Vibration Damping of Carbon Nanotube Assembly Materials

Vibration reduction is of great importance in various engineering applications, and a material that exhibits good vibration damping along with high strength and modulus has become more and more vital. Owing to the superior mechanical property of carbon nanotube (CNT), new types of vibration damping material can be developed. This paper presents recent advancements, including our progresses, in the development of high-damping macroscopic CNT assembly materials, such as forests, gels, films, and fibers. In these assemblies, structural deformation of CNTs, zipping and unzipping at CNT connection nodes, strengthening and welding of the nodes, and sliding between CNTs or CNT bundles are playing important roles in determining the viscoelasticity, and elasticity as well. Towards the damping enhancement, strategies for micro-structure and interface design are also discussed

厌氧条件在不同Fe( II) 浓度测定方法中必要性的比较研究

厌氧是目前Fe(II)测定方法中常选择的处理方式,但是不可避免会给实验操作带来不便。为了方便、准确地测定铁还原体系中的Fe(II)浓度,对比研究了厌氧条件对草酸—草酸铵和盐酸两种典型浸提方法测定Fe(II)浓度的影响。结果表明:对于草酸—草酸铵浸提法,厌氧条件是必须的,以防止提取液中的Fe(II)被氧化,而且样品浸提1 h 便可用于Fe(II)的测定;然而对于盐酸浸提法,厌氧条件却并不是必须的,对Fe(II)浓度测定基本不产生影响。因此,为简化实验操作或在没有厌氧条件的情况,可利用盐酸浸提法测定铁还原体系中Fe(II)浓度

Droplet Microfluidics and Its Application in Chemical Biology

液滴微流控是在微流控芯片上发展起来的一种操纵微小体积液体的全新技术。近年来，随着液滴操控技术的发展与成熟，微流控液滴系统已经成为一个在微观尺度上进行化学和生物学研究的重要平台，并成功应用到蛋白结晶、酶分析、化学合成、单分子/单细胞研究等分子与细胞生物学及分析化学研究领域中。在传统的液滴微流控技术基础上，本文将“油包水”改成“油包琼脂糖”，并提出了一种琼脂糖液滴微流控技术。以微流控芯片上琼脂糖液滴的生成和优化，及其在化学生物学中的应用为目标，探索了微流控芯片的加工，构筑了芯片的基本元件——微阀和微泵，摸索了琼脂糖液滴的产生条件，在传统油包水液滴PCR（聚合酶链式反应）基础上提出了一种琼脂糖液滴P...Microfluidic droplet is a novel technology based on microfluidic chip that can manipulate ultra-small volume of sample. In recent years, research in droplet-based microfluidics has made great progress. Various techniques concerning the generation and manipulation of droplets have been developed. Droplet based microfluidics systems has become an important platform for microscale chemical and biolog...学位：理学博士院系专业：化学化工学院化学系_化学生物学学号：2052009015330

Wide-Range Tunable Dynamic Property of Carbon Nanotube-Based Fibers

Carbon nanotube (CNT) fiber is formed by assembling millions of individual tubes. The assembly feature provides the fiber with rich interface structures and thus various ways of energy dissipation, as reflected by the non-zero loss tangent (>0.028--0.045) at low vibration frequencies. A fiber containing entangled CNTs possesses higher loss tangents than a fiber spun from aligned CNTs. Liquid densification and polymer infiltration, the two common ways to increase the interfacial friction and thus the fiber's tensile strength and modulus, are found to efficiently reduce the damping coefficient. This is because the sliding tendency between CNT bundles can also be well suppressed by the high packing density and the formation of covalent polymer cross-links within the fiber. The CNT/bismaleimide composite fiber exhibited the smallest loss tangent, nearly as the same as that of carbon fibers. At a higher level of the assembly structure, namely a multi-ply CNT yarn, the inter-fiber friction and sliding tendency obviously influence the yarn's damping performance, and the loss tangent can be tuned within a wide range, as similar to carbon fibers, nylon yarns, or cotton yarns. The wide-range tunable dynamic properties allow new applications ranging from high quality factor materials to dissipative systems

Bio-Inspired Aggregation Control of Carbon Nanotubes for Ultra-Strong Composites

High performance nanocomposites require well dispersion and high alignment of the nanometer-sized components, at a high mass or volume fraction as well. However, the road towards such composite structure is severely hindered due to the easy aggregation of these nanometer-sized components. Here we demonstrate a big step to approach the ideal composite structure for carbon nanotube (CNT) where all the CNTs were highly packed, aligned, and unaggregated, with the impregnated polymers acting as interfacial adhesions and mortars to build up the composite structure. The strategy was based on a bio-inspired aggregation control to limit the CNT aggregation to be sub 20--50 nm, a dimension determined by the CNT growth. After being stretched with full structural relaxation in a multi-step way, the CNT/polymer (bismaleimide) composite yielded super-high tensile strengths up to 6.27--6.94 GPa, more than 100% higher than those of carbon fiber/epoxy composites, and toughnesses up to 117--192 MPa. We anticipate that the present study can be generalized for developing multifunctional and smart nanocomposites where all the surfaces of nanometer-sized components can take part in shear transfer of mechanical, thermal, and electrical signals

On the Coarse Embeddability of l_p-Spaces Into l_2

对l(_P-)空间与l_2之间粗嵌入关系作进一步的研究,证明了度量空间X可粗嵌入进l_2当且仅当存在某个20 such that X can be coarsely embedded into {l_p,2<p≤p_0} uniformly.This gave an equivalent condition for the coarse embeddability of metric spaces into l_2.国家自然科学基金(11101340;11201160); 福建省自然科学基金(2010J05012;2012J05006); 华侨大学高层次人才科研启动项目(11BS223

Comparison of fertilizer-effect models on winter wheat response to nitrogen and phosphorus fertilizers in saline soils in the Yellow River Delta

通过大田试验, 研究了黄河三角洲盐碱土地区冬小麦合适的肥料效应模型。在冬小麦生长季设置4种不同的氮磷肥用量, 根据&ldquo;3414&rdquo;试验设计8 种不同的肥效试验处理, 以探讨线性加平台、一元二次、平方根和二元二次4 种不同模型的拟合效果。结果显示, 4 种肥料效应模型的拟合结果经检验都达到极显著水平 (P&lt;0.01)。在一元肥料效应模型中, 氮磷一元二次模型拟合效果最好, 最高收益分别为7 448.3 元&middot;hm-2 和7 357.7 元&middot;hm-2, 最佳经济氮磷用量分别为254.4 kg&middot;hm-2 和98.6 kg&middot;hm-2。对比一元与二元模型, 后者拟合效果较好, 最佳经济氮磷用量分别为244.1 kg&middot;hm-2 和94.2 kg&middot;hm-2, 即氮磷肥配比为2.6∶1, 经济效益为7 432.4 元&middot;hm-2, 氮肥农学利用率为6.2 kg(籽粒)&middot;kg-1(N), 磷肥农学利用率为13.8 kg(籽粒)&middot;kg-1(P2O5)。结合拟合度、最佳经济施肥量、经济收益、肥料农学利用率和一元模型的局限性分析得出, 二元二次肥料效应模型最优, 可作为黄河三角洲地区盐碱土冬小麦氮磷肥效模型的最佳选择。</p

Application of XML in Parameters Processing of Software for NMR

本文针对NMR(核磁共振)系统软件的需求为其参数文件提供了一种XML设计方案,通过对多种XML解析方案的实验和比较,为XML参数文件提供了一种最优的解析和处理方案(VTD-XML),并且论证了VTD-XML在大数据处理方面的优势。According to the commands of parameters processing in software for NMR, the authors provided an approach with XML for the parameters file, and brought forth a best solution(VTD-XML) for XML processing by comparing it with others techniques of XML parsing.Lastly they draws a conclusion that VTD-XML is more appropriate for large XML document than others similar techniques.国家科技支撑计划课题(2006BAK03A22