Identification of the Angel-related elements in cyprinid fishes and their phylogenetic implications

Angel-related element belongs to the family of miniature inverted-repeat transposable elements (MITEs). In this paper we report the identification of an Angel-related element in the series Leuciscini of cyprinid fishes, which is located in the second intron of the growth hormone (GH) gene. We have also found that this element is absent in orthologous locus in the series Barbini of cyprinid fishes, that provides new evidence for the monophyly of the series Leuciscini. The insertion of Angel-related element into the GH gene might take place in the common ancestor of the series Leuciscini after its divergence from the series Barbini. The high sequence divergence and relatively broad species distribution of Angel-related elements implies that they might be ancient transposons which appeared about 26 million years ago.

A miniature insertion element transposable in Microcystis sp FACHB 854

A 186-bp sequence with imperfect terminal inverted repeats and target direct repeats but without any transposase-encoding capacity was found to be transposable in an isolate derived from Microcystis sp. FACHB 854. This miniature insertion element, designated as ISM854-1, and with its homologues present at least 10 copies in the genome of Microcystis FACHB 854, is inserted into the 8-bp long and AT-rich target sequences, but none or few in other Microcystis strains. A variant of ISM854-1, denoted ISM854-1A, has perfect inverted repeat sequences and may transpose in pairs in a structure like a composite transposon. This is the first report of non-autonomous transposition of a mini-IS in a cyanobacterium.

Parametric resonance for vibration energy harvesting with design techniques to passively reduce the initiation threshold amplitude

A vibration energy harvester designed to access parametric resonance can potentially outperform the conventional direct resonant approach in terms of power output achievable given the same drive acceleration. Although linear damping does not limit the resonant growth of parametric resonance, a damping dependent initiation threshold amplitude exists and limits its onset. Design approaches have been explored in this paper to passively overcome this limitation in order to practically realize and exploit the potential advantages. Two distinct design routes have been explored, namely an intrinsically lower threshold through a pendulum-lever configuration and amplification of base excitation fed into the parametric resonator through a cantilever-initial-spring configuration. Experimental results of the parametric resonant harvesters with these additional enabling designs demonstrated an initiation threshold up to an order of magnitude lower than otherwise, while attaining a much higher power peak than direct resonance. © 2014 IOP Publishing Ltd.

Free-space locomotion with thread formation

The paper presents a new concept of locomotion for wheeled or legged robots through an object-free space. The concept is inspired by the behaviour of spiders forming silk threads to move in 3D space. The approach provides the possibility of variation in thread diameter by deforming source material, therefore it is useful for a wider coverage of payload by mobile robots. As a case study, we propose a technology for descending locomotion through a free space with inverted formation of threads in variable diameters. Inverted thread formation is enabled with source material thermoplastic adhesive (TPA) through thermally-induced phase transition. To demonstrate the feasibility of the technology, we have designed and prototyped a 300-gram wheeled robot that can supply and deform TPA into a thread and descend with the thread from an existing hanging structure. Experiment results suggest repeatable inverted thread formation with a diameter range of 1.1-4.5 mm, and a locomotion speed of 0.73 cm per minute with a power consumption of 2.5 W. © 2013 IEEE.

Exploiting passive dynamics for robot throwing task

Throwing is a complex and highly dynamic task. Humans usually exploit passive dynamics of their limbs to optimize their movement and muscle activation. In order to approach human throwing, we developed a double pendulum robotic platform. To introduce passivity into the actuated joints, clutches were included in the drive train. In this paper, we demonstrate the advantage of exploiting passive dynamics in reducing the mechanical work. However, engaging and disengaging the clutches are done in discrete fashions. Therefore, we propose an optimization approach which can deal with such discontinuities. It is shown that properly engaging/disengaging the clutches can reduce the mechanical work of a throwing task. The result is compared to the solution of fully actuated double pendulum, both in simulation and experiment. © 2012 IEEE.

Trajectory control based on discrete full-range dynamics

There has been an increasing interest in the use of mechanical dynamics, (e.g., assive, Elastic, And viscous dynamics) for energy efficient and agile control of robotic systems. Despite the impressive demonstrations of behavioural performance, The mechanical dynamics of this class of robotic systems is still very limited as compared to those of biological systems. For example, Passive dynamic walkers are not capable of generating joint torques to compensate for disturbances from complex environments. In order to tackle such a discrepancy between biological and artificial systems, We present the concept and design of an adaptive clutch mechanism that discretely covers the full-range of dynamics. As a result, The system is capable of a large variety of joint operations, including dynamic switching among passive, actuated and rigid modes. The main innovation of this paper is the framework and algorithm developed for controlling the trajectory of such joint. We present different control strategies that exploit passive dynamics. Simulation results demonstrate a significant improvement in motion control with respect to the speed of motion and energy efficiency. The actuator is implemented in a simple pendulum platform to quantitatively evaluate this novel approach.

Measurement of estrogen activity in two Chinese lakes

Estrogenic activities of samples from two Chinese lakes, Ya-Er Lake and Donghu Lake, were measured by in vitro recombinant yeast assay and found in both lakes polluted with industrial and domestic wastewater. In methanol extracts of lake water samples the estrogen-like activity was higher than in toluene extracts. These results have been inverted for solid samples. Furthermore, the EC50 value of the water samples was close to the original concentration in the lake.

Gene transfer into genomes of human cells by the sleeping beauty transposon system

The Sleeping Beauty (SB) transposon system, derived from teleost fish sequences, is extremely effective at delivering DNA to vertebrate genomes, including those of humans. We have examined several parameters of the SB system to improve it as a potential, nonviral vector for gene therapy. Our investigation centered on three features: the carrying capacity of the transposon for efficient integration into chromosomes of HeLa cells, the effects of overexpression of the SB transposase gene on transposition rates, and improvements in the activity of SB transposase to increase insertion rates of transgenes into cellular chromosomes. We found that SB transposons of about 6 kb retained 50% of the maximal efficiency of transposition, which is sufficient to deliver 70-80% of identified human cDNAs with appropriate transcriptional regulatory sequences. Overexpression inhibition studies revealed that there are optimal ratios of SB transposase to transposon for maximal rates of transposition, suggesting that conditions of delivery of the two-part transposon system are important for the best gene-transfer efficiencies. We further refined the SB transposase to incorporate several amino acid substitutions, the result of which led to an improved transposase called SB11. With SB11 we are able to achieve transposition rates that are about 100-fold above those achieved with plasmids that insert into chromosomes by random recombination. With the recently described improvements to the transposon itself, the SB system appears to be a potential gene-transfer tool for human gene therapy.

Quantum tunneling through planar p-n junctions in HgTe quantum wells

We demonstrate that a p-n junction created electrically in HgTe quantum wells with inverted band structure exhibits interesting intraband and interband tunneling processes. We find a perfect intraband transmission for electrons injected perpendicularly to the interface of the p-n junction. The opacity and transparency of electrons through the p-n junction can be tuned by changing the incidence angle, the Fermi energy and the strength of the Rashba spin-orbit interaction (RSOI). The occurrence of a conductance plateau due to the formation of topological edge states in a quasi-one-dimensional (Q1D) p-n junction can be switched on and off by tuning the gate voltage. The spin orientation can be substantially rotated when the samples exhibit a moderately strong RSOI.

Intrinsic spin hall effect induced by quantum phase transition in HgCdTe quantum wells

The spin Hall effect can be induced by both extrinsic impurity scattering and intrinsic spin-orbit coupling in the electronic structure. The HgTe/CdTe quantum well has a quantum phase transition where the electronic structure changes from normal to inverted. We show that the intrinsic spin Hall effect of the conduction band vanishes on the normal side, while it is finite on the inverted side. By tuning the Cd content, the well width, or the bias electric field across the quantum well, the intrinsic spin Hall effect can be switched on or off and tuned into resonance under experimentally accessible conditions.

The influence of substrate nucleation on HVPE-grown GaN thick films - art. no. 684105

Thick GaN films were grown on sapphire in a home-made vertical HVPE reactor. Effect of nucleation treatments on the properties of GaN films was investigated, including the nitridation of sapphire, low temperature GaN buffer and MOCVD-template. Various material characterization techniques, including AFM, SEM, XRD, CL and PL have been used to assess these GaN epitaxial films. It was found that the surface of sapphire after high temperature nitridation was flat and showed high density nucleation centers. In addition, smooth Ga-polarity surface of epitaxial layer can be obtained on the nitridation sapphire placed in air for several days due to polarity inversion. This may be caused by the atoms re-arrangement because of oxidation. The roughness of N-polarity film was caused by the huge inverted taper domains, which can penetrate up to the surface. The low temperature GaN buffer gown at 650 degrees C is favorable for subsequent epitaxial film, which had narrow FWHM of 307 arcsec. The epitaxial growth on MOCVD-template directly came into quasi-2D growth mode due to enough nucleation centers, and high quality GaN films were acquired with the values of the FWHM of 141 arcsec for (002) reflections. After etching in boiled KOH, that the total etch-pit density was only 5 x 106 cm(-2) illustrated high quality of the thick film on template. The photoluminescence spectrum of GaN film on the MOCVD-template showed the narrowest line-width of the band edge emission in comparison with other two growth modes.

匿名凭证与匿名口令认证技术研究

随着隐私保护越来越为人们所关注，对匿名认证技术的研究已经成为学术领域的一个热点。本文主要着眼于匿名认证中的匿名凭证与匿名口令认证密钥协商。 在对匿名凭证技术的研究中，本文重点分析了防止凭证出借与凭证匿名更新两个匿名凭证系统性质的实现。 凭证出借是指匿名凭证系统中，用户可以随意将自己的凭证与他人共享，从而使多人可以同时使用一个凭证。本文提出一种新的防止凭证出借方法，并给出一个具体的实现方案。该方法将凭证出借与用户隐私联系起来，通过凭证本身实现防止凭证出借。凭证匿名更新则是指凭证内容进行更新时，凭证颁发方只能知道变更的内容信息，不知道其他任何信息。本文提出一种新的实现方法，在原有凭证的基础上，用相对较少的计算量来实现对凭证内容的更新，使用户匿名得到一个新的凭证。 在对匿名口令认证密钥协商的研究中，本文首先提出了两个攻击方案：针对Shin等人的TAP(t≥2)协议的内部假扮攻击和针对TAP(t≥2)协议以及Viet等人的k-out-of-n APAKE协议的离线字典攻击。前者破坏了协议的认证性，内部攻击者可以假扮服务器与用户建立会话密钥。后者破坏了协议最基本的对口令的安全保护，使得内部攻击者可以离线猜测组内所有用户口令。然后，本文提出了一个新的两方的匿名口令认证密钥协商协议：NAPAKE，并在Square Computational Diffiee-Hellman困难假设以及Decision Inverted-Additive Diffie-Hellman困难假设下证明其安全性。同时，还进一步将其扩展为D-NAPAKE协议，以实现多方的匿名口令认证密钥协商，该协议可以抵抗上面的两个攻击。

回转窑热解处理废锌锰电池试验研究

我国电池生产量已经达到209亿节（2003年），多年来一直占据世界第一大电池生产国的地位，其中锌锰电池占大多数。废锌锰电池丢弃后，其中的重金属物质会逐渐渗透到地下，污染土壤和水体。重金属在生物体内富集，会使生物体致畸或致变。但同时，废锌锰电池中也含有大量有用的资源如锌、二氧化锰等。应对其进行回收利用，变废为宝。本文介绍了废锌锰电池回收处理的主要技术及研究进展，不同的处理技术回收废锌锰电池时的目标产物各不相同，但一般可分为以下几种：以单质形式回收锌、锰和汞；以合金的形式回收锌和锰；回收锌和二氧化锰；回收各金属元素制备复合微量元素肥料；回收锌、锰元素制备锰锌铁氧体；回收锌、锰元素制备硫酸锌和碳酸锰等。本文对一些废锌锰电池回收处理技术的优缺点从无害化程度、资源化程度、产品等级、工艺要求以及二次污染五个方面进行了分析和比较。在对国内外废锌锰电池回收处理技术进行分析比较的基础上提出了一种成本较低、可操作性较强的处理技术：先以干法除去废锌锰电池中的汞，然后以湿法除去其它的有害重金属并进一步加工制备有机螯合微量元素肥料。 本文以回转窑中物料停留时间的经验公式和传热学的知识设计和计算了回转窑的长度和内径尺寸、电热丝的功率以及外围的保温材料厚度等参数。用保温材料和润滑油相结合的方式对回转窑的连接部分实行密封。通过调整回转窑的转速和回转窑支架两端高度差的方式控制物料在回转窑中的停留时间，从而调节热解时间的长短。利用自动控制设备调节电热丝的功率从而调节试验中的热解温度。利用该回转窑在不同条件下对热解处理废锌锰电池进行了试验研究，热解过程中产生的尾气和颗粒物用一系列吸收液进行吸收和固定。 在热解试验中改变影响热解过程的三种因素：热解温度、热解时间和载气流速并按三因素四水平的正交方法安排试验。改变废锌锰电池热解过程中的热解温度、热解时间和载气流速三种因素进行正交试验并利用正交统计学的方法分析了这三种因素对热解除汞率的影响。利用ICP检测仪测定了各吸收液中汞的含量，并分析热解气体产物经过系列吸收液时汞被吸收的情况以及汞的形态分布。利用气相色谱仪对尾气成分进行了测定，并对热解过程中产气的过程和规律进行了分析。用X射线衍射测试的方法研究了热解前后锌锰电池的物质形态变化情况。对除汞率的正交统计分析表明，合适的热解条件为：热解温度690℃，热解时间100min，载气流速0.06m3/h，在这种试验条件下热解处理废锌锰电池的除汞率达到100%。同时还得到：热解时间对除汞效果影响最大，热解温度次之，载气流速的影响较小。ICP测试的结果表明：热解尾气在经过试验中设置的吸收瓶后，其中的汞被完全吸收，尾气中95%以上的汞以单质的形式存在。气相色谱分析的结果表明，热解开始后，废锌锰电池中的有机质迅速分解，其产物为C2H4、CH4和H2等。一段时间后，有机质的分解量大幅度减少，同时废电池中的石墨碳和高价金属氧化物发生氧化还原反应，生成CO气体。对废锌锰电池原料以及热解残渣的X射线衍射分析表明，当热解温度为350℃时，X射线衍射图谱上2θ值为35°附近的区域有新峰出现，但不明显，说明有结晶体形成但量不大。500℃时上述峰明显增强，这是由于ZnO和FeO形成了结晶体，同时在2θ值为41°附近有新峰出现，这是高价锰氧化物与石墨碳发生氧化还原反应生成了MnO并形成了结晶体。650℃时，2θ值在41°附近的峰显著增强，且热解过程中形成的峰稳定下来，基本上不再有新的结晶体生成。热解后，高价锰氧化物的相对含量从32.2%下降到4.6%，而MnO的相对含量则从6.4%上升到38.6%。热解后的残渣中晶体物质含量大，金属元素大多以低价态存在，适合于制备有机螯合微量元素肥料。

连续流动式聚合酶链式反应生物芯片／微装置中脱氧核糖核酸样品的驱动控制技术进展

介绍国内外连续流动式聚合酶链式反应生物芯片/微装置中脱氧核糖核酸样品的驱动控制技术进展,主要包括恒流泵(注射泵驱动和蠕动泵驱动)、旋转泵驱动、磁流体动力驱动以及自然对流驱动等。并对这几种驱动方式的优缺点作简要的讨论(引用文献43篇)。

聚苯乙烯-聚丁二烯嵌段共聚物反转相行为的研究

本论文以聚苯乙烯（PS）一聚丁二烯（PB）三嵌段和二嵌段共聚物体系为研究对象，利用聚合物的软有序化，控制聚合物分子链的取向和聚集条件，系统地考察了嵌段共聚物在由溶液成膜的过程中动力学效应和墒效应对其相结构和相转变行为的影响。并探讨了不同相结构和其力学性能之间的构效关系。设计了聚苯乙烯（PS）一聚丁二烯（PB）（PS≈30wt％）／非选择性溶剂体系，通过改变溶剂的挥发速率，控制了嵌段共聚物薄膜相结构形成的动力学过程。在快速挥发的条件下，在嵌段共聚物中观察到了特殊的反转相结构，即共聚物中含量多的组分（PB）形成了分散相，而当溶剂挥发很慢的条件下，得到的是热力学较稳定的正常相的结构。对不同分子量的一系列嵌段共聚物的研究表明，反转相的形成和分子量相关，与聚合物的链段数目无关，只有在低于临界分子量 （Mw=70-100 KDa）的嵌段共聚物中，成膜过程的动力学过程才影响嵌段共聚物薄膜的最终相态，即形成反转相。这种依赖于分子量的相转变行为，揭示了分子链运动速度与环境变化速率的匹配对嵌段共聚物薄膜有序相结构形成的重要作用，即动力学效应对聚合物软有序化的重要作用。利用冷冻干燥的方法，进一步研究了嵌段共聚物在极慢的溶剂挥发下，由溶液膜变成固体膜的过程中，随着溶液浓度的增加，不同聚合物分子链在溶液中自组织形成有序结构的过程。结果表明反转相是由稀溶液向亚浓溶液转变的过程中形成的。通过选取具有代表性的不同亲和性的溶剂：苯和环己烷及其混合溶剂，研究了溶剂对不同链段亲和性的差异对反转相形成的影响。由聚合物一溶剂相互作用参数判断，苯是体系的良溶剂，环己烷是体系的。溶剂，而苯对PS链段有较好的亲和性，与之相反环己烷对PB链段有较好的亲和性，通过对聚苯乙烯（PS）一聚丁二烯印B）二嵌段共聚物在苯和环己烷极其混合溶剂中的相转变行为的研究发现，随着溶剂对含量少的PS链段亲和性的降低，反转相不再出现。这是由于苯与PS．链段、环己烷与PB链段有更好的亲和性，嵌段共聚物在稀溶液中，在耗尽吸引的（depletion attraction）作用下，与溶剂亲和性弱的链段，在溶液中优先发生聚集，而有序聚集后导致的混合熵的损失会被更多的因有序聚集后小分子自由体积增加引起的平移嫡的增量所补偿，因此导致了嫡驱动的软有序化。最后，通过原子力显微镜纳米压印法，分别对反转相和正常相结构的纳米力学性能进行了对比研究，讨论了不同相结构间模量的差异，结果表明软段（PB）形成分散相结构时薄膜的模量总是小于硬段（PS）形成分散相结构时薄膜的模量，这主要是由嵌段共聚物不同组分的相对含量及形成的相的结构决定的。