Fabrication technology of stable Schottky barrier gates for gallium arsenide MESFETS

An improved structure for stable GaAs Schottky gates formed by the lift-off technique is described. Schottky gates made by the lift-off process often have an interfacial layer and resulting MESFETS have unsatisfactory characteristics. To obtain a transfer characteristic unaffected by the interfacial layer, using rhodium for the contacts is effective. In the case of nickel Schottky contact with interfacial layer, MESFET transfer characteristics are improved by annealing the contact. The Ni film for the contacts consumes GaAs corresponding to its thickness during alloying. To reduce the consumption of GaAs, a thin Ni film should be used.     

Effective cutoff wavelength of the LP11mode in single-mode fiber cables

The effective cutoff wavelength of the LP11mode is investigated for nylon-coated step-index type single-mode fibers stranded in a cable. It is found from the pulse propagation experiments that the single-mode operation is effectively attained in the two-mode region up to theV-value of 3.0. It is numerically estimated that splice loss, bending loss, and absorption loss due to the OH-ion in cladding are reduced by choosing the operatingV-value as large as 3.0.     

Detection and identification of microcystins in the drinking water of Haimen City, China

The main method of classification of chronic viral hepatitis is now by cause, and the old histology-based classification is no longer considered appropriate. However, liver biopsy remains an important part of patient assessment and, in the context of clinical trials, biopsy findings are often scored in a semiquantitative manner. The concepts of grading and staging, borrowed from tumour pathology, have been introduced, representing the severity of the necroinflammatory lesion and the extent of its structural consequences respectively. The pathology of the individual forms of viral hepatitis A to G shows more similarities than differences. However, some pathological features are commonly associated with specific viruses. The combination of portal lymphoid follicles, bile duct damage, lobular activity and steatosis give chronic hepatitis C a characteristic histological profile. Very similar appearances have been noted in the limited number of biopsies so far reported from patients with known combined hepatitis C and G virus infection.     

Site-specific phosphorylation of synapsin I by mitogen-activated protein kinase and Cdk5 and its effects on physiological functions

Posttranslational modifications of synapsin I, a major phosphoprotein in synaptic terminals, were studied by mass spectrometry. In addition to a well known phosphorylation site by calmodulin-dependent protein kinase II (CaM kinase II), a hitherto unrecognized site (Ser553) was found phosphorylated in vivo. The phosphorylation site is immediately followed by a proline, suggesting that the protein is an in vivo substrate of so-called proline-directed protein kinase(s). To identify the kinase involved, three proline-directed protein kinases expressed highly in the brain, i.e. mitogen-activated protein (MAP) kinase, Cdk5-p23, and glycogen synthase kinase 3beta, were tested for the in vitro phosphorylation of synapsin I. Only MAP kinase and Cdk5-p23 phosphorylated synapsin I stoichiometrically. The phosphorylation sites were determined to be Ser551 and Ser553 with Cdk5-p23, and Ser62, Ser67, and Ser551 with MAP kinase. Upon phosphorylation with MAP kinase, synapsin I showed reduced F-actin bundling activity, while no significant effect on the interaction was observed with the protein phosphorylated with Cdk5-p23. These results raise the possibility that the so-called proline-directed protein kinases together with CaM kinase II and cAMP-dependent protein kinase play an important role in the regulation of synapsin I function.     

Mid-term results in coronary revascularization using the right gastroepiploic artery graft

We studied the mid-term results in 191 patients (including emergent operation in 27 patients) who have performed coronary artery bypass grafting (CABG) using the right gastroepiploic artery (REGA) for 74 months (mean follow up period was 37 months). We evaluated the postoperative results in terms of 1. mortality and survival rate, 2. graft angiography, 3. cardiac event free rate and 4. abdominal complications. We had operative death in 6 patients (3.1%) including 3 patients of emergent operations. Late deaths were found in 11 patients (5.9%): 2 patients were cardiac death and 9 were non-cardiac. The actual survival rates were 94.2% at one year, 90.0% at three years and 85.9% at five years. Early patency rate of the RGEA was 98.9% (n = 178). However flow competition between the RGEA and native coronary artery was seen in 42 patients (24.0%). Mid-term patency rate was 96.4% (n = 28). According to mid-term graft angiography, 1 patient improved and 5 patients got worse in comparison with early control. Cardiac event free rates were 98.2% at 1 year, 94.8% at 3 years and 92.7% at 5 years. Abdominal complications were observed in 5 patients (1 patient of bleeding from the RGEA, 1 of gastric perforation, 2 of bleeding from gastric ulcer and 1 of pyloric stenosis) at early period and in 7 patients (2 patients of incisional hernia and 5 of gastric cancer) at long-term period. Early and mid-term results of CABG using the RGEA were quite good. However, the RGEA had a tendency of flow competition against native coronary artery and a problem of gastric cancer after the operation.     

Modified silicone as new type of primary coat for optical fibre

It is confirmed that modified silicone is the most suitable for the primary coat of optical fibre. The modified silicone-coated fibre with a silicone buffer and a nylon jacket is found to have high mechanical strength and stable transmission characteristics.     

Evaluation of flow accelerated corrosion by coupled analysis of corrosion and flow dynamics. Relationship of oxide film thickness, hematite/magnetite ratio, ECP and wall thinning rate

Systematic approaches to evaluate flow accelerated corrosion (FAC) are desired before discussing application of countermeasures for FAC. First, future FAC occurrence should be evaluated to identify locations where a higher possibility of FAC occurrence exists, and then, wall thinning rate at the identified FAC occurrence zone is evaluated to obtain the preparation time for applying countermeasures.Wall thinning rates were calculated with two coupled models:

1.

static electrochemical analysis and

2.

dynamic oxide layer growth analysis.

The anodic current density and the electrochemical corrosion potential (ECP) were calculated with the static electrochemistry model based on an Evans diagram. The ferrous ion release rate, determined by the anodic current density, was applied as input for the dynamic double oxide layer model. Some of the dissolved ferrous ion was removed to the bulk water and others precipitated on the surface as magnetite particles.The thickness of oxide layer was calculated with the dynamic oxide layer growth model and then its value was used as input in the electrochemistry model. It was confirmed that the calculated results (corrosion rate and ECP) based on the coupled models were in good agreement with the measured ones.Higher ECP was essential for preventing FAC rate. Moderated conditions due to lower mass transfer coefficients resulted in thicker oxide layer thickness and then higher ECP, while moderated corrosion conditions due to higher oxidant concentrations resulted in larger hematite/magnetite rate and then higher ECP.     

Novel method for measuring cutoff wavelength of HE21-, TE01-and TM01-modes

A new measurement method for the cutoff wavelength of HE21-, TE01-and TM01 modes using a polariser is described. The experimental results show that higher measurement accuracy and sensitivity are obtained compared with the previous method.     

Water chemistry technology – one of the key technologies for safe and reliable nuclear power plant operation

Water chemistry control is one of the key technologies to establish safe and reliable operation of nuclear power plants. Continuous and collaborative efforts of plant manufacturers and plant operator utilities have been focused on optimal water chemistry control, for which, a trio of requirements for water chemistry should be simultaneously satisfied: (1) better reliability of reactor structures and fuel rods; (2) lower occupational exposure and (3) fewer radwaste sources. Various groups in academia have carried out basic research to support the technical bases of water chemistry in plants. The Research Committee on Water Chemistry of the Atomic Energy Society of Japan (AESJ), which has now been reorganized as the Division of Water Chemistry (DWC) of AESJ, has played important roles to promote improvements in water chemistry control, to share knowledge about and experiences with water chemistry control among plant operators and manufacturers and to establish common technological bases for plant water chemistry and then to transfer them to the next generation of plant workers engaged in water chemistry. Furthermore, the DWC has tried and succeeded arranging R&D proposals for further improvement in water chemistry control through roadmap planning. In the paper, major achievements in plant technologies and in basic research studies of water chemistry in Japan are reviewed. The contributions of the DWC to the long-term safe management of the damaged reactors at the Fukushima Daiichi Nuclear Power Plant until their decommissioning are introduced.