨损性能研究

综述了国内外对C/C复合材料摩擦磨损性能的研究现状.指出C/C复合材料的摩擦磨损机理为机械磨损和氧化磨损,在高温下(500℃以上)C/C复合材料的磨损是机械磨损和氧化磨损共同作用的结果,而氧化是磨损的根本原因;影响C/C复合材料摩擦磨损性能的因素有材料本身的因素,如复合材料的热解炭结构、密度、石墨化度、防氧化涂层等,也有实际操作条件的因素如刹车环境、刹车过程中的刹车速度、刹车能量等.提出对不同工艺制备的C/C复合材料的摩擦磨损性能有待于进一步研究.     

G-M制冷机与振动样品磁强计的耦合试验

为了测量样品在低温(20 K)下的磁性材料的各个参数性能,实验台采用双级G-M制冷机直接冷却气氛室,利用氦气的自然对流传热来达到冷却样品的目的.振动样品磁强计(VSM)与G-M制冷机的耦合实验实现了低温条件下样品的磁性能的测定.介绍该实验台的设计过程和耦合实验结果.     

快速凝固/粉末冶金高硅铝合金微观组织及拉伸性能

采用快速凝固／粉末冶金法制备Al-17Si-6Fe-4.5Cu-0.5Mg合金,并进行T6处理。利用现代测试手段对挤压态及T6处理态合金微观组织及拉伸性能进行研究。结果表明：采用这种工艺可使合金组织中第二相得到显著细化,经T6处理后第二相有粗化趋势,同时也有新相沉淀析出;合金拉伸性能主要表现在高温、低塑性及良好耐热性。