Single muscle fiber analysis of myoclonus epilepsy with ragged-red fibers

We examined two muscle biopsy specimens from a proband and her mother with myoclonus epilepsy with ragged-red fibers (MERRF), both obtained at an interval of about 10 years, using histochemistry, in situ hybridization, and single-fiber polymerase chain reaction. Total (wild-type and mutant) mitochondrial DNAs (mtDNAs) were greatly increased in ragged-red fibers (RRF) over non-RRF in all muscle specimens analyzed. The proportion of mutant mtDNA was also significantly higher in RRF than in non-RRF. By comparing the first and second muscle biopsied specimens in each patient, we found that while the proportion of RRF, cytochrome coxidase deficient fibers, and mutant DNA in muscle changed over a 10-year period, the proportion of wild-type and mutant mtDNAs in RRF and in non-RRF was similar between the two specimens. These results suggest that the ratio of wild-type to mutant mtDNAs in RRF and non-RRF in MERRF is at a steady state level in each muscle fiber, without replicative advantage of mutant mtDNA.     

Bidirectional optical subassembly with prealigned silicon microlens and laser diode

We have succeeded in developing a low-cost bidirectional optical subassembly chip using a silicon microlens for fiber-to-the-home application. The main optical elements of the bidirectional function were automatically aligned and integrated on a silicon optical bench. The cost of subassembly was markedly lowered both by reducing the part number and simplifying the assembly process. The prototype bidirectional optical component was successfully fabricated on the basis of the proposed chip. A receiver minimum sensitivity of -28.5 dBm was experimentally demonstrated even at 75 /spl deg/C.     

Microstructures and Pyroelectric Properties of Multicomposition 0.9PbZrO3·xPbTiO3·(0.1−x)Pb(Zn1/3Nb2/3)O3 Ceramics

The microstructures and pyroelectric properties of multicomposition 0.9PbZrO₃· x PbTiO₃·(0.1− x )Pb(Zn_1/3Nb_2/3)O₃ (PZ–PT–PZN) ceramics were investigated. The PZ–PT–PZN ceramics with nearly theoretical density were prepared by spark plasma sintering at low temperature (800°C) for a very short time (10 min) from two original compositions with x = 0.025 and x = 0.050. The heat treatment was successfully used to control the diffusion between the different compositions in such ceramics. For ceramics heat-treated at 900°C, two pyroelectric peaks corresponding to the original compositions were observed. When the heat-treatment temperature was increased to 1200°C, these two pyroelectric peaks combined into one sharp pyroelectric peak, which corresponds to average composition. When the spark-plasma-sintered ceramics were heat-treated at 950°C, a high and stable pyroelectric coefficient (>100 nC·cm⁻²·K⁻¹) over a wide temperature range (23°–47°C) was obtained. It was found that the pyroelectric properties strongly depended on the microstructures.     

Fabrication of dense material having homogeneous GdAlO3–Al2O3 eutectic-like microstructure with off-eutectic composition by consolidation of the amorphous

Off-eutectic microstructures generally have both coarse crystals of rich component and ordinary eutectic microstructures. This paper shows a new method to form a dense bulk material having homogeneous eutectic-like microstructure with off-eutectic compositions. Mixture of Gd₂O₃ and Al₂O₃ powders with the off-eutectic composition was melted and quenched rapidly to form the amorphous phase. The amorphous film was pulverized. The dense bulk material could be fabricated by the consolidation of the amorphous powder using spark plasma sintering method. Field emission scanning electron microscope (FE-SEM) observation of the material showed homogeneous fine eutectic-like microstructure without coarse crystals. This is the first case that such material was successfully prepared.     

Effect of treatment conditions and titanium source on the hydrothermal synthesis of bismuth titanate particles

Hydrothermal synthesis of bismuth titanate particles was performed using various titanium sources. Uniform particles of titanium hydroxide, hydrous titania, and anatase were prepared respectively as starting materials. They were treated hydrothermally with bismuth nitrates in NaOH aqueous solution. The obtained crystal phases depended strongly upon the phase of the titanium source. Plate-like bismuth titanate particles were obtained at high-treatment temperatures when hydrous titania was used as the starting material. Spherical particles with a spherulite-like structure were obtained at low temperatures and for long treatments.     

Formation of Y3Al5O12–Al2O3 eutectic microstructure with off-eutectic composition

Homogeneous-eutectic microstructure of Y₃Al₅O₁₂–Al₂O₃ system without coarse primary crystals was formed at an off-eutectic composition. This method utilizes a low migration rate in an amorphous phase. A mixture of Y₂O₃ and Al₂O₃ having the off-eutectic composition was melted and quenched rapidly to form an amorphous phase. A heat-treatment of the amorphous phase at 1000 °C and 1300 °C for 30 min formed Y₃Al₅O₁₂ and Al₂O₃ phases. SEM observation of this material, which was formed from the amorphous phase at 1300 °C for 30 min, showed homogeneous eutectic-like microstructure. The formation of the primary crystals (coarse Al₂O₃), which are always observed in the off-eutectic compositions by ordinary method, was completely suppressed.     

Web access monitoring mechanism via Android WebView for threat analysis

Many Android apps employ WebView, a component that enables the display of web content in the apps without redirecting users to web browser apps. However, WebView might also be used for cyberattacks. Moreover, to the best of our knowledge, although some countermeasures based on access control have been reported for attacks exploiting WebView, no mechanism for monitoring web access via WebView has been proposed and no analysis results focusing on web access via WebView are available. In consideration of this limitation, we propose a web access monitoring mechanism for Android WebView to analyze web access via WebView and clarify attacks exploiting WebView. In this paper, we present the design and implementation of this mechanism by modifying Chromium WebView without any modifications to the Android framework or Linux kernel. The evaluation results of the performance achieved on introducing the proposed mechanism are also presented here. Moreover, the result of threat analysis of displaying a fake virus alert while browsing websites on Android is discussed to demonstrate the effectiveness of the proposed mechanism.

     

Synthesis and evaluation of Zr0.5Ti0.5B2 solid solution

Boride ceramics are useful materials because of their high strengths, hardness and melting points, which allow them to be used as high-temperature structural materials. In this study, sintered bodies of a solid solution of ZrB₂-TiB₂ system were prepared using hot pressing (HP) and spark plasma sintering (SPS). The sintering behavior was evaluated, and the effect of pulverization on sinterability and reactivity was examined using a Nanomizer. The combination of SPS processing at 2200 °C and pulverization yielded a nearly single-phase Zr_0.5Ti_0.5B₂ solid solution having a relative density of 95%.