Relative permittivity and conductivity of water‐treed region in XLPE estimated by an equivalent circuit

By dividing a water‐treed XLPE sheet sample of 1 mm thickness into a nondegraded region and a water‐treed one, relative permittivity and AC conductivity σ_AC2 of the water‐treed region have been estimated using an equivalent circuit. The variation of and σ_AC2 with the length r of the water‐treed region has been discussed based on the Sillars model. It was concluded that the volume fraction of water in the water‐treed layer is in the range from 0.5% to 1.5% for the most‐degraded XLPE sheet, which depends on the ratio of axes of spheroids to which water‐filled voids and channels are compared. It was also concluded that the AC conductivity of water in the water‐treed region ranges from 3 × 10^?3 S/m to 2 × 10^?2 S/m. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 148(3): 7–14, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10332     

Improvement of diamond X-ray mask membrane: Optical transmittance, surface roughness and irradiation durability

A viable method for the improvement of the polycrystalline diamond X-ray mask membrane is proposed. The use of an ionized cluster beam yields the smoothest surface. Sol-gel planarization film coating with indium tin oxide is the most effective method for obtaining high optical transmittance without sacrificing high synchrotron irradiation durability.     

In vivo absorption of porous apatite- and wollastonite-containing glass-ceramic

The behavior of porous apatite- and wollastonite-containing glass-ceramic (AW) in the bone marrow cavity was investigated. Cylinders of porous AW (4 mm in diameter and 20 mm long, mean porosity of 70% and mean pore diameter of 200 microm) were implanted into the bone marrow cavity of rabbit femurs, and analyzed by chronological radiograms and by scanning electron microscopy one, three, six, and 12 months later. The pores of porous AW are interconnected and homogeneously distributed, and its compressive strength is nearly equal to that of human cancellous bone. Bone formed in the pores at the center of the material by one month and bonded to the material directly. The volume of newly formed bone in the material pores reached a peak at three months, and decreased gradually after six months. The trabecular structures of AW were gradually remodeled by newly formed bone, while AW-bone bonding was maintained during bone remodeling and material absorption. AW was absorbed continuously, and at six and 12 months the residual material corresponded to about 64 and 30% of the starting material, respectively. Porous AW may therefore be useful as an absorbable bone substitute.     

Magnetic properties of the solid solutions,YxDy1−xC2

Magnetic properties of the solid solutions, Y_xDy_1?xC₂, were investigated. All of them exhibit?d antiferromagnetic behavior. The values of the Neel temperature and the paramagnetic Curie temperature were plotted linearly against the de Gennes factor, (g?1)²J(J+1). This result was discussed in terms of the Ruderman-Kittel- Kasuya-Yosida theory.     

循环荷载下砂质混合土孔隙水压力特性研究

通过对各种细颗粒含量的土实施从小到大应变水平的动力循环荷载试验,采用累积损失能量的观点,分别考察了土的细颗粒成分含量、围压、加载频率、加载形式及荷载的不规则性对孔压的影响,提出了孔隙水压力和累积损失能量的归一化方法,建立了砂质混合土的孔隙水压力上升模型,并探讨了模型参数和土的细颗粒成分含量的关系。     

Radiation-induced seeded copolymerization of tetrafluoroethylene with propylene. II. Kinetic analysis

The radiation-induced seeded copolymerization of tetrafluoroethylene with propylene was kinetically analyzed by assuming that growing radical in polymer particle is deactivated by degradative chain transfer to propylene and/or by recombination with newly entered radical which grows for a while before recombination. Apparent rate constant of initiation is 2.6 × 10^?9 mole/liter rad independent of the monomer composition in polymer particles. Apparent rate constant of propagation lies in the range of 10⁵ hr^?1 increasing with tetrafluoroethylene fraction. Change in apparent rate constant of chain transfer with propylene fraction suggests that first-order termination by radical occlusion or radical escape to aqueous phase may occur simultaneously with the degradative chain transfer. Average number of radical in a particle is found to increase with dose rate and levelled off at the value of 0.9. The higher value above 0.5 is explained by Trommsdorff effect. The dose rate exponent of average number of radical changes from 1 to 0 with increasing dose rate. This change is consistent with the dose rate effect on the polymerization rate under the constant number of polymer particles.     

Total sputtering yields of solids under MeV-energy Si ion bombardment

Total sputtering yields have been measured for SiO₂ and Cu targets bombarded with Si ions at an incident energy between 500 keV and 5.0 MeV using a quartz crystal microbalance technique. In order to measure total yields accurately, we have developed a beam modulation technique to avoid the effect of thermal drift. In the MeV energy range, an ion penetrates through thin SiO₂ and Cu targets and is implanted into a quartz crystal. Therefore, the thickness of these layers deposited on quartz crystals was carefully controlled to avoid damage of quartz crystal by incident ions. As a result, total sputtering yields of SiO₂ increased with incident Si ion energy, while those of the Cu target decreased. The total yields of the SiO₂ target were represented well by a power low of the electronic stopping power.     

1.6 Gbit/s optical receiver at 1.3 ?m with SAW timing retrieval circuit

The performance of a 1.6 Gbit/s optical receiver employing a s.a.w. filter as a timing tank is reported. The error-rate characteristics in a p.c.m. transmission system using a 1.3 ?m In-GaAsP laser and single-mode fibres were studied. The average received optical power at a 10?9 error rate was ?28 dBm. In a 15 km transmission experiment, the receiving level was degraded by 2 dB owing to fibre dispersion. Timing phase margin of 75 degrees after 12 km transmission was confined with the self-timed receiver.     

Electron Spin Resonance of High-Spin Co2+ in Alkali Borate and Alkali Germanate Glasses

Electron spin resonance spectra of high-spin Co²⁺ doped in alkali borate and alkali germanate glasses have been measured at 4.2 K. For comparison, the corresponding spectrum in a 33K₂O·67SiO₂ glass has also been measured. On the basis of the spectral line shape, the observed spectra, together with those in the literature, seem to be classified into four spectral types that represent Co²⁺ ions in octahedral coordination, a mixture of some types of coordination, tetrahedral coordination with nearly axial symmetry, and distorted tetrahedral coordination.