Anisotropy of styrene–butadiene rubber

Anisotropy of styrene–butadiene rubber (SBR) was investigated. The anisotropy of the copolymer varies linearly with the styrene content and the ultimate value coincides with that of polystyrene at elevated temperature. From these facts, the transverse configuration of the pendant phenyl group is estimated irrespective of the styrene content of SBR.     

Monitoring biofilm development in a microfluidic device using modified confocal reflection microscopy

The feasibility of a method to monitor biofilm development non-destructively in a microfluidic device was addressed. Here, we report that biofilm growth could be non-destructively monitored by an image analysis technique based on modification of confocal reflection microscopy.     

Evaluation of drug toxicity with hepatocytes cultured in a micro-space cell culture system

A micro-space cell culture system was recently developed in which cells such as hepatocytes can be cultured and formed into a multicellular three-dimensional (3D) architecture. In this study, we assessed the performance of HepG2 cells cultured in this micro-space cell culture system in a drug toxicity test, and evaluated the effects of micro-space culture on their hepatocyte-specific functions. The micro-space cell culture facilitated the formation of 3D HepG2 cell architecture. HepG2 cells cultured in a micro-space culture plate exhibited increased albumin secretion and enhanced mRNA expression levels of cytochrome P450 (CYP) enzyme compared to those cultured in a monolayer culture. When the cells were exposed to acetaminophen, a hepatotoxic drug, the damage to the HepG2 cells grown in micro-space culture was greater than the damage to the HepG2 cells grown in monolayer culture. In addition, human primary hepatocytes grown in micro-space culture also exhibited increased albumin secretion, enhanced CYP mRNA expression levels and increased sensitivity to acetaminophen compared to those grown in monolayer culture. These results suggest that this micro-space culture method enhances the hepatocyte-specific functions of hepatocytes, including drug-metabolizing enzyme activities, making hepatocytes grown in the micro-space culture system a useful tool for evaluating drug toxicity in vitro.     

Simultaneous visualization of oxygen distribution and water blockages in an operating triple-serpentine polymer electrolyte fuel cell

Visualization inside polymer electrolyte fuel cells (PEFCs) is important for elucidating reaction distributions to improve the performance and durability of the cells. An O₂-sensitive porphyrin luminescent dye film was used to visualize oxygen partial pressures and water blockages simultaneously in triple-serpentine gas flow channels in an operating PEFC. Water droplets formed near the exit of a gas-flow channel lowered the oxygen partial pressure noticeably over the channel by blocking air flow near the entrance. Meanwhile, air was continuously supplied from the other channels through the gas diffusion layer, thus allowing power to be generated in the blocked channel. With water blockages, however, the catalyst layer under the channel became flooded by the water produced during the reaction, and the flooded state continued to exist in the catalyst and/or porous layers, even after blowing the water droplet out, so that the power generation was lowered along the channel.     

Application of energy capacitor system to wind power generation

In this paper, it is reported that energy capacitor system (ECS), which combines power electronic devices and electric double‐layer capacitor, can significantly decrease voltage and power fluctuations of grid‐connected fixed‐speed wind generator. The proper selection of wind farm output power reference is still a problem for smoothing the wind farm output power. This paper proposes exponential moving average to generate the reference output power of a grid‐connected wind farm. The objective of the control system is to follow the line power reference by absorbing or providing real power to or from the ECS. Moreover, the necessary reactive power can also be supplied to keep the wind farm terminal voltage at the desired reference level. Real wind speed data were used in the simulation analyses, which validate the effectiveness of the proposed control strategy. Simulation results clearly show that our proposed ECS can be suitable for wind power application. Copyright © 2007 John Wiley & Sons, Ltd.     

A theory of pseudo cross-link

Summary A theory of pseudo cross-link model suggests the existence of multiple links of various size composed of 116 segmental units. They possesses the heat and entropy of various magnitude giving various transition temperature, T_A for the cross-link composed of 4 segments and T_B for that of 16 segments. The glass-transition point T_g and the melting point T_m are defined by the different size of lateral multiple links. Relationships, T_m = 2 T_A and T_g = (2/3)T_m = (4/3)T_A, are derived. A wedge-type relaxation spectrum is obtained as a distribution of size of cross-links. For temperature dependence the WLF-equation is obtained.     

a study of cast alloys with partially dispersed graphite III: Characterization of high density dispersed surfaces

The characteristic features of cast alloys with partially dispersed graphite are wear resistance and toughness. The friction and wear performance, hardness and other surface characteristics of the cast alloys with a high dispersive density of 60% at the casting surfaces were studied.The reciprocating sliding wear volume of aluminium alloy AC7A containing dispersants decreases with an increase in the gravity variable G = 2π²DN²/60²g, where D (cm) is the diameter of rotation, N (rev min^?1) is the rotational speed and g (cm s^?2) is the acceleration due to gravity, but depends on the nature of the dispersants. The effect of casting temperature on the wear loss was not significant. The dispersive density at the near-surface regions which is susceptible to the magnitude of G has a direct effect on the wear loss. A dense dispersant has an adverse effect on wear resistance and lubricity. A relation between surface roughness and casting temperature is also reported.     

Profile structure of magnetic flux lines in type-II superconductor from a rectangular electron hologram

Profile magnetic configuration of a quantized flux line and flux-line lattice penetrating a type-II superconductor thin foil, niobium, was observed by electron holography and Lorentz microscopy using a 300 kV field-emission electron microscope. Each single flux line was distributed periodically as lattice structure in the mixed state just below its critical temperature of 8.5 K, while at low temperature of 5 K the flux lines were weakly bound as bundles. In order to observe the flux-line distribution over a wide area, discrete Fourier transform reconstruction in the holography was extended for a rectangular area without loss of information and data precision.     

A generative model of article citation networks of a subject from a large-scale citation database

Scientometrics - In this paper, we analyze the structure of the article citation network of a particular subject obtained from the Web of Science (WoS) database. In specific, we modify a model...