Ultra-slim laminated capillary array for high-speed DNA separation

We developed a new kind of capillary array for electrophoresis by using the numerical-control (NC) wiring technique conventionally used to produce printed-circuit boards. Laminating two polyimide sheets after laying cylindrical capillaries between them according to designed geometries, we fabricated a 16-lane laminated capillary array (LCA) 9.9 cm long, 7.2 cm wide, and 0.5 mm thick in which the effective length of all capillaries was only 10.9 cm. This compact LCA thus had separation columns as short as those in capillary array electrophoresis chips fabricated by lithography techniques. Like conventional capillary arrays, it also enabled pipetting-less direct injection of analytes from sample preparation plates. Using the LCA with LIF detection and a replaceable fluid sieving matrix, we demonstrated high-speed ssDNA fragment separations. At an electric field strength of 316 V/cm, 15 fragments ranging from 50 to 500 bases were completely separated within 5.8 min in all lanes. The lane-to-lane CV of migration time was only 0.38%, and the fragment size for which the resolution per base was 0.59 was 258 +/- 15 bases (average +/-SD).     

聚合物锂离子电池阴极热复合聚集状态对电池性能的影响

制备了多层复合的聚合物锂离子电池 ,研究热压复合温度对电池性能的影响 .热压复合温度是聚合物锂离子电池生产中的一个关键控制参数 ,阴极片在合适的热压温度下 ,电池的性能较好 ;温度偏高或偏低都对电池不利     

Lamination-based rapid prototyping of microfluidic devices using flexible thermoplastic substrates

Transposing highly sensitive DNA separation methods (such as DNA sequencing with high read length or the detection of point mutations) to microchip format without loss of resolution requires fabrication of relatively long (approx. 10 cm) microchannels along with sharp injection bands. Conventional soft lithography methods, such as mold casting or hot-embossing in a press, are not convenient for fabricating long channels. We have developed a lamination-based replication technique for rapid fabrication of sealed microfluidic devices with a 10 cm long, linear separation channel. These devices are fabricated in thin cyclo-olefin copolymer (COC) plastic substrates, thus making the device flexible and capable of assuming a range of 3-D configurations. Due to the good optical properties of COC, this new family of devices combines multiple advantages of planar microfluidics and fused-silica capillaries.     

一种用于电阻型超导限流器新型结构的第二代高温超导带材

电阻型超导故障限流器(R-SFCL) 结构简单、 限流效果好等优点, 在电力系统中具有广阔的应用前景. 超导故障限流器的发展经历了实验级、 配电级、 输电级样机研制等阶段. 随着超导限流器容量不断攀升, 由于单根材料性能的限制, 不可避免在系统中会采用大量的串并联方式. 带材的临界电流和耐瞬态冲击能力决定着一个限流器在额定电流通流下和过流冲击下的并联支路数. 带材的失超电阻决定着一个限流器在一定故障电流抑制率下的串联支路数. 通过分析目前 REBCO 超导带材的参数和典型的限流器设计参数, 发现了超导带材电流和耐过流冲击相差近3 倍的关系. 本文提出了一种宽的不锈钢封装窄的超导带结构, 目的是让不锈钢的宽度与超导带材的宽度保持在3 倍的关系, 以贴合部分限流器的需求. 经过测试, 结果显示低成本新结构的超导带材瓶颈性能保有原结构带材的91 .3% , 成本下降一半, 这对未来电阻型超导限流器成本的降低来说是一个非常好的选项.     

Laminations minimales résiduellement à 2 bouts

Résumé On décrit toutes les feuilles des laminations minimales dont un ensemble résiduel de feuilles ont 2 bouts.      

On computing the entropy of braids

We consider the problem of computing the entropy of a braid. We recall its definition and for each braid construct a sequence of real numbers whose limit is the braid’s entropy. We state one conjecture on the convergence speed and two conjectures on braids that have high entropy but are written with few letters.      

An upper bound to the free energy of n-variant polycrystalline shape memory alloys

In the last two decades, the problem of computing the elastic energy of phase transforming materials has been studied by a variety of research groups. Due to the non-quasiconvexity of the underlying multi-well landscape, different relaxation methods have been used in order to estimate the quasiconvex envelope of the energy density, for which no explicit expression is known at present.This paper combines a recently developed lamination bound for monocrystalline shape memory alloys which relies on martensitic twinned microstructures with the work of Smyshlyaev and Willis [1998a. A ‘non-local’ variational approach to the elastic energy minimization of martensitic polycrystals. Proc. R. Soc. London A 454, 1573–1613]. As a result, a lamination upper bound for n-variant polycrystalline martensitic materials is obtained.The lamination bound is then compared with Reuß- and Taylor-type estimates. While, for given volume fractions, good agreement of lamination upper and convexification lower bounds is obtained, a comparison using energy-minimizing volume fractions computed from the various bounds yields larger differences. Finally, we also investigate the influence of the polycrystal's texture. For a strong ellipsoidal texture, we observe even better agreement of upper and lower bounds than for the case of isotropic statistics.     

层压工艺对埋入光纤传输性能影响分析

针对层压工艺下,埋入挠性光电基板的光纤,其应力、位移的变化,会影响光路的耦合效率,改变光纤有效折射率,导致传输性能发生变化的问题,采用有限元分析软件,对光纤埋入不同槽型的挠性光电基板进行了力学、传热和电磁场耦合分析.分析结果表明:光纤埋入梯形槽挠性基板的应力最大,达到68.336 7MPa.埋入梯形槽的光纤位移量最大,其值为1.430 4μm.随着槽宽增加,光纤最大等效应力从52.667MPa增加至71.907 MPa;随着槽间距增加,光纤最大应力从51.589 MPa增加至53.567MPa;随着槽深增加,光纤最大应力从52.667MPa减小至47.793 8 MPa,然后增加到67.349 6MPa.随着温度和压力的增加,单模光纤在X方向的有效折射率从1.446 249 977增加至1.446 259 084;Y方向的有效折射率从1.446 326 398增加至1.446 393 041.光纤有效折射率差会随着温度的增加而增大,随着压力的增加而减小.光纤有效折射率增加,限制光的能力增加,能够有效地减小光纤弯曲损耗.本文分析结果对挠性光电基板光纤埋入结构设计和层压工艺具有一定的参考价值和指导意义.     

A time-domain high-order spectral finite element for the simulation of symmetric and anti-symmetric guided waves in laminated composite strips

A time domain spectral finite element is developed for improving the efficiency of numerical simulations of guided waves in laminated composite strips. The finite element relies on a new generalized laminate mechanics model formulated to represent symmetric and anti-symmetric Lamb waves. The laminate mechanics incorporate third-order polynomial terms for the approximation of axial and transverse displacement fields through the thickness and consider the displacements of the upper and lower surfaces as degrees of freedom. The laminate theory formulation is easily expanded to a high-order layerwise model. Based on the resultant governing equations of the laminate section, a new finite element with 8 nodal degrees of freedom is formulated; its nodes are collocated with Gauss–Lobatto–Legendre integration points in order to improve computational efficiency. Stiffness and mass matrices are assembled and the transient response is predicted using the explicit central differences time integration scheme. The transient response of Aluminum, Carbon Fiber Reinforced Polymer laminated and sandwich strips is investigated. Numerical results are validated against a semi-analytical solution. The accuracy and computational efficiency of the introduced element regarding the prediction of symmetric and anti-symmetric wave propagation is also quantified.