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

Diet composition of Difflugia tuberspinifera( testate amoeba) based on a clone library technique

瘤棘砂壳虫是东亚特有的原生动物,广泛分布于长江与珠江中下游以及福建地区的湖泊和水库,作为水生态系统的捕食者,在维持水生态系统的结构与功能方面发挥着重要作用。利用18S rrnA基因PCr扩增和克隆文库测序等分子生物学技术方法,从基因水平研究瘤棘砂壳虫的食物组成。结果表明:所获得的46条序列在97%相似度水平含有11类OTuS(OPErATIOnAl TAXOnOMIC unITS,操作分类单元),其中包括轮虫6个,桡足类5个,说明瘤棘砂壳虫的捕食类群以轮虫和桡足类为主,同时也证明单细胞生物可以直接以多细胞的后生动物为食。此外,通过克隆文库测序技术分析原生动物的食物组成比例,不仅是一种方便、高效、快速,重复性高的方法,同时也为分析原生动物的生态功能提供了一种新的视角。Difflugia is a morphologically diverse genus of the free-living shelled amoeboid protozoa that are important components of freshwater ecosystems and play crucial roles in nutrient cycles and energy flow through food webs.Difflugia tuberspinifera is an endemic species of East Asia and is widely distributed in freshwater lakes and reservoirs in China.Clearly,this species plays a critical role in maintaining the structure and function of freshwater ecosystems.However,little is known about its diet composition and predatory behavior at both species and gene levels.This testate amoeba( D.tuberspinifera) was first found in the Wujiang River,Guizhou Province,China.Subsequently,more detailed studies on its morphology and biometry have been done on natural populations from Yangtze River and Pearl River valleys,and Fujian reservoirs.Recently,Han et al.illustrated that D.tuberspinifera is an active and agile hunting carnivore that can capture swimming prey including micro-particulates,rotifers,and other metazoans.In previous studies,however,the specimen identifications were done by microscopic examination,which requires a broad and deep taxonomic knowledge and is verylaborious,time-consuming,and somewhat variable because of insufficient taxonomic resolution.In order to facilitate the identification of diet composition in D.tuberspinifera,an inexpensive,efficient,rapid and easy-to handle gene clone library has been developed for diet detection and analysis.The plankton samples were collected from the Hubian Reservoir in Xiamen city in September of 2010.Individual cells were isolated using a glass capillary under an inverted microscope and washed 3—5 times with distilled water before DNA extraction and PCR amplification.The 18 S rRNA gene was amplified by the universal eukaryotic primers,and the purified PCR products were ligated into the p GEM-T vector and transformed into Escherichia coli DH5α-competent cells.In total,46 plasmids containing target gene fragments were successfully identified and sequenced.Each sequence was compared with sequences available in the Gen Bank database using BLAST,and the closest relatives were identified for diet or food composition analysis.Finally,11 OTUs( operational taxonomic units) were identified at 97% sequence similarity level,and they belonged to either Rotifera( 52%) or Copepoda( 48%).Our results,combined with existing data,suggested that:1) the diet composition of Difflugia tuberspinifera is composed of both rotifera and copepoda species;2) unicellular protozoa are not only the food of metazoa,but they can also prey on multicellular micro-metazoa;3) molecular methods are universally applicable,and the SSU rRNA( small subunit ribosomal RNA) gene clone library is an efficient,rapid,and repeatable approach to study the diet composition of protozoa.国家自然科学基金项目(31172114;30800097); 福建省杰出青年科学基金项目(2012J06009

一个基于格的环签名方案的改进

针对Wang等提出的基于格中困难问题的环签名方案不满足不可伪造性的问题,提出了一种改进的环签名方案.该方案在随机谕言模型下满足全密钥暴露下的匿名性和内部攻击下的不可伪造性.而且使用一种强陷门生成算法,保证了新的签名方案简单、高效且容易实施.国家自然科学基金(11261060

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

基于证券实验室的会计专业相关课程教学改革研究

由厦门大学会计发展研究中心提供的第四届会计与财务问题国际研讨会——会计教育改革与发展论文集中的第二部分：教学研究10随着科学技术的进步，目前会计专业的教育观念、人才培养模式、教学内容、教学方法和手段凸显滞后。改革教学方法和手段，加强学生获取知识的能力和创新精神的培养，是深化高等学校会计专业教学改革的重要内容，对提高教学效率、保证教学质量具有重要意义。本课题正是基于这样的背景，在证券实验室的环境下从课程设置、教学方式和师资教育等方面探讨新的会计类课程的教学模式。 会计类课程的教学方法改革，主要体现在演示教学、交互探讨式教学和模拟现实教学；会计的教学手段创新，建立会计模拟作账实验室、会计电算化实验室、会计及相关课程的模拟交易实验室和开发会计教学软件等。本课题研究针对我国高等教育会计专业教学中存在的会计专业课程设置过细、教学方式单一、会计模拟实践教学硬件落后和师资缺乏等问题，基于证券模拟实验室的功能开发和项目建设，提出课程设置的调整方案，建立以“公共基础课＋专业理论课（专业基础课、专业课）＋专业实践课＋公共选修课”的课程设置基本模式，重新整合课程内容体系，以模拟试验室为基础建立课程“套餐”，以多媒体教学推进教学方式的改革。证券模拟实验室为科研提供所需的大批数据，科研所需的检验论证直接通过模拟实验室模拟运行，通过这种“教学+科研”的形式组织学生进行科研实验，在提升教师素质的同时，增强学生的专业素质和科研能力

类泛素蛋白及其中文命名

泛素家族包括泛素及类泛素蛋白,约20种成员蛋白.近年来,泛素家族领域取得了迅猛发展,并已与生物学及医学研究的各个领域相互交叉.泛素家族介导的蛋白质降解和细胞自噬机制的发现分别于2004和2016年获得诺贝尔奖.但是,类泛素蛋白并没有统一规范的中文译名. 2018年4月9日在苏州召开的《泛素家族介导的蛋白质降解和细胞自噬》专著的编委会上,部分作者讨论了类泛素蛋白的中文命名问题,并在随后的\"泛素家族、自噬与疾病\"(Ubiquitinfamily,autophagy anddiseases)苏州会议上提出了类泛素蛋白中文翻译草案,此草案在参加该会议的国内学者及海外华人学者间取得了高度共识.冷泉港亚洲\"泛素家族、自噬与疾病\"苏州会议是由美国冷泉港实验室主办、两年一度、面向全球的英文会议.该会议在海内外华人学者中具有广泛影响,因此,参会华人学者的意见具有一定的代表性.本文介绍了10个类别的类泛素蛋白的中文命名,系统总结了它们的结构特点,并比较了参与各种类泛素化修饰的酶和它们的生物学功能.文章由45名从事该领域研究的专家合作撰写,其中包括中国工程院院士1名,相关学者4名,长江学者3名,国家杰出青年科学基金获得者18名和美国知名高校华人教授4名.他们绝大多数是参加编写即将由科学出版社出版的专著《泛素家族介导的蛋白质降解和细胞自噬》的专家

1978～2008年中国湿地类型变化

分别基于美国陆地卫星(Landsat MSS/TM/ETM+)和中巴资源卫星(CBERS-02B)影像数据,以人工目视解译为主,完成了中国1978～2008年4期(基准年分别为1978,1990,2000和2008年)湿地遥感制图,并进行了大量的室内外验证.在此基础上,对我国湿地现状及近30年来湿地变化进行了初步分析,得到以下主要结论:(ⅰ)截止2008年,中国湿地面积约为324097km2,其中以内陆沼泽(35%)和湖泊湿地(26%)为主.(ⅱ)1978～2008年,中国湿地面积减少了约33%,而人工湿地增加了约122%.过去30年里湿地减少的速度大幅降低,由最初5523km2/a(1978～1990年)降为831km2/a(2000～2008年).(ⅲ)减少的自然湿地(包括滨海湿地和内陆湿地),其类型变化由湿地向非湿地转化的比例逐渐降低.初期(1978～1990年)几乎全部(98%)转换为非湿地;在1990～2000年间减少的自然湿地约有86%转化为非湿地,而在2000～2008年,这一比例下降为77%.(ⅳ)气候变化和农业活动是中国湿地变化的主要驱动因素,湿地变化在中国分为三大不同特征区域,即西部三省/自治区(西藏、新疆和青海)、北部两省/自治区(黑龙江和内蒙古)和其他省市区.其中西部区域尤其是青藏高原,湿地变化的驱动因子以气候增温为主;新疆湿地由于气候增温和农业活动共同作用造成变化不大.北部省/自治区的湿地变化则主要由农业活动引起;而其他省市区的湿地变化几乎完全受控于人类的农业经济活动

Empirical Analysis of Guangxi Talent Demand Forecast Based on BP Neural Network

BP神经网络具有较好的非线性拟合能力、较强的自学习自适应,论文运用BP神经网络模型解决人才需求预测问题。首先介绍BP神经网络模型构建,其次确定人才需求预测影响指标,应用BP神经网络模型预测广西2018—2020年科技人才需求量,最后对广西人才培养与发展提出建议。The BP neural network has better nonlinear fitting ability and stronger self-learning and self-adaptive ability. Paper using BP neural network model to solve the problem of talent demand forecasting. First,it introduces the construction of BP neural network model. Secondly, it confirms the prediction index of talent demand, and predicts the demand of science and technology talents in Guangxi from 2018 to 2020 by using the BP neural network model. Finally, it puts forward suggestions on talent cultivation and development for Guangxi provice.广西软科学课题广西创新创业人才激励机制及政策研究,项目批准号:桂科AB1645001