A simple test method,NAL-II,to evaluate the strength and elastic modulus of polymer matrix composite laminates

This study proposes and assesses a simple test method (NAL-II) to evaluate compressive properties of carbon fiber-reinforced polymer matrix composite laminates (CFRP). Compressive tests based on ASTM D6641 and NAL-II methods were conducted for direct comparison using three kinds of quasi-isotropic composite laminates (T800H/3633, T800S/3900-2B, and IM600/133). Stress–strain curves including the compressive modulus obtained using the NAL-II method showed good agreement with those obtained using the ASTM D6641. The NAL-II method gave slightly higher (approximately 10%) compressive strengths than the ASTM D6641 method, probably because of suppression of bending (buckling) before failure. The experimentally obtained results suggest that the NAL-II method can be useful for international standard testing of the non-hole compressive strength of CFRP laminates.     

Effects of amines on the formation of β-ferric oxide hydroxide

Colloidal particles of -ferric oxide hydroxide (-FeOOH) were prepared by ageing an FeCl₃ solution at 100°C in the presence of various amines with different numbers of nitrogen atoms. The particle and crystallite sizes of the formed -FeOOH decreased with increasing concentration of amines, but the particles produced contained no amine. The influence of triethanolamine on the growth of -FeOOH particles was more marked than those of ethylenediamine, diethylenetriamine and triaminotriethylamine. The adsorption isotherms of nitrogen and water on the formed particles of different size were measured and surface fractal analysis was performed.     

Synthesis and polymerization of nucleic acid base substituted L-lysine

Summary Poly-l-lysines containing nucleic acid bases, that is, adenine, thymine, uracil and theophylline were synthesized. The nucleic acid base substituted l-lysine derivatives were prepared from ,N-Cbz-l-lysine and the p-nitrophenyl esters of the carboxyethyl derivatives of the nucleic acid bases. The polymers were obtained from these l-lysine derivatives by the NCA method.     

Effect of the compatibility on toughness of injection‐molded polypropylene blended with EPR and SEBS

The effect of the compatibility between a dispersed phase and a matrix polymer and the annealing on improvement in the toughness of injection‐molded isotactic polypropylene (i‐PP) blended with elastomers was studied. Two grades of ethylene‐propylene copolymer (EPR(A) and EPR(B)) and styrene‐ethylene‐butadiene‐styrene tri‐block copolymer (SEBS) were used as elastomer. EPR(B), which has lower strength than EPR(A), was able to improve the toughness of i‐PP more effectively than EPR(A). However, SEBS, which has higher strength than EPR(B), was more effective than EPR(B). This result contradicts the toughening mechanism of relaxing the strain constraint due to void formation. Two reasons are probable. First, the volume fraction of the dispersed phase of the i‐PP blended with EPR(B), hereinafter referred to as EPR(B)/i‐PP, is much lower than that of the i‐PP blended with SEBS (SEBS/i‐PP) because of the high compatibility between EPR and i‐PP. Second, it is possible that the dissolved i‐PP in EPR increases the strength of the dispersed phase. In this case, the void formation from the dispersed phase is restricted. Therefore, the efficiency of toughness improvement by relaxing the strain constraint is decreased. The annealing improves the phase separation. As a result, the strength of the dispersed phase is decreased, and therefore the toughness is improved. The effect of the annealing of EPR(B)/i‐PP is higher than that of SEBS/i‐PP because of the high compatibility between EPR and i‐PP. POLYM. ENG. SCI., 46:29–38, 2006. © 2005 Society of Plastics Engineers     

Instability of Quantized Vortices Attached to Oscillating Boundaries in Superfluid 4He

The motion of quantized vortices is studied using a vibrating wire in superfluid ⁴He. A vortex filtering method provides a superfluid practically free of remanent vortices in which the vibration of a wire cannot generate turbulence. Vortex lines are produced by cooling through the superfluid transition and remain forming bridges between a wire and a surrounding wall. Bridged remanent vortices increase the resonance frequency of a vibrating wire: the rate of an increase due to the remanent vortices is constant in a laminar flow regime and steeply increases in a turbulent flow regime with increasing wire velocity. These results suggest that oscillation of the bridged vortices provides a linear contribution to the wire vibration in the laminar flow regime, until instability occurs in the oscillation of the vortices, causing turbulence.      

Development of a shrouded wind turbine with a flanged diffuser

We have developed a wind turbine system that consists of a diffuser shroud with a broad-ring flange at the exit periphery and a wind turbine inside it. The flanged-diffuser shroud plays a role of a device for collecting and accelerating the approaching wind. Emphasis is placed on positioning the flange at the exit of a diffuser shroud. Namely, the flange generates a low-pressure region in the exit neighborhood of the diffuser by vortex formation and draws more mass flow to the wind turbine inside the diffuser shroud. To obtain a higher power output of the shrouded wind turbine, we have examined the optimal form of the flanged diffuser, such as the diffuser open angle, flange height, hub ratio, centerbody length, inlet shroud shape and so on. As a result, a shrouded wind turbine equipped with a flanged diffuser has been developed, and demonstrated power augmentation for a given turbine diameter and wind speed by a factor of about 4-5 compared to a standard (bare) wind turbine. In a field experiment using a prototype wind turbine with a flanged diffuser shroud, the output performance was as expected and equalled that of the wind tunnel experiment.     

Synthesis and luminescent properties of low oxygen contained Eu^2＋-doped Ca-α-SiAION phosphor from calcium cyanamide reduction

A new convenient calcium cyanamide （CaCN2） reduction route was developed to synthesize the Eu^2＋ activated Ca-α-SiAION phosphors containing low oxygen content. The luminescence properties of the obtained products were investigated for white LEDs application. The critical Eu^2＋ concentration in various hosts and its effect on the photoluminescence properties were studied. The optimized sample （10at.% Eu^2＋ vs. Ca^2＋） could be efficiently excited by the current GaN/InGaN blue LED chips and provided emission intensity competitive with that of YAG：Ce^3＋ （P46-Y3） standard, revealing that this phosphor was a potential candidate for phosphor-converted white LEDs.     

Fabrication of a simultaneous red-green-blue reflector using single-pitched cholesteric liquid crystals

A cholesteric liquid crystal (CLC) is a self-assembled photonic crystal formed by rodlike molecules, including chiral molecules, that arrange themselves in a helical fashion. The CLC has a single photonic bandgap and an associated one-colour reflection band for circularly polarized light with the same handedness as the CLC helix (selective reflection). These optical characteristics, particularly the circular polarization of the reflected light, are attractive for applications in reflective colour displays without using a backlight, for use as polarizers or colour filters and for mirrorless lasing. Recently, we showed by numerical simulation that simultaneous multicolour reflection is possible by introducing fibonaccian phase defects. Here, we design and fabricate a CLC system consisting of thin isotropic films and of polymeric CLC films, and demonstrate experimentally simultaneous red, green and blue reflections (multiple photonic bandgaps) using the single-pitched polymeric CLC films. The experimental reflection spectra are well simulated by calculations. The presented system can extend applications of CLCs to a wide-band region and could give rise to new photonic devices, in which white or multicolour light is manipulated.     

Development of a radon trap device using a corona discharge

Radon is one of the noble gases, which are chemically inert and do not make any reactants under normal conditions. In this experiment we demonstrated an enigmatic reaction between radon and fluorine when a corona discharge is used as a promoter. Distinctive changes in radon concentrations were caused by the discharge and a trap efficiency of >99.5% was estimated. The mass balance between the trapped and the released radon was found to be reasonable. This indicates the existence of chemical reactions with radon. This trap phenomenon has application as a technique for reducing radon concentration in radon-contaminated air. It is possible that this technique will be applicable to other noble gases.     

Wave-optical evaluation of interference fringes and wavefront phase in a hard-x-ray beam totally reflected by mirror optics

The intensity flatness and wavefront shape in a coherent hard-x-ray beam totally reflected by flat mirrors that have surface bumps modeled by Gaussian functions were investigated by use of a wave-optical simulation code. Simulated results revealed the necessity for peak-to-valley height accuracy of better than 1 nm at a lateral resolution near 0.1 mm to remove high-contrast interference fringes and appreciable wavefront phase errors. Three mirrors that had different surface qualities were tested at the 1 km-long beam line at the SPring-8/Japan Synchrotron Radiation Research Institute. Interference fringes faded when the surface figure was corrected below the subnanometer level to a spatial resolution close to 0.1 mm, as indicated by the simulated results.