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

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

Research progress on the objectification, quantitation and standardization of tongue manifestation in traditional Chinese medicine

舌诊是中医诊断学的重要组成部分,舌象在中医临床治疗中具有重要的诊断意义与辨证价值。传统中医舌象易受主客观因素影响,难以客观化、定量化、标准化,严; 重制约舌象临床应用及发展。随着医学、计算机等现代技术的迅猛发展,中医舌象客观量化研究取得了长足进步,并被应用于基础及临床研究。文章对近几年中医舌; 象采集分析系统、舌象定量化研究、现代仪器应用与舌象基础研究进行概述,为舌象应用于临床治疗提供客观、科学的思路与方法。Tongue diagnosis is an important part of traditional Chinese medicine; (TCM), and the tongue manifestation is also important in the diagnosis; and syndrome differentiation in TCM clinical treatment. However, due to; the lack of objective, quantitative and standardized valuation, with it; being susceptible to subjective and objective factors, the application; and development of traditional tongue diagnosis is limited for a long; period. Recently, with the rapid development of medical and other modern; technology, the objectification, quantitation and standardization of TCM; tongue manifestation have been received great progress, including the; progress in basic and clinical researches. Recent researches on the; tongue image acquisition and analysis system, the quantitation of tongue; manifestation, the application of modern instruments and the basic; research in tongue manifestation were reviewed to provide certain; objective and scientific ideas and methods for TCM tongue manifestation.教育部新世纪优秀人才支持计划; 中国博士后科学基金面上项

科学认识与精准把握新时代我国社会主要矛盾的转变

科学判定中国发展的历史方位和主要矛盾,是制定正确的党的基本理论、基本路线、基本方略的前提。新时代我国社会主要矛盾转变的科学判断,符合中国社会主要矛盾发展的历史逻辑和实践逻辑,具有鲜明的时代特色,实现了理论与实践的辩证统一,是社会基本矛盾分析法的创造性应用。解决新时代中国社会的主要矛盾,必须牢牢坚持中国共产党的领导,必须长期坚持并不断发展习近平新时代中国特色社会主义思想,必须继续推进全面深化改革事业。国家社会科学基金一般项目“全球视野下中国话语体系建构与中国话语权提升研究”(16BKS093);;厦门大学马克思主义理论“一流学科”建设项目的阶段性成

以人民为中心的发展思想的哲学基础

以人民为中心的发展思想既蕴含着尊重规律、按规律办事的实践逻辑,又彰显了人民至上的价值取向,具有深厚的哲学基础。以人民为中心的发展思想是中国特色社会主义的鲜明特质,是对社会主义本质的中国表达,是对历史唯物主义人民是历史主体的思想的继承和发展,是对科学社会主义实现每个人自由而全面发展的价值旨归的当代追求,为新时代中国共产党做出经得起历史、实践和人民检验的实绩,提供了坚实的理论基础和明确的价值导向。2016年国家社科基金一般项目“全球视野下中国话语体系建构与中国话语权提升研究”(项目编号:16BKS093);;厦门大学马克思主义理论“一流学科”建设项目阶段成

凤眼莲对福建龙湖重金属的监测及其评价

通过测定龙湖不同区域的水生植物凤眼莲结果表明,凤眼莲对水体的zn、MO、Pb、Cu等都有较大的吸收富集能力。其根部富集能力略大于其茎叶部位。通过测定表明,龙湖在重金属污染方面基本上处于未污染状态至轻污染状态

双金属Zn-Fe金属有机框架的制备及其丙酮气敏特性研究

采用溶剂热法制备了双金属Zn-Fe金属有机框架结构(Zn-Fe MOF),利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)和X射线衍射仪(XRD)对其微观形貌和晶相进行表征分析。结果表明:制备的双金属Zn-Fe MOF为纳米球结构,其直径约为150 nm。同时,制备了基于双金属Zn-Fe MOF材料的气体传感器件,研究了其对丙酮的气敏特性。测试结果表明:基于双金属Zn-Fe MOF的气体传感器对丙酮的最佳工作温度为210℃。在最佳工作温度下,对浓度为1×10-6的丙酮气体响应可达到2,响应/恢复时间分别为6 s/13 s,且具有较好的重复性和长期稳定性。最后,对基于双金属Zn-Fe MOF气体传感器的气敏机理进行了讨论。国家自然科学基金项目(51205274);;山西省人才专项项目(2016[36]);;山西省自然基金项目(2016[39]);;山西省高校科技创新研究项目(2016[37]);;山西省归国留学择优项目([2014]95);;山西省归国留学基金项目(2013-035);;山西省科技重大专项项目(20121101004);;山西省高等学校特色重点学科建设项目(晋教财[2012]45号

DNA barcoding of hydromedusae in northern Beibu Gulf for species identification

水螅水母类是浮游动物群落的重要组成部分,在近岸海洋生态系统物质循环和能量流动中扮演着重要角色。水螅水母类形态结构简单,但其物种的准确鉴定一直是分类工作中的难点。dnA条形码极大地促进了水螅水母物种的快速、准确鉴定。本研究扩增了北部湾北部28种水螅水母的线粒体COI和16S序列,分别为92条和116条;比较了2个基因片段的种内、种间k2P(kIMurA 2-PArAMETEr)遗传距离;构建了基于这2个基因片段的系统发育邻接树(nEIgHbOr-JOInIng PHylOgEnETIC TrEE);并结合矢量分析构建了klEE-dIAgrAM图。结果显示:COI序列的种内遗传距离为0.008±0.005(0–0.033),种间遗传距离为0.298±0.128(0.092–0.597);16S序列的种内遗传距离为0.006±0.010(0–0.047),种间遗传距离为0.394±0.195(0.068–0.898)。2个基因序列在所调查种类中,种内遗传差异均小于种间遗传差异,存在明显的条形码间隔(bArCOdIng gAP)。基于2个基因片段的nJ树均显示,单种所有个体都位于同一独立分枝。研究结果表明,以COI和16S作为dnA条形码均能对北部湾北部常见水螅水母类进行物种鉴定。Being a major component of coastal zooplankton assemblages, hydromedusae play a key role in material recycling and energy flow of marine ecosystems.Species identification is challenging for this group due to their phonetic simplicity.DNA barcoding provides an efficient method for species identification.In the present study, 92 COI and 116 16 S sequences from 28 hydromedusae species were amplified.A neighborjoining phylogenetic tree was constructed based on Kimura 2-parameter genetic distance and further studied using Klee-diagram vector analysis.Intra-specific K2 P genetic distance averaged 0.008±0.005(0–0.033) for COI, and 0.006±0.010(0–0.047) for 16S; inter-specific K2 P genetic distance averaged 0.298±0.128(0.092– 0.597), and 0.394±0.195(0.068–0.898) for COI and 16 S, respectively.An obvious "barcoding gap" was detected for all species in both markers and all individuals of a species clustered together in both the COI and 16 S trees.Further confirmatory evidence was also provided through indicator vector analysis.Hence, both COI and 16 S appear to be accurate and efficient markers for hydromedusae identification in northern Beibu Gulf.国家自然科学基金青年科学基金(41006078); 海洋公益性行业专项(201005012-3;201005015-5); 厦门大学中央高校基本科研业务费专项资金(2010121037); 厦门大学海洋科学基地科研训练及科研能力提高项目(J1210050