Super‐ductile PBT alloy with excellent heat resistance

A super‐ductile PBT alloy with excellent heat resistance was successfully fabricated by reactive blending of poly(butylene terephthalate) (PBT) with poly(ethylene‐co‐glycidyl methacrylate) together with linear low density polyethylene (LLDPE) and hydrogenated styrene‐butadiene‐styrene block copolymer (SEBS). It possesses a unique tensile stress–strain curve with no yielding point and large elongation at break, moreover, the alloy did not show serious deterioration of the mechanical properties by high temperature annealing at 150°C for 96 h. The structure‐properties relationship is discussed on the basis of transmission electron microscopy, differential scanning calorimetry, dynamic mechanical analysis, and wide‐angle X‐ray diffraction analysis. The outstanding ductile nature seems to come from the negative pressure effect of LLDPE (or LLDPE/SEBS) particles that dilates the PBT ligament matrix to enhance the local segment motions. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers.     

Vasorelaxant effect of olprinone, an inhibitor of phosphodiesterase 3, on mesenteric small artery and vein of rabbits

An augmented synthesis of tetrahydroisoquinolines, such as salsolinol (SAL) or an increased N-methylation of these compounds has been addressed by various investigators as putative pathophysiologic mechanisms in Parkinson's disease (PD). Aim of this study was (1) to investigate putative relations between plasma levels of dopamine and R- and S-enantiomers of SAL and (2) whether these metabolic precursors of the neurotoxic N-methylated-SAL (NMSAL) are elevated in untreated "de-novo" Parkinsonian patients compared to age- and sex-matched healthy controls. Plasma levels of R- and S-SAL and dopamine did not significantly (R-SAL: p=0.61, S-SAL: p=0.51, dopamine: p=0.84) differ in both groups. Parkinsonian patients' R-SAL plasma levels were inversely related to intensity (p=0.03, r =-0.42) and duration of PD (p=0.03, r=-0.43) in contrast to S-SAL and dopamine. Dopamine levels were not associated to R-SAL (p=0.88, r2=0.0008) and S-SAL (p=0.088, r2=0.12) neither in Parkinsonian patients nor in controls. We conclude, that an upregulation of N-methylation of tetrahydroisoquinolines takes place in PD by enzymes such as neutral N-methyltransferase specific for R-SAL. The activity of this enzyme has been found elevated in parkinsonian lymphocytes. This increased N-methylation by the N-methyltransferase specific for R-SAL leads to the known augmented levels of neurotoxic R-NMSAL in Parkinsonian patients compared to controls in the cenral nervous system especially in the beginning of PD.     

Secular degradation of crystalline photovoltaic modules

The performance of crystalline photovoltaic (PV) modules has been measured once a year in field exposure. Their maximum power output (P_max) decreases 4.8% for single-crystalline PV modules and 2.0% for the poly-crystalline case in comparison with their initial P_max at ex-work after five years' field exposure.This paper describes the secular degradation of crystalline PV modules.     

Dielectric characteristics of turn-to-turn insulation models of gas-insulated transformer under very fast transient voltages

This paper deals with the partial discharge inception voltage (PDIV) and breakdown voltage (BDV) characteristics of turn-to-turn insulation models for SF₆ gas-insulated transformers in the presence of steep-front short-pulse voltages, whose waveforms are 35/65 ns and 50/370 ns. It was determined that PDIV at nanosecond pulses were 1.05 to 1.15 times higher than those at standard impulse voltages and that the BDV at nanosecond pulses were about 1.4 times higher than those at standard impulse voltages. The ratio of impulse PDIV to ac PDIV is 1.40 to 1.48 for standard impulse voltages and 1.32 to 1.37 for switching impulses. © 1998 Scripta Technica, Inc. Electr Eng Jpn, 121(3): 36–43, 1997     

Detailed analyses of key phenomena in core disruptive accidents of sodium-cooled fast reactors by the COMPASS code

A five-year research project has been initiated in 2005 to develop a code based on the MPS (Moving Particle Semi-implicit) method for detailed analysis of key phenomena in core disruptive accidents (CDAs) of sodium-cooled fast reactors (SFRs). The code is named COMPASS (Computer Code with Moving Particle Semi-implicit for Reactor Safety Analysis). The key phenomena include (1) fuel pin failure and disruption, (2) molten pool boiling, (3) melt freezing and blockage formation, (4) duct wall failure, (5) low-energy disruptive core motion, (6) debris-bed coolability, and (7) metal–fuel pin failure. Validation study of COMPASS is progressing for these key phenomena. In this paper, recent COMPASS results of detailed analyses for the several key phenomena are summarized. Simulations of GEYSER and THEFIS experiments were performed for dispersion and freezing behaviors of molten materials in narrow flow channels. In particular, the latter experiment using melt–solid mixture is also related to fundamental behavior of low energy disruptive core. CABRI-TPA2 experiment was simulated for boiling behavior of molten core pool. Expected mechanism of heat transfer between molten fuel and steel mixture was reproduced by the simulation. Analyses of structural dynamics using elastoplastic mechanics and fracture criteria were performed for SCARABEE BE+3 and CABRI E7 experiments. These two analyses are especially focused on thermal and mechanical failure of steel duct wall and fuel pin, respectively. The present results demonstrate COMPASS will be useful to understand and clarify the key phenomena of CDAs in SFRs in details.     

Secondary electron emission from a thin carbon foil induced by equi-velocity protons and electrons of 0.5-3.5 MeV/u

The statistical distributions of the number of simultaneously forward-emitted secondary electrons (SEs) from a thin carbon foil have been measured with H⁰ and H⁺ projectiles of 0.5-3.5 MeV in coincidence with the foil-transmitted protons, irrespective of projectile incident charge state. From these results, the probabilities of the simultaneous emission of n electrons and the SE yields by loss electrons have been evaluated. At energies of 2.5-3.5 MeV, the obtained emission probabilities and the SE yields induced by loss electrons are larger than the corresponding ones by protons of the same velocity. Furthermore, the material parameter is found to be almost constant and is slightly larger than that for the protons. On the other hand, the forward SE yields by loss electrons is decreasing to zero with decreasing the incident energy. This behavior is consistent with the range-energy relation of electrons in carbon.     

Theoretical evaluation for thermodynamic stability of constituents of Mm-based hydrogen storage alloy in 6 M KOH solution at relatively high temperatures

Potential-pOH diagrams of some components constituting AB₅-type Mm-based (Mm: misch metal) hydrogen storage alloy were drawn at various temperatures to predict the deterioration behaviors of the alloy in an alkaline solution at relatively high temperatures. Based on these diagrams, the thermodynamic stability of each constituent of the alloy in 6 M KOH solution at various temperatures was evaluated. As A components, in the charge–discharge potential range, Nd(OH)₃ was extremely stable at temperatures lower than 70°C, while Ce(OH)₃ was oxidized to CeO₂ at the end of discharge above −0.496 V versus NHE at 70°C. On the other hand, as B components, Mn, Al and Co dissolved easily as HMnO₂⁻, AlO₂⁻ and HCoO₂⁻ ions in 6 M KOH solution and their solubility increased with increasing temperature. However, HCoO₂⁻ ion was reduced to metallic Co at the charge process. All oxidation reactions, particularly the dissolution of Mn and Al, proceeded at relatively high temperatures.     

Inhibitory effect of alginic acids on hyaluronidase and on histamine release from mast cells

The effects of various types of alginic acid consisting of L-guluronic acids (G) and D-mannuronic acids (M) on hyaluronidase and mast cell degranulation were examined. Alginic acid with an M/G ratio of 1.0 exhibited the strongest inhibition of both activities, the higher molecular weight alginic acids of 150 to 370 kDa being preferable in both cases. Esterification of the carboxyl residue enhanced the latter activity.     

Development of the basic structure for an exoskeleton cyborg system

The internal human skeleton is referred to as an endoskeleton, while the cuticles of lobsters and crabs are referred to as exoskeletons. Much research has been conducted in attempts to combine endoskeletons and exoskeletons. However, there are very few instances of research being undertaken to create a cyborg. The human endoskeleton consists of kinematic pairs that are joined together with a maximum of three degrees of kinematic freedom. These are a turning pair on a lateral-bending axis, a turning pair on a longitudinal-bending axis, and a turning pair on the central axis of a skeleton. If the strength of the muscles on a human skeleton decline, or if component parts of a human skeleton are lost, then a module-type exoskeleton designed with a maximum of three degrees of kinematic freedom would be able to contain an entire body so that it could assist the functions of the arms, hands, legs, and other body parts to complement the declining or lost physical functions (kinematic or biological). Based on this concept, it is possible to develop an exoskeleton cyborg system that behaves in much the same way that a human does in daily life. This work was presented in part at the 7th International Symposium on Artificial Life and Robotics, Oita, Japan, January 16–18, 2002     

Dynamically-Stable Motion Planning for Humanoid Robots

We present an approach to path planning for humanoid robots that computes dynamically-stable, collision-free trajectories from full-body posture goals. Given a geometric model of the environment and a statically-stable desired posture, we search the configuration space of the robot for a collision-free path that simultaneously satisfies dynamic balance constraints. We adapt existing randomized path planning techniques by imposing balance constraints on incremental search motions in order to maintain the overall dynamic stability of the final path. A dynamics filtering function that constrains the ZMP (zero moment point) trajectory is used as a post-processing step to transform statically-stable, collision-free paths into dynamically-stable, collision-free trajectories for the entire body. Although we have focused our experiments on biped robots with a humanoid shape, the method generally applies to any robot subject to balance constraints (legged or not). The algorithm is presented along with computed examples using both simulated and real humanoid robots.