Phospholipid polymer hydrogel formed by the photodimerization of cinnamoyl groups in the polymer side chain

We synthesized new polymers with both photocrosslinkability and biocompatibility by a random copolymerization of 4‐(4‐methoxycinnamoyl)phenyl methacrylate and 2‐methacryloyloxyethyl phosphorylcholine. These polymers were used as prepolymers to make a hydrogel by photoirradiation. Gelation began with 5 s of photoirradiation and reached an equilibrium state after 360 s of photoirradiation. The absorption maximum at 347 nm, attributed to the cinnamoyl group, disappeared with the photoirradiation time. That is, dimerization between cinnamoyl groups in the polymer proceeded and formed a hydrogel. The equilibrium water concentration of the hydrogels was more than 90%. Moreover, we succeeded in making a microshape hydrogel on glass by photoirradiation through a photomask. The window shape of the photomask was transferred to the hydrogel that was formed. We concluded that these photocrosslinkable polymers could be useful in preparing microfluidic devices for separating or immobilizing biomolecules and cells. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 44–50, 2007     

Effect of fluorine impurity on the oxidation of silicon oxynitride ceramics doped with gadolinium oxide

Impurities in raw Si₃N₄ powders remain in intergranular glassy phases in Si₃N₄ and Si₂N₂O ceramics and degrade their high-temperature properties. Fluorine is one of the typical impurities in the raw powders. The oxidation rate of Si₂N₂O ceramics doped with Gd₂O₃ greatly varied with a difference in impurity contents (especially F) of the raw Si₃N₄ powders used. When a high concentration of impurity existed in the intergranular glassy phase, the rate of oxidation was controlled by O^2– diffusion through the glassy phase in the partly oxidized scale and unoxidized body; outward diffusion of Gd³⁺ occurred concurrently. On the other hand, when the impurity contents in the intergranular glassy phase was very low, the diffusion rate of ions (Gd³⁺, O^2–, etc.) in the glassy phase became very low (substantially zero in the oxidation at 1300°C). Only cristobalite (SiO₂) was formed on the surface. The rate of oxidation was controlled by O₂ diffusion through the cristobalite layer, and was very low.     

Intensely irradiated steel components: Plastic and fracture properties, and a new concept of structural design criteria for assuring the structural integrity

In order to develop a systematic and reasonable concept assuring the structural integrity of components under intense neutron irradiation, two basic tensile properties, true stress-true strain (TS-TS) curves and fracture strain, were investigated on an austenitic stainless steel and martensitic steel. Application of Swift equation is confirmed to a large plastic strain range of TS-TS curves. Fracture strain ?_f data were well correlated as ?_f + ?₀ = const. where ?₀ is the pre-strain representing the irradiation hardening.Based on those formulations and available experimental information, several critical issues to be dealt with in developing the concept were identified possible reduction in ductility, significant change in mechanical properties, remarkable cyclic softening and other unique cyclic properties observed during a high-cycle fatigue testing, and the redundancy of the plastic collapse concept to bending. Existing structural codes are all based on the assumption that there will be no significant changes in mechanical properties during operation, and of high ductility. Therefore, a new concept for assuring structural integrity is required for application not only to components with high ductility but also components with reduced ductility. First, potential failure modes were identified, and a new and systematic concept was proposed for preventing these modes of failure, introducing a new concept of categorizing the loadings by stability of deformation process to fracture (as type F and M loadings). Based on the basic concept, a detailed concept of how to protect against ductile fracture was given, and loading type-dependent limiting parameters were set.Finally, application of the detailed concept was presented, especially on determination of loading type (in numerical approach, the formulation of TS-TS curves and fracture strain derived above are needed), and on how to determine the limiting parameters as allowable limits. Experiments were done to identify the loading type of a tensile loading acting on a structure with a discontinuity. Tensile loadings acting on an intensely neutron-irradiated flat plate with a hole in the center cause plastic tensile instability and necking at the minimum ligament section but do not initiate any surface crack at the initiation of necking.     

Evaluation of longitudinal chromatic dispersion

The relationship between changes in the refractive index along a fiber and chromatic dispersion is investigated theoretically. The variance of the chromatic dispersion along a fiber is approximately proportional to that of longitudinal structural fiber parameters. To control the dispersion to within ±1 ps/km/nm, theoretical results indicate that the longitudinal deviations of the core radius and relative index difference must be less than 0.04 μm and 0.014%, respectively, for W-type dispersion-flattened fiber. Measurements of the standard deviation of the change in the longitudinal parameter for W-type dispersion-flattened fiber fabricated by the vapour axial deposition VAD method show that chromatic dispersion deviation is mainly caused by longitudinal core radius deviation. The effective standard deviation of the core radius is estimated to be within 0.03 μm     

Mode field diameter measurement conditions for fibers by transmitted field pattern methods

The transmitted near- and far-field pattern methods, measuring the mode field diameter of the fundamental LP01mode in a single-mode fiber are studied. On the basis of measurement error evaluation, the optimum measurement conditions for typical single-mode fibers are determined. Actual measured values for nearly ideal step-index fibers are in good agreement with the theoretical predictions (within 0.2 μm with a standard deviation of 0.05 μm). The mode field diameter measurement by the transmitted field pattern methods is useful for the study of the structural optimization of the single-mode fibers.     

Simple approximations for chromatic dispersion in single- mode fibers with various index profiles

Simple approximate formulas of chromatic dispersion and zero-chromatic dispersion wavelength are empirically derived for single-mode fibers with various index profiles having the deformations such as a central dip, hump, and/or tailing at a core cladding interface. These profiles are typical which are commonly obtained in current single-mode fibers. The approximation is based on the exact solution of vector-wave equation. These accuracies are better than 0.3 and 0.03 percent for the chromatic dispersion and zero-chromatic dispersion wavelength, respectively. With the aid of the simple approximations, the properties of chromaric dispersion and zero-chromatic dispersion wavelength for practical single-mode fibers are discussed. The relation between the chromatic dispersion and basic fiber parameters of single-mode fibers, effective cutoff wavelength of the LP11mode, and the spot-size of the LP01mode, are clarified.     

Rapid sensing of trace ionic substances with the novel porous monolith type ion exchanger

Biological and chemical sensor with a rapid response in microlevel test is required for health and environmental monitor. A novel sensing due to porous ion exchanger with three-dimensional acceptor has been first attempted to develop a high-performance sensor. This porous monolith type ion exchanger has an open-cellular monolith structure with 5–50-μm diameter pores. The trace amount of inorganic ions dissolved in aqueous solutions can be quantitatively determined with the impedance given by the monolith, which attracts and adsorbs the ions rapidly. We have succeeded in detecting ions with a concentration as low as 10⁻⁷ mol. The porous ion exchanger has a potentiality as a high-performance device for biological and chemical sensing. POLYM. ENG. SCI., 47:1666–1670, 2007. © 2007 Society of Plastics Engineers     

Niobium–aluminum oxynitride prepared by ammonolysis of oxide precursor obtained through the citrate route

Oxynitrides in the (Nb_1−xAl_x)(O,N) quaternary system were prepared by ammonolysis of oxide precursor obtained through the citrate route. The products at 1000 °C were a mixture of Nb(N,O) and NbN_0.95 at the niobium end (x = 0) and amorphous Al(O,N) at the aluminum end (x = 1). A new cubic compound (A) appeared mixed with Nb(N,O) in the compositional range 0.1 ≤ x ≤ 0.4. Its almost pure product was obtained at x = 0.5. The X-ray diffraction pattern was rock salt type (Nb_0.56Al_0.44)(O_0.38N_0.37□₀₂₅) in F_m−3m with a = 0.43481(1) nm. The product showed superconductivity with T_c = 15 K. Its crystallinity was much improved and its superconducting volume fraction increased to 32% after its thermal annealing at 1100 °C in evacuated sealed tube. A second cubic compound (B), rock salt type Nb[(O,N)_0.85□_0.15] with a = 0.434 nm, was observed mixed with amorphous Al(O,N) in the as-prepared products of the range 0.6 ≤ x ≤ 0.9.     

Modular high temperature reactor (Modular HTR) contributing the global environment protection

Rapid increasing of the energy demand and the economic growth of the developing countries are threatening to lead to unstable supply of the fossil resources and the aggravation of the global environment. Modular High Temperature Reactor (Modular HTR) is one of the most effective solutions of such problem. The GT-MHR (Gas-Turbine Modular Helium Reactor) is a typical plant of the Modular HTR, which is a high efficiency nuclear power generating plant, combined the Modular HTR having passive safety characteristics with the direct cycle helium gas turbine. It has sufficient potential to contribute the global environment protection with keeping the growing speed of the developing countries.

Fuji Electric joined the international GT-MHR project in January 1997 and has helped to finance it. Fuji Electric, in the behalf of the other participants of this project, introduces the outline of this project and main system of the GT-MHR plant in this paper.