Bioactive Gel Coatings Derived from Vinyltrimethoxysilane

An ethanol (EtOH) solution of polymerized vinyltrimethoxysilane (VTMS), about 20-mers, was mixed with an aqueous solution of calcium acetate (Ca(OAc)2) and refluxed in N2 for 1 h to give sols of a typical composition VTMS : H2O : EtOH : Ca(OAc)2 = 1 : 9 : 8 : 0.05 (mol). Homogeneous films could be produced, by dip-coating, on Nylon6® and soda-lime glass, but not on polypropylene or polytetrafluoroethylene. The gel films did not deposit apatite within 14 days of soaking in a simulated body fluid whereas films abraded with emery paper as well as bulk gels deposited apatite on the surfaces within 7 days, indicating the present gel was suitable for bioactive coatings on Nylon6®     

Recent advances in VLSI layout

The current status of VLSI layout and directions for future research are addressed, with emphasis on the authors' own work. Necessary terminology and definitions and, whenever possible, a precise formulation of the problems are provided. Placement and floorplanning for both the sea-of-gates and building-block designs are examined. The former emphasizes the connectivity specification, whereas the latter must also consider module shape and size. Global routing based on a method of successive cuts on a chip is discussed. This is a hierarchical top-down approach that is useful for both of the above designs. A two-dimensional detailed routing problem and the rip-up and rerouting problem are also discussed. The field of computational geometry and its application to layout-in particular, to gridless routing and compaction-are reviewed, and layout engines are considered     

Reflection multiple beam wedge plate shear interferometry for lens testing

It is shown that a multiple beam wedge plate shear interferometry can be used to represent the lateral aberration curve of a lens more accurately. For larger shear, some new artifacts appear in the interferogram which have been explained by considering contributions of higher order terms in the Taylor’s series expansion of the path Lunction.     

Ultrahigh heat transfer enhancement using nano-porous layer

Heat transfer enhancement is one of the key issues of saving energies and compact designs for mechanical and chemical devices and plants. We discover an ultrahigh convective heat transfer performance compared to the well-known heat transfer correlations caused by a nano-particle porous surface: the maximum increase of heat transfer coefficient was around 180%. This nano-particle porous layer can be formed on the substrate surface by an etching with some acids or alkalis including around 100 nm size nano-particles made from copper oxide, carbon nano-tube and aluminium oxide. Moreover, we have done some experiments using a co-current flow heat exchanger consisting of hot and cold water-channels and obtained an ultrahigh heat transfer performance: over 200% increase compared to the conventional correlation. On the other hand, in order to theoretically investigate effects of nano-particle porous layer structures on the surface energy transfer, the energy transfer from fluid to the heat transfer surface is calculated by a classical molecular dynamics method. Energy transfer to the surface from the fluid strongly depends on the surface structures in nanometre scale that affect the static structure and dynamic behaviours of fluid molecules in the vicinity of the surface.     

On catenate network formation by end-linking reactions

Catenate network formation by end-linking reactions of linear chains with bifunctional regents is studied theoretically and by computer simulations. It is found that the reaction cannot reach its stationary limit, and catenate networks are never formed by this method. An alternative method that will lead to catenate networks nearly in the topological equilibrium state is proposed. It is pointed out that catenate networks are an ideal system for studying the role of entanglement in rubber elasticity. © 1993 John Wiley & Sons, Inc.     

Multiple-subcarrier modulation in optical wireless communications

This article overviews multiple-subcarrier modulation techniques in optical wireless communications. The basic principles and characteristics of MSM techniques in optical wireless communications are presented. MSM optical wireless systems are explained where some block codes that convert information bits to be transmitted to the symbol amplitudes of subcarriers are used to increase the minimum value of the MS electrical waveform. MSM optical communications systems using subcarrier signal point sequences (SSPS) that can improve the power efficiency of MSM systems are also explained. The performance of MSM optical communications systems is presented in the intensity modulation with direct detection (IM/DD) channel without dispersion and in atmospheric optical communications where the effects of scintillation exist.     

Japan's superconducting Maglev train

We have developed a Maglev train under the guidance of the Japanese Ministry of Transport. The Maglev train is an advanced train that can run more than 500 km/h with a linear synchronous motor (LSM) that has both a superconducting magnet on board and an armature coil in the ground. The Maglev train was tested on the Yamanashi Maglev test line. Tests began in 1997, which exercised various functions of performance. The main results of the tests are reported in this article     

Elementary processes of DNA surface hybridization resolved by single-molecule kinetics: implication for macroscopic device performance

Direct monitoring of single-molecule reactions has recently become a promising means of mechanistic investigation. However, the resolution of reaction pathways from single-molecule experiments remains elusive, primarily because of interference from extraneous processes such as bulk diffusion. Herein, we report a single-molecule kinetic investigation of DNA hybridization on a metal surface, as an example of a bimolecular association reaction. The tip of the scanning tunneling microscope (STM) was functionalized with single-stranded DNA (ssDNA), and hybridization with its complementary strand on an Au(111) surface was detected by the increase in the electrical conductance associated with the electron transport through the resulting DNA duplex. Kinetic analyses of the conductance changes successfully resolved the elementary processes, which involve not only the ssDNA strands and their duplex but also partially hybridized intermediate strands, and we found an increase in the hybridization efficiency with increasing the concentration of DNA in contrast to the knowledge obtained previously by conventional ensemble measurements. The rate constants derived from our single-molecule studies provide a rational explanation of these findings, such as the suppression of DNA melting on surfaces with higher DNA coverage. The present methodology, which relies on intermolecular conductance measurements, can be extended to a range of single-molecule reactions and to the exploration of novel chemical syntheses.

Hybridization of a single DNA molecule on a surface was investigated by electrical conductance measurements. The hybridization efficiency increases with increasing the DNA concentration, in contrast to preceding studies with ensemble studies.