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21.
为了制备一种以四氧化三铁磁性纳米粒子为壳、聚苯乙烯为核的新型高分子功能材料,并有望应用于磁稳定流化床反应器,采用悬浮聚合法制备了四氧化三铁纳米粒子包覆聚苯乙烯的磁性微球。运用扫描电镜(SEM)、红外光谱(FT-IR)、振动样品磁强计(VSM)、热失重(TGA)等测试手段,分析并表征了磁性聚苯乙烯微球的形貌特征、粒径、磁学性能及四氧化三铁包覆量。实验结果表明,所得磁性聚苯乙烯粒子为球状微球,粒径为150~200 μm且分布较窄;磁性聚苯乙烯微球的四氧化三铁包覆量达到7.81%(质量分数),最高饱和磁化强度为3.97 A·m2/kg。 相似文献
22.
通过高温煅烧法对粉煤灰进行活化,采用酸浸法浸取活化后粉煤灰中的镓。研究了煅烧条件(助剂种类、助剂含量、煅烧温度、煅烧时间)对粉煤灰中镓的浸出效果的影响。采用X射线衍射表征粉煤灰以及不同煅烧条件下所得产物的物相组成,用ICP测定了浸取液中的镓的含量。研究结果表明:在3种助剂(碳酸钠、碳酸钙和氧化钙)中,碳酸钠是粉煤灰活化的最优助剂;碳酸钠与粉煤灰的质量比为1.5∶1、煅烧温度为800 ℃、煅烧时间为120 min时,粉煤灰中镓的浸出量(质量分数)为5.262×10-5。 相似文献
23.
In this paper, a new nanostructure is proposed, namely, the knitted graphene-nanoribbon sheet (KGS), which consists of zigzag and/or armchair graphene nanoribbons. The knitting technology is introduced to graphene nanotechnology to produce large area graphene sheets. Compared with pristine graphene, the chirality of a knitted graphene-nanoribbon sheet is much more flexible and can be designed on demand. The mechanical properties of KGSs are investigated by molecular dynamics simulations, including the effect of vacancies. With hydrogen atoms saturating the ribbon edges, the structure (KGS + H) is found to be of significant mechanical robustness, whose fracture does not rely on the critical bonds. The fracture strain of KGS + H remains nearly unchanged as long as there remains a single defect-free graphene nanoribbon in the tensile direction. This graphene nano knitting technique is experimentally feasible, inspired by a recent demonstration by Fournier et al. [Phys. Rev. B, 2011, 84, 035435] of lifting a single molecular wire using a combined frequency-modulated atomic force and tunnelling microscope. 相似文献
24.
The barium titanate–molybdenum composites were prepared through solid state reaction method in argon atmosphere. The microstructure, resistivity, and dielectric properties of the composites were investigated. XRD results indicated that chemical reactions between barium titanate (BaTiO3:BT) and molybdenum (Mo) have taken place during sintering, resulting in the formation of BaMoO4 (BM) and BaTi2O5 (BT2). The resistivity decreased with the increasing amount of Mo in the composites. The composites (when x = 5 and 20 wt.%) showed lower dielectric constant than pure BaTiO3, especially, the dielectric constant (when x = 20 wt.%) reached a minimum value (<104), while composites (when x = 10 and 15 wt.%) showed rather high dielectric constant at temperatures range from 25 °C to 160 °C. The dielectric constant of the composite gradually decreased with increase in frequency at the room temperature. The dielectric constant of composite (when x = 5 wt.%) comes up to 104, and the Tc (Curie temperature) of the composite was relatively higher than that of BT (120 °C). 相似文献
25.
邵永平 《电信工程技术与标准化》2011,(9):19-22
本文通过对目前试验网中LTE无线网络与核心网络间网络组织,以及无线侧IP地址分配方案的分析,并且进行多种方案的比较,最后提出安全性和可扩展性更好的方案. 相似文献
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介绍了国家重大科学工程项目--兰州重离子加速器冷却存储环(HIRFL-CSR)的实验环(CSRe)以及RIBLLⅡ的子系统--实时数据交互系统.该系统主要实现对前端电源设备的实时同步控制,具体的实现方法是从控制Web界面输入的前端控制设备所需的数据信息传送至中心Orade数据库,再更新至前端服务器的Orade数据库,随后传送至ARM板中的sqlite数据库,给DSP板提供输入数据信息,通过同步触发事例对电源设备进行同步实时控制.该系统正在RIBLLⅡ的测试中,运行正常、可靠性强、性能稳定. 相似文献
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An ultrasound indentation system for biomechanical assessment of soft tissues in vivo was developed. The pen-size, hand-held probe was composed of an ultrasound transducer and a load cell. The ultrasound transducer was at the tip of the probe serving also as the indentor. The thickness and deformation of the soft tissue layer were determined from the ultrasound echo. A compressive load cell was connected in series with the ultrasound transducer to record the force response. A validation experiment was performed on porcine tissues. Force and deformation acquired with the present system was in good comparison with those obtained from a Housfield material testing machine. Material constants were obtained via a curve-fitting procedure by predicting the force transient response from the deformation-time data using a quasilinear viscoelastic model. In addition, deformation in the fat and in the muscle could be differentiated. The potential applications of this type of indentation probes are many. The specific application of this current development is for stump tissue assessment in the design of prosthetics 相似文献