Reliability of AllnAs/lnGaAs/lnP HEMT with WSi ohmic contacts

We have investigated the degradation mechanism of Al_0.48In_0.52As/In_0.53Ga_0.47As/ InP high electron mobility transistors (HEMTs) using WSi ohmic electrodes. Cross-sectional transmission electron microscopy (TEM) observation and en-ergy dispersive x-ray (EDX) analysis reveal impurities diffusion of gate electrode (titanium: Ti) and fluorine (F) in the AlInAs layer after a high temperature (T_a = 170°C operating life test for 500 h. The decrease of drain current (I_ds) during life test shows linear dependence on square root of aging time. It suggests that the degradation is controlled by a diffusion mechanism. Hence, the estimated degradation mechanism of this device is related with decrease of carrier concentration in the epitaxial layer by these diffused impurities. On the other hand, TEM and EDX show no degradation of WSi/InGaAs interface after aging. Therefore, the WSi electrode for this type of HEMT demonstrates excellent high stability under the accelerated operating life test.     

S-methylation in Parkinson's disease

We report thiolmethyltransferase (TMT) activity in RBC membrane preparations from patients with Parkinson's disease (PD), normal controls, and patients with symptomatic parkinsonism. Unlike previous reports, our report found no significant decrease in TMT activity in PD patients compared with normal controls. Low S-methylation capacity does not appear to be a risk factor for PD in Japanese patients.     

Distribution of platinum in human gynecologic tissues and pelvic lymph nodes after administration of cisplatin

OBJECTIVE: The purpose of this study was to develop a diverting colostomy technique for use in dogs. STUDY DESIGN: Clinical case series. ANIMALS: Five client-owned dogs presented for diseases requiring diverting colostomy during treatment. METHODS: Diverting colostomy was performed in five dogs. A ventral approach was used in the first dog and the colon was exteriorized adjacent to the linea alba. The technique used in the next four dogs involved creation of a left flank rod-supported loop colostomy in which the colon was exteriorized through a muscle-separating flank approach to the abdomen. RESULTS: Peritoneal leakage of fecal material resulted in the perioperative death of the first dog. The flank colostomies were maintained for times ranging form 3.5 weeks to 7 months. No major complications were observed, but skin excoriation occurred occasionally around the stoma sites in all dogs. CONCLUSION: Diverting colostomy is a technique that is suitable for use in treatment of dogs with obstruction or leakage involving the distal colon or rectum.     

A 5-μm-wide 18-cm-long low-loss YBa2Cu3O7-δ coplanar line for future multichip moduletechnology

Narrow and low-loss YBa₂Cu₃O_7-δ (YBCO) coplanar lines, which can be used in multichip module technology for future high-density and high-speed digital circuits, have been developed. Etch-back planarization and a patterning process combining Ar-ion milling and wet-etching enabled us to form an 18-cm-long 5-μm-wide YBCO coplanar line without electrical shorts, even for the narrow spacing of 2.5 μm. The surface resistance of this line was kept at a level comparable to that of 10- or 25-μm-wide YBCO coplanar lines and also comparable to that of unpatterned films. This indicates successful fabrication of the 5-μm-wide YBCO coplanar line without notable loss increase resulting from process damage. The 5-μm-wide line showed a low-transmission loss of 0.49 dB at 10 GHz and 55 K. This level of loss is similar to that in Cu coaxial cables. No significant increase in transmission loss was observed up to an input power level of 16 mW at 10 GHz and 55 K. This input power is comparable to the power-handling capability required for transmitting high-speed digital signals through the lines with characteristic impedance of 50 Ω. These results show that the narrow 5-μm-wide YBCO coplanar line has great potential for high-density and high-speed digital circuits     

Radiation tolerance of the cochlear nerve at the gamma-knife in rabbits

Since the first treatment of acoustic neurinoma using the gamma-knife by Leksell, a series of cases have been reported with good control rates. However, the most frequent complication is delayed hearing loss which occurs in more than 50% of patients. The purpose of this study was to define a safe dose by analyzing the radiosurgical dose-response relationship and histological effects on the normal cochlear nerve in rabbit. The rabbits had computed tomography (CT)-guided stereotactic radiosurgery on their cochlear nerves in the internal auditory canal with a 4 mm collimator focusing of a gamma-unit. Maximum doses of 10, 20, 30, 40, 60, 80, 100, 200 and 500 Gy were administered. After the radiosurgery, auditory brain stem responses (ABR) and the behavior of the rabbits were evaluated periodically. At the conclusion, histological investigations were performed. No physiological or histological findings were observed from doses of 30 Gy or below during the 12 month period after the radiosurgery. A dose of 100 Gy caused a severe ABR threshold elevation, vestibular dysfunction and facial palsy. Necrosis and demyelination of nerves were observed pathologically. In this study, we determined that the safe dose to the normal cochlear nerve during radiosurgery was under 40 Gy in rabbits, and complications seemed to vary due to individual differences in radiation tolerance.     

Low resistivity transparent conducting Al-doped ZnO films prepared by pulsed laser deposition

A series of AZO films were grown on glass substrates by a method of pulsed laser deposition using a split target divided into AZO (Al₂O₃: 1 wt.%) and AZO (Al₂O₃: 2 wt.%). The film deposition took place at a substrate temperature of 230 °C within a magnetic field applied perpendicularly to the plume. To suppress the droplet generation caused by the intense laser energy, the laser energy density was reduced to 0.75 J/cm² (15 mJ). For an approximately 280-nm thick-AZO film grown at a target-to-substrate distance of 25 mm, we obtained the lowest resistivity of 8.54×10⁻⁵ Ω·cm and an average transmittance of more than 88% in the visible range. In the cross-sectional TEM observation and XRD spectra, the regularity in the crystal growth was generated immediately from the interface between the substrate and the film.     

Activity tests of various catalysts for hydrocracking of coal by means of high pressure differential thermal analysis

The activities of fourteen kinds of catalysts for the hydrocracking of Taiheiyo coal were examined by a high pressure differential thermal analytical method. Exothermic peaks appeared at low temperatures (420–430°C) when MoO₃TiO₂, NiY zeolite and CoY zeolite were used as catalysts, indicating that these catalysts are highly active compared with other catalysts including MoO₃CoOAl₂O₃. The qualitative analysis of gas and liquid products revealed that MoO₃TiO₂ and CoY are good catalysts for the liquefaction reaction. The hydrogenation ability of the catalyst is concluded to be more important than its acidic property.     

Quantitative level population mechanism in gas discharges for pulsed argon-ion lasers

The time-resolved intensities of hundreds of spontaneous-emission lines relating to four4plaser levels belonging to a doublet and the time dependences of electron temperature and density were measured under 10-μs pulse excitation at high currents. The pumping and decay rates were calculated only for the4pdoublet as a function of time. The influence of radiation trapping on the4sdoublet is discussed. It is shown that the ratio of the cascade pumping rate to the total pumping rate of the4pdoublet increases during the last half of a 10-μs pulse. Moreover, the relative important of the cascade transitions in the formation processes of the4p^{2}P_{3/2}laser level increases some what with time.     

An Approach to Multi-Service Subscriber Loop System Using Packetized Voice/Data Terminals

A new subscriber communication system and its design philosophy are described. In addition to telephone communication, the system is simultaneously able to offer data communication, still picture communication, etc. The system is composed of a packetized voice/data terminal, a multi-service switching equipment and the digital subscriber loop connecting between them. The system utilizes the existing subscriber line efficiently and is entirely suitable for coming telephone and data public digital network. 64 kbit/s PCM coded voice conversation and 48 kbit/s data communication were achieved simultaneously over 96 kbit/s digital subscriber line which was spanned up to 2 km.