A structural study on the stabilization and enhancement of mesophase pitch fibre

The components of coal tar-derived mesophase pitch fibre and its blend with polyvinyl chloride (PVC) pitch were studied for chemical changes after the stabilization. Microanalyses, solubility and solid ¹³C NMR measurements were performed. The temperature was found to be very influential on the progress of the stabilization. At a temperature of 230° C, PVC pitch enchanced the oxygen uptake of both fusible pyridine soluble (PS) and non-fusible pyridine insoluble (PI) fractions in the pure mesophase pitch, so shortening the time required for complete stabilization and raising more rapidly the softening point of the PS fraction. More oxygen-containing functional groups, such as phenolic, ether, carboxylic and carbonyl groups, were formed in both fractions. It is noted that any increase in the aromatic ring size of the PI fraction is rather limited at this temperature. In contrast, stabilization of PVC pitch at a higher temperature of 300° C, accelerated the increase in PI without accelerating oxygen uptake of both fractions. Hence, the softening point of the remaining PS was unchanged or even lowered. An increase of aromatic ring size of the PI component by stabilization was marked at the higher temperature. Suggested stabilization schemes and the role of added PVC pitch in accelerating stabilization are discussed for each of these temperatures taking account of the above results.     

Circular multilayer zone plate for high-energy x-ray nano-imaging

A circular multilayer zone plate (MZP) was fabricated and its focusing performance was evaluated using 20-keV x-rays. MoSi(2) and Si layers were alternately deposited by DC magnetron sputtering on a wire core; all the interfaces satisfied the Fresnel zone condition. The measured line spread function was converted to a point spread function by tomographic reconstruction. The results suggest that the MZP has the potential to realize the diffraction-limited resolving power, which is calculated to be 35 nm using the diffraction integral. Furthermore, scanning transmission microscopy using the MZP could resolve a 50-nm line-and-space pattern.     

Control of molecular orientations in mesophase pitch-based carbon fibre by blending PVC pitch

Coal tar-derived mesophase pitch and its blends with PVC pitch in 5 or 10 wt% were spun at temperatures from 340 to 390° C by applying pressurized nitrogen. The parent mesophase pitch and the blended pitch showed an excellent spinnability at temperatures from 360 to 380° C and from 350 to 380° C, respectively, to give a thin pitch fibre of 10m diameter. The transverse texture of the fibres from the parent mesophase pitch showed the radial orientation regardless of a higher spinning temperature of 390° C. In contrast, those from the blended pitches showed random orientation even at the lower spinning temperature of 350° C. The amounts of the blend extruded by spinning at each temperature under 0.2 kg cm^–2 G^–1 were always larger than those of the mesophase pitch. It is clarified in the present study that blending PVC pitch can realize stable spinning at lower temperatures, where the molecular orientation in the transverse section of the resultant carbon fibre was controlled through decreasing the viscosity of the whole mesophase pitch.     

Preparation of PbTiO3 thin films by laser ablation

Abstract

PbTiO₃ thin films have been deposited on Si or Pt substrates by laser ablation method using ArF excimer or YAG laser. Species evaporated in the vacuum have been studied by mass analysis, and the measured Pb and Ti are not oxidized. Spacial distributions of the deposition rates on the substrate have been studied as a parameter of laser fluence. The excimer laser gives better films than the YAG. Perovskite films have been obtained at substrate temperature ～ 400 °C and appropriate ambient O₂ gas pressure.     

Characteristics of lead-plastic laminate tape for water-impervious XLPE cable

To take full advantage of combined effects of metal and plastic materials, a composite tape combining lead foil which lacks mechanical strength with plastic film which imparts strength has been developed. This composite tape is designed to serve the purpose of a water-impervious layer in an XLPE cable. Evaluation of its properties such as corrosion resistance, fatigue, expansion and shrinkage was made. The results of tests indicate that the combination of lead foil with plastic film is more effective in several ways than either alone. As one of its applications, the lead laminate tape was used as a water-impervious layer in an XLPE cable. This composite material may be used not only in XLPE cable applications but also in many other various fields of industry.     

Long‐period observation of neutral current at an extra‐high‐voltage transformer in Chubu region

We have observed and recorded the neutral current of a 500‐kV transformer at a substation in the Chubu region since 2008 in order to detect electromagnetic anomalies associated with earthquakes. In this study, we could not ?nd any particular anomalous change of the neutral current before and after earthquakes (e.g., for the Suruga Bay Earthquake of August 11, 2009). However, from the results of a quantitative analysis between geomagnetic ?eld data and neutral current data, we would be able to investigate the underground electric conductivities near the substations. It would be possible to monitor changes of subsurface electromagnetic structure before and after earthquakes. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 183(1): 32–38, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22297     

A convenient method to estimate the rate of heat evolution in fermentation

The estimation of heat of fermentation is discussed with reference to experimental data obtained in glucose-, ammonia- and oxygen-limited chemostat cultures of a specific bacterium and also to previous data published by other workers. Whatever the microbial or cultural conditions might be, the heat of fermentation can be easily estimated from TOD (total oxygen demand) measurement, accompanied by the concept of available electrons. If aerobic pathways are dominant in a particular fermentation, the specific rate of heat evolution, Q_H, can be calculated approximately from Q_H = Q_o2 (?δH_o^7ast;), where ? 7delta;H_o^* = 106 kcal/mol O₂, using only Q_o2 values without the need for either TOD or calorimetric determination.     

Orthogonal aperture multiplexing for multilayered waveguide holographic read-only memories

A multilayered waveguide holographic read-only memory is a promising candidate for the next generation of optical data storage systems. We improved the data density of the memory by using a multiplexing method with a set of orthogonal optical masks. We multiplexed as many as nine images into one waveguide hologram, and all the observed images had negligible cross talk. This made it possible to achieve a ninefold increase in data density. We provide experimental results for both metallic and liquid-crystal masks.     

Contribution of protein-surface ion pairs of a hyperthermophilic protein on thermal and thermodynamic stability

Hyperthermophilic proteins possess many ion pairs on their surface. To reveal the role of the ion pairs, O6-methylguanine-DNA methyltransferase from Thermococcus kodakaraensis KOD1 (Tk-MGMT) was studied as a model protein. The maximum free-energy changes of the protein in 0.1 and 0.5 M NaCl at pH 7.0 were 61.7 kJ mol(-1) at 31.5 degrees C and 77.4 kJ mol(-1) at 39.7 degrees C, respectively. On the other hand, mid points of the thermal unfolding temperatures in 0.1 and 0.5 M NaCl at pH 7.0 were 94.8 degrees C and 90.1 degrees C, respectively. The results suggest that the protein-surface ion pairs contribute to thermal stability (Tm), rather than thermodynamic stability (DeltaG).