Electric‐Field‐Induced Alignment of Block Copolymer/Nanoparticle Blends

External electric fields readily align birefringent block‐copolymer mesophases. In this study the effect of gold nanoparticles on the electric‐field‐induced alignment of a lamellae‐forming polystyrene‐block‐poly(2‐vinylpyridine) copolymer is assessed. Nanoparticles are homogeneously dispersed in the styrenic phase and promote the quantitative alignment of lamellar domains by substantially lowering the critical field strength above which alignment proceeds. The results suggest that the electric‐field‐assisted alignment of nanostructured block copolymer/nanoparticle composites may offer a simple way to greatly mitigate structural and orientational defects of such films under benign experimental conditions.     

Flexible High‐Conductivity Carbon‐Nanotube Interconnects Made by Rolling and Printing

Applications of carbon nanotubes (CNTs) in flexible and complementary metal‐oxide‐semiconductor (CMOS)‐based electronic and energy devices are impeded due to typically low CNT areal densities, growth temperatures that are incompatible with device substrates, and challenges in large‐area alignment and interconnection. A scalable method for continuous fabrication and transfer printing of dense horizontally aligned CNT (HA‐CNT) ribbon interconnects is presented. The process combines vertically aligned CNT (VA‐CNT) growth by thermal chemical vapor deposition, a novel mechanical rolling process to transform the VA‐CNTs to HA‐CNTs, and adhesion‐controlled transfer printing without needing a carrier film. The rolling force determines the HA‐CNT packing fraction and the HA‐CNTs are processed by conventional lithography. An electrical resistivity of 2 mΩ · cm is measured for ribbons having 800‐nm thickness, while the resistivity of copper is 100 times lower, a value that exceeds most CNT assemblies made to date, and significant improvements can be made in CNT structural quality. This rolling and printing process could be scaled to full wafer areas and more complex architectures such as continuous CNT sheets and multidirectional patterns could be achieved by straightforward design of the CNT growth process and/or multiple rolling and printing sequences.     

A flow‐aligning algorithm for convection‐dominated problems

This paper proposes and studies an algorithm for aligning a triangulation with a given convection field. Approximate solutions of convection‐dominated problems on flow‐aligned meshes typically have sharper internal layers, less over and undershooting and higher accuracy. The algorithm we present can be imported easily into any 2D finite element solver, does not change the number of meshpoints, and can improve solution quality quite dramatically. This improvement in solution quality on the flow‐aligned triangulation is illustrated for both the usual Galerkin method and the streamline‐diffusion method. Copyright © 1999 John Wiley & Sons, Ltd.     

Finger vein recognition using minutia‐based alignment and local binary pattern‐based feature extraction

With recent increases in security requirements, biometrics such as fingerprints, faces, and irises have been widely used in many recognition applications including door access control, personal authentication for computers, Internet banking, automatic teller machines, and border‐crossing controls. Finger vein recognition uses the unique patterns of finger veins to identify individuals at a high level of accuracy. This article proposes a new finger vein recognition method using minutia‐based alignment and local binary pattern (LBP)‐based feature extraction. Our study makes three novelties compared to previous works. First, we use minutia points such as bifurcation and ending points of the finger vein region for image alignment. Second, instead of using the whole finger vein region, we use several extracted minutia points and a simple affine transform for alignment, which can be performed at fast computational speed. Third, after aligning the finger vein image based on minutia points, we extract a unique finger vein code using a LBP, which reduces false rejection error and thus the equal error rate (EER) significantly. Our resulting EER was 0.081% with a total processing time of 118.6 ms. © 2009 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 19, 179–186, 2009     

Cover Picture: Bistable Nematic Liquid Crystals with Self‐Assembled Fibers (Adv. Mater. 6/2005)

The cover shows a recording process using nematic liquid crystal alignment. On p. 692, Kato and co‐workers report that reversibly bistable states have been achieved for nematic liquid crystals incorporating a small amount of self‐assembled fibers. Homeotropic monodomains and non‐aligned multidomains can be fixed and switched by thermal treatment in electric fields. The technique is applied to the formation of rewritable light scattering patterns, as shown on the cover.