Photosensitive polycarbonates based on reaction development patterning (RDP)

Summary Films of commercially available poly(bisphenol A carbonate) (BPA-PC) and poly[bisphenol A carbonate-co-4,4'-(3,3,5-trimethylcyclohexylidene)diphenol carbonate] (BPA-TMC-PC) containing photosensitive agent (diazonaphthoquinone (DNQ) compound) were prepared by spin-coating onto copper foil. The obtained films showed positive-tone behavior by UV irradiation and following development with ethanolamine/N-methylpyrrolidone (NMP)/H₂O mixture (1/1/1 by weight). The scanning electron microscope (SEM) photographs of the resulting images exhibited fine patterns (∼10 μm line/space resolution) with 15–16 μm film thickness. The pattern forming mechanism is based on the Reaction Development Patterning (RDP), in which the carboxylic acid resulting from photo-rearrangement of DNQ in the film attracts ethanolamine in the developer and the amine reacts with carbonate in the main chain to induce degradation of the polymer. RDP, where the main pattern forming reaction occurs during the development, is proved to be efficient for polycarbonates as well as polyimide. Received: 11 July 2001/Accepted: 1 August 2001     

Mimicking Nanometer Atomic Processes on a Micrometer Scale via Electrophoretic Deposition

The process of submonolayer formation during the electrophoretic deposition (EPD) of colloidal films of micrometer-sized (diameter ∼ 0.5 μm) silica particles on a silicon wafer has been observed as a function of deposition time. The process of nucleation and growth of the silica monolayer is compared with that of atomic film growth (10000 times smaller scale) via molecular-beam epitaxy (MBE), and for the first time, a striking similarity between the two growth processes is observed. Likewise in the atomic growth process via MBE, the entire nucleation, growth, and aggregation process during EPD of silica particles can be broadly classified into two regions. At low surface coverage when silica particles are deposited outside of clusters, diffuse randomly, and stick to a cluster on touching them, the mechanism of growth in this region follows diffusion-limited aggregation (DLA) and the fractal dimension of the two-dimensional clusters is found to be close to 1.65. Later on, as the clusters grow in size, deposition of particles inside the clusters become important and clusters become more and more compact, resulting in a dense, close-packed, and homogeneous monolayer. This region is termed a consolidation region, and a change in fractal dimension from 1.65 toward 2 with increasing surface coverage has been observed.     

Study of flow fractionation characteristics of magnetic chromatography utilizing high-temperature superconducting bulk magnet

We present numerical simulation of separating magnetic particles with different magnetic susceptibilities by magnetic chromatography using a high-temperature superconducting bulk magnet. The transient transport is numerically simulated for two kinds of particles having different magnetic susceptibilities. The time evolutions were calculated for the particle concentration in the narrow channel of the spiral arrangement placed in the magnetic field. The field is produced by the highly magnetized high-temperature superconducting bulk magnet. The numerical results show the flow velocity difference of the particle transport corresponding to the difference in the magnetic susceptibility, as well as the possible separation of paramagnetic particles of 20 nm diameter.     

Module production, centrality, and M&A in the keiretsu of Mazda

Relationship analysis is one of the most interesting issues in interorganizational management. The relationships between an auto maker and parts suppliers in the keiretsu of Japan, as one special case, have recently been greatly changed due to the diffusion of module production. Parts suppliers are required to develop their capacity for research and development (R&D) and parts integration to cope with the new situation. Mergers and acquisitions (M&A) are carried out by these parts makers. In order to measure the transactional relationship between centrality and module production, we reviewed the literature of module production and interorganizational research from the viewpoint of networks, and measured the eigenvector, one of the centrality indices, of the transaction network in the keiretsu of Mazda using the two fiscal years of 1995 and 2005. We analyzed the changes in interorganizational relationships between the years 1995 and 2005, and identified the relationship between centrality and the module system. Furthermore, we discussed the implications of our new findings about the transaction network in Mazda.     

TWO CRACK GROWTHS IN A FUNCTIONALLY GRADED PLATE UNDER THERMAL SHOCK

This article examines the problem of two thermal cracks under a transient temperature field in a ceramic/metal functionally graded plate. When the functionally graded plate is subjected to thermal shock, multiple cracks often occur on the ceramic surface. It is shown that the crack paths are influenced by interaction between multiple cracks and a compositional profile of the functionally graded plate. Transient thermal stresses are treated as a linear quasi-static thermoelastic problem for a plane strain state. The crack paths of two cracks are obtained using the finite element method with mode I and mode II stress intensity factors.     

Reaction properties of catalytic antibodies encapsulated in organo substituted SiO2 sol-gel materials

Catalytic antibodies (38C2 and 84G3) were encapsulated in hybrid organic-inorganic sol-gel powder prepared from tetraethoxysilane (TEOS) and organoalkoxysilanes, then used to catalyze enantioselective aldol reactions. Sol-gel immobilization enhanced antibody stability with respect to the effect of temperature and organic solvent concentration.     

Data analysis on solar irradiance and performance characteristics of solar modules with a test facility of various tilted angles and directions

We examined and evaluated the output characteristics and the deterioration lowering factors of modules installed under various conditions (module directions and tilted angles) based on the data collected at the multi-position test facility, which was produced and installed in order to conduct evaluation using design parameters (correction coefficient). This report introduces example data and the results of our evaluation.     

Static concentrator photovoltaic module with prism array

To obtain cost-effective photovoltaic modules, we have developed static prism-array concentrator modules consisting of prism concentrators about 4 mm thick assembled unidirectionally under a 3.2-mm-thick cover glass. Calculating the optical collection efficiency for the annual solar irradiation in Tokyo, we found that the theoretical efficiency of the modules is 94.4% when the geometrical concentration ratio is 1.88 and that it is 89.1% when that ratio is 2.66, respectively. Fabricating prism-array-concentrator modules with a geometrical concentration ratio of 2.66, we obtained a maximum optical collection efficiency of 82% with a flat reflector and 81.7% with a V-grooved reflector.     

Three-dimensional discrete-velocity BGK model for the incompressible Navier–Stokes equations

The lattice Boltzmann method (LBM) has been widely used for the simulations of the incompressible Navier–Stokes (NS) equations. The finite difference Boltzmann method (FDBM) in which the discrete-velocity Boltzmann equation is solved instead of the lattice Boltzmann equation has also been applied as an alternative method for simulating the incompressible flows. The particle velocities of the FDBM can be selected independently from the lattice configuration. In this paper, taking account of this advantage, we present the discrete velocity Boltzmann equation that has a minimum set of the particle velocities with the lattice Bharnagar–Gross–Krook (BGK) model for the three-dimensional incompressible NS equations. To recover incompressible NS equations, tensors of the particle velocities have to be isotropic up to the fifth rank. Thus, we propose to apply the icosahedral vectors that have 13 degrees of freedom to the particle velocity distributions. Validity of the proposed model (D3Q13BGK) is confirmed by numerical simulations of the shear-wave decay problem and the Taylor–Green vortex problem. With respect to numerical accuracy, computational efficiency and numerical stability, we compare the proposed model with the conventional lattice BGK models (D3Q15, D3Q19 and D3Q27) and the multiple-relaxation-time (MRT) model (D3Q13MRT) that has the same degrees of freedom as our proposal. The comparisons show that the compressibility error of the proposed model is approximately double that of the conventional lattice BGK models, but the computational efficiency of the proposed model is superior to that of the others. The linear stability of the proposed model is also superior to that of the lattice BGK models. However, in non-linear simulations, the proposed model tends to be less stable than the others.