Growth of GaN films on nitrided GaAs substrates using hot-wire CVD

Epitaxial growth of cubic-type gallium nitride (c-GaN) by hot-wire CVD on GaAs(100) substrates was investigated. Prior to the epitaxial growth, a nitridation layer was formed using ammonia plasma generated by electron cyclotron resonance (ECR). It was found that the crystal phase of the epitaxial layer was predominantly determined by that of the nitrided layer. The best nitridation condition using ECR plasma for the growth of the GaN films with preponderant cubic-type structure was obtained.     

Preparation of polysilsesquioxane grafted thermoresponsive polymer by use of mercapto group

The polysilsesquioxane having mercapto and phenyl groups (PMPSQ) was prepared from the corresponding trimethoxysilanes by co-condensation under basic conditions. The mercapto groups on PMPSQ were utilized as the initiators for the graft polymerization of N-isopropylacrylamide (NIPAM) with the comonomer such as N,N-dimethylacrylamide (DMAA) or hydroxyethyl acrylate under UV irradiation. The grafting of the copolymers proceeded effectively to give the functionalized polysilsesquioxane derivatives, in which the monomer unit ratios almost reflected the feed molar ratios of the monomers and no formation of gel product was observed. These grafted polysilsesquioxanes could be dissolved in water and showed the property of thermoresponsive gel formation.     

Development of high-strength (780 n/mm2) steel for building systems

The national project, initiated by the Comprehensive Scientific Technology Conference in the Cabinet Office, entitled “Development of New Structural systems Using Innovative Structural Materials” has two objectives: The first objective is to develop and produce new innovative steel materials. The second is to develop a new structural system using the new steel. This paper describes the production specification and the chemical composition. The required mechanical properties and test results conducted on the new steel that is produced are also presented.     

Preface

Journal of Materials Synthesis and Processing -     

Evaluation of Triage screening for drugs of abuse in postmortem blood and urine samples

BACKGROUND: Impaired changes in gastric epithelium proliferation have been described in Helicobacter pylori infection, and a progressive increase of proliferating cells has been shown with the progression of mucosal lesions. AIMS: Purpose of this investigation was to study the effect of eradication on bacterium-induced proliferative changes, evaluated by the proliferating cell nuclear antigen labelling index (PCNA LI) and its relationship to the ras oncoprotein p21, involved in early events of gastric carcinogenesis. PATIENTS AND METHODS: This retrospective study was performed, before and after therapy, in five different groups of patients with progressive stages of Helicobacter pylori damage (N: normality; HG: histological gastritis with normal endoscopy; EHG: histological gastritis with endoscopic chronic erosions; CIM: complete intestinal metaplasia; IIM: incomplete intestinal metaplasia). RESULTS: Six months after eradication, a normalization of PCNA LI was observed in the areas of gastritis, but not in those of intestinal metaplasia, which showed on unchanged type. Moreover, immunohistochemical membrane expression of ras oncoprotein p21 was only associated to intestinal metaplasia. The protein was also expressed in the cytoplasm in 3 patients with incomplete type. CONCLUSIONS: These results suggest that the development of intestinal metaplasia may be associated with an alteration in the control of gastric epithelium proliferation and could represent an initial stage in gastric carcinogenesis. Nevertheless, further genetic changes are necessary for a complete progression to neoplastic disease. A long-term follow-up on extension, type, proliferative situation and oncoprotein expression in areas of intestinal metaplasia may be helpful to explain whether the present data provide new information on the mechanism of Helicobacter pylori induced gastric carcinogenesis.     

Nonparametric preventive maintenance optimization models under earning rate criteria

The expected profit is frequently used as an optimality criterion in manufacturing and maintenance operations. In this paper, we consider the optimal preventive maintenance policy and the optimal repair limit policy which maximize the expected earning rates for one-unit systems subject to failure and repair, respectively. In particular, the total time on test concept is used to directly estimate the optimal policies from empirical sample data. The proposed methods provide geometrical interpretations of the underlying probabilistic problems to practitioners as well as nonparametric estimators of the optimal maintenance strategies.     

Clinical study of gasless laparoscopic adrenalectomy in 17 cases--comparison between laparoscopic adrenalectomy with and without pneumoperitoneum

PURPOSE: To determine the efficiency of gasless laparoscopic adrenalectomy, this procedure was compared to that with pneumoperitoneum. PATIENTS AND METHODS: Between February 1994 and December 1996, 17 gasless laparoscopic adrenalectomy were performed in 5 men and 12 women, 36 to 79 years old. Clinical diagnosis was primary aldosteronism in 8, pheocromocytoma in 2, incidentaloma in 4 and adrenal cyst in 3. When gasless laparoscopic adrenalectomy was performed, the laparoscope was inserted through the upper margin of the umbilicus by open laparotomy. To create a workable space, a 1.2 mm Kirschner wire was advanced subcutaneously below the costal arch and attached to a retractor. Operating time, estimated blood loss, changes of the end tidal CO2 concentration during operation, operative complications and postoperative course were compared to those with pneumoperitoneum in 12 cases. RESULTS: In both procedures, satisfying workable spaces were created in all cases. The mean operating time and estimated blood loss were 245 min and 201 ml without pneumoperitoneum, 317 min and 274 ml with pneumoperitoneum, respectively. The mean changes of end tidal CO2 concentration during operation were 3.2 mmHg without pneumoperitoneum and 5.1 mmHg with pneumoperitoneum. As operative complications, open operations were required in 2 cases (1 without pneumoperitoneum and another with pneumoperitoneum) to control intraoperative bleeding. They had the histories of transabdominal operations. Postoperative bleeding was observed in 2 cases (1 without pneumoperitoneum and another with pneumoperitoneum). One of them (with pneumoperitoneum) needed surgical management for hemostasis. Fever over 38 degrees C that occurred in 1 case with pneumoperitoneum appeared to be absorption fever. No differences were observed in the number of the days to the start of oral intake and for postoperative hospitalization between the two groups. CONCLUSIONS: Gasless laparoscopic adrenalectomy is available for most adrenal tumors. Suction could be used unrestrictedly and there were no hemodynamic or ventilatory effects due to pneumoperitoneum. This procedure appears to be safe and advantageous for the treatment of most adrenal tumors.     

Improvement of thermal interruption capability in self‐blast interrupting chamber for new 245‐kV 50‐kA GCB

Current zero measurements are performed for 245 kV‐50 kA‐60 Hz short line fault (L90) interruption tests with a self‐blast interrupting chamber (double‐volume system) which has the interrupting capability up to 245 kV‐50 kA‐50 Hz L90. Lower L90 interruption capability is observed for longer arcing time although very high pressure rise is obtained. It may be caused by higher blowing temperature and lower blowing density for longer arcing time. Interruption criteria and an optimization method of the chamber design are discussed to improve L90 interruption capability with it. The new chambers are designed at 245 kV‐50 kA‐60 Hz to improve gas density in thermal volume for long arcing time. 245 kV‐50 kA‐60 Hz L90 interruptions are performed with the new chamber. The suggested optimization method is an efficient tool for the self‐blast interrupting chamber design although study of computing methods is required to calculate arc conductance around current zero as a direct criterion for L90 interruption capability with higher accuracy. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(1): 9–17, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20743     

Design Guidelines of FRP Reinforced Concrete Building Structures

The “Design Guidelines of FRP Reinforced Concrete Building Structures” was established in 1993 as one of the final outputs of the research committee on fiber-reinforced plastic (FRP) reinforced concrete building structures organized under the Japanese Ministry of Construction's research and development project titled: “Effective Use of Advanced Construction Materials (1988–92).” These Guidelines are a translation of the Japanese guidelines. They describe the design concept for nonprestressed concrete structures reinforced with FRP rebars, and the calculation equations are all relegated to the commentaries due to lack of design data on FRP reinforced concrete structures. A limit-state design method has been adopted under the guidelines. Among the subjects covered are overview, design method, materials, loads and combination, stress and deformation, ultimate state design, serviceability state design, structural requirement, and testing methods for the tensile strength and bond strength of materials. “The Design Guidelines for FRP Prestressed Concrete Members” is separate from these guidelines.     

Torque and suspension force in a bearingless switched reluctance motor

Bearingless switched reluctance motors, which can control rotor radial positions with magnetic force, have been proposed. The bearingless switched reluctance motors are characterized by integration of switched reluctance motors and magnetic bearings. These motors have two kinds of stator windings composed of motor main windings and suspension windings in the same stator in order to produce suspension force that can realize rotor shaft suspension without mechanical contacts or lubrication. For successful stable operation, accurate theoretical formulas of instantaneous torque and suspension force are necessary to a rotational speed controller and a rotor radial position controller. This paper derives the theoretical formulas of the instantaneous torque and the suspension force from an assumption of simple permeance distribution. This derivation process makes an assumption that fringing fluxes are distributed on elliptical lines. It is shown with experimental results that the derived theoretical formulas are very accurate in terms of practical application. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 157(2): 72–82, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20157