Development of thermal fatigue testing apparatus with BWR water environment and thermal fatigue strength of austenitic stainless steels

A thermal fatigue testing apparatus was developed in order to clarify the fatigue behavior in BWR environment. Pressurized high and low temperature pure water were alternately supplied into an autoclave with a small cylindrical specimen. Then a fatigue specimen was subjected to homogeneous thermal stress through the wall thickness. Fatigue crack initiation behavior was observed with the replication method and compared with the mechanical fatigue strength performed in air and high temperature water. The thermal fatigue strength of type 304 and 316 nuclear grade (316NG) stainless steels agreed closely with the mechanical fatigue strength, when transforming the nominal stress amplitude to the fictitious stress amplitude by using the mean value of strain amplitudes for room temperature and 288°C.     

CCD-based range-finding sensor

Integration-time-based, time-domain computation provides an area-efficient way to process image information by directly handling photo-created charge during photo-sensing. We have fabricated and tested a CCD-based range-finding sensor which uses the time-of-flight method for range measurement. The sensor exploits two charge packets for light integration and detects the delay of the received light pulse relative to the transmitted light pulse. It has detected a 10 cm distance difference at the range of 150 cm in the dark background     

Reduction of the major swine xenoantigen, the alpha-galactosyl epitope by transfection of the alpha2,3-sialyltransferase gene

alpha2,3-Sialyltransferase represents a putative enzyme that reduces the Galalpha1-3Gal beta1-4GlcNAc-R (the alpha-galactosyl epitope) by intracellular competition with alpha1,3-galactosyltransferase for a common acceptor substrate. This study demonstrates that the overexpression of the alpha2,3-sialyltransferase gene suppresses the antigenicity of swine endothelial cells to human natural antibodies by 77% relative to control cells and by 30% relative to cells transfected with alpha1,2-fucosyltransferase, and in addition, it reduces the complement-mediated cell lysis by 75% compared with control cells and by 22% compared with cells transfected with alpha1, 2-fucosyltransferase. The mechanism by which the alpha-galactosyl epitope was reduced was also studied. Suppression of alpha1, 3-galactosyltransferase activity by 30-63% was observed in the transfectants with alpha2,3-sialyltransferase, and mRNA expression of the alpha1,3-galactosyltransferase gene was reduced as well. The data suggest that the alpha2,3-sialyltransferase effectively reduced the alpha-galactosyl epitope as well as or better than the alpha1, 2-fucosyltransferase did and that the reduction of the alpha-galactosyl epitope is due not only to substrate competition but also to an overall reduction of endogenous alpha1, 3-galactosyltransferase enzyme activity.     

Trajectory control of controlled-PM linear synchronous motor magnetic levitation vehicle—FEM dynamics simulations and experiments in mass-reduced-control mode

A novel magnetic levitation train system can be constructed by using a long-stator controlled-PM linear synchronous motor having propulsion and attractive-mode levitation functions and minimum loss. Realizing this system requires simplifying manufacture of the long-stator guideway. In the long-stator on the ground, semiclosed large slots are adapted and designed for one-turn coils of a waveform to be easily installed. The large slots cause the PM LSM detent forces to give strong influences on dynamic operations of the running vehicle. A two-dimensional FEM used for the dynamics simulations is capable of precisely analyzing the detent forces produced between the stator teeth and the PMs. This paper presents FEM dynamics simulations and experiments in mass-reduced-control mode of a 1/2 scale model magnetic levitation vehicle supported by small rubber rollers. The simulation model developed here includes the vehicle speed performance, position sensors and drag force due to friction between rubber roller and rail. The detent force problem in propulsion motion is successfully solved by adapting the feedback control of the vehicle propulsion based on the I₁₀-controlled method. The trajectory control is thus accomplished for the vehicle to follow speed and position patterns. The dynamics simulations are verified from the experiments. The simulation program proposed here enables us to investigate the magnetic levitation train system, including LSM design and vehicle dynamic operations.     

Study on the duration of pyuria after transurethral resection of prostate

Recent Canadian, American and European studies have reported increased ampicillin and trimethoprim/sulfamethoxazole resistance among urinary tract isolates of Escherichia coli. This trend suggests that a reevaluation of first- and second-line therapies for the treatment of community-acquired urinary tract infections is necessary. Mecillinam, a beta-lactam with preferential activity against gram-negative penicillin binding protein 2 (unlike other beta-lactams which preferentially bind gram-negative penicillin binding proteins 1a, 1b or 3), may offer clinically significant activity against ampicillin-resistant and trimethoprim/sulfamethoxazole-resistant E. coli. To test this assertion, the activity of mecillinam was compared with ampicillin, trimethoprim/sulfamethoxazole, nitrofurantoin and ciprofloxacin against 258 consecutive gram-negative urinary tract isolates collected at a Canadian tertiary care hospital. Mecillinam demonstrated significantly better activity than ampicillin and trimethoprim/sulfamethoxazole and significantly less activity than ciprofloxacin and nitrofurantoin against the 258 isolates tested. Against E. coli isolates specifically, mecillinam was significantly more active than ampicillin and trimethoprim/sulfamethoxazole (p < 0. 001) and as active as ciprofloxacin and nitrofurantoin. Mecillinam was active against 91.9% of ampicillin-resistant E. coli and 95.9% of trimethoprim/sulfamethoxazole-resistant E. coli. We conclude that mecillinam should be reevaluated for potential use in the treatment of community-acquired urinary tract infections.     

High prevalence of antibodies to glutamic acid decarboxylase in comparison to islet cell antibodies in patients with long-standing insulin-dependent diabetes mellitus

To elucidate the clinical significance of antibodies to glutamic acid decarboxylase (GAD Ab) compared to islet cell antibodies (ICA) in recent-onset and long-standing insulin-dependent diabetes mellitus (IDDM). We examined GAD Ab and ICA in 29 recent-onset and 85 long-standing patients with IDDM. GAD Ab was detected by a radioimmunoassay kit using purified pig brain GAD as an antigen. The prevalence of GAD Ab in the recent-onset diabetic patients was 55.2%, slightly lower than that of ICA (65.5%). In contrast, the prevalence of GAD Ab in long-standing diabetic patients was 42.4%, which was significantly higher than that of ICA (23.5%) (p < 0.01). GAD Ab were consistently detected in approximately 40% of patients with long-standing disease, while ICA decreased according to duration of disease. The GAD Ab titer in ICA-positive patients (mean +/- SD, 1588.2 +/- 6755.1; range, 6-38574) was significantly higher than that in ICA-negative patients (mean +/- SD, 13.4 +/- 17.9; and range, 5-72 units) (p < 0.001). These findings suggest that GAD Ab are more useful than ICA to know participation of immune disorders in long-standing patients with IDDM.     

Self-efficacy and learning experience of information education: in case of junior high school

The purpose of this study is to make clear the relationships between student’s self-efficacy and learning experience of information education in case of junior high school. Two investigations were implemented in this study. The aim of first investigation was to grasp the present status of students’ feeling of effectiveness of their learning experience in information education. Also, the aim of second investigation was to verify the relationships between students’ self-efficacy and the abilities for information utilizing that promoted in information education. The first investigation with a question: “What kind of a learning experience do you feel is useful in your life?” was conducted on 426 junior high school students. As a result, almost half of the students feel effectiveness of gaining computer-operating skills in “Information and Computer” class. Also, it is suggested that utilization of Internet could promote the feeling of effectiveness in current daily lives. In second investigation, the relationship between self-efficacy and abilities for information utilizing was examined by using multi-regression analysis on 544 junior high school students. As a result, abilities for information utilizing were affected from self-evaluation of “social position of abilities” and “positive attitude to activities” in self-efficacy. Also, self-efficacy was affected from “processing ability of information” and “creation ability of information” in abilities for information utilizing. By the results of these investigations, it is suggested that these two factors are formed as a gradual cycle which promote each other. From these results, some suggestions for improvement of classroom activities in information education were proposed.     

CRACK GROWTH ARRESTING PROPERTY OF A HOLE AND BRINELL-TYPE DIMPLE

Abstract— Fatigue tests of sheet specimens having a central crack were carried out to study the effects of holes and dimples on the arrest of fatigue crack propagation. Two holes were drilled at some distance from, and at either side of, a crack tip, and the dimple of a certain diameter was introduced by pressing steel balls in the specimen at a crack tip. Results showed that the two holes produced an increase in crack propagation life (about 3 times) when the holes were drilled at an appropriate distance. On the other hand, the effect of a dimple on the fatigue strength was remarkably large, i.e. in the greatest case a 2.2 times increase in the fatigue endurance limit of cracked specimens and about a 50 times increase in the crack propagation life, at stresses above the fatigue limit. The main reason for the remarkable recovery of fatigue strength was the residual compressive stresses produced by the dimple. To evaluate the effect of residual compressive stresses on the da/dN vs. δK relation, a simple model is proposed. By using this model, the effect of residual stresses on crack propagation can be estimated quantitatively. Furthermore, the fatigue life of dimpled specimens was estimated based on the model.     

Synthesis and characterization of liquid crystal photoresist

A thermotropic liquid crystal polymer with photosensitive groups (liquid crystal photoresist), copoly(4-methoxyphenyl) 4′-(2″-acroloyloxy ethoxy) benzoate (MPAEB)-4-vinylbenzyl cinnamate (VBC) was prepared, and its thermal behavior was characterized by a differential scanning calorimetry. The copolymer exhibited a liquid crystal mesophase between approximately 70°C and 120°C. In the mesophase, poly(MPAEB-VBC) (85/15) had a higher photo-crosslinking ability than that at room temperature and at 140°C, where the copolymer exhibited the isotropic phase. It was found that the liquid crystal photoresist had a high crosslinking ability owing to alignment of its photosensitive groups. © 1994 John Wiley & Sons, Inc.     

E.s.r. spectra of eastern oil shales

E.s.r. spectra of several oil shales from eastern and western USA have been measured at 9 and 25 GHz. The spectra of the western shales were similar to previously reported spectra and consist of a Mn²⁺ signal and a featureless organic signal. The eastern spectra consist of a V⁴⁺ signal and a complex and unusual organic signal consisting of at least four component signals. The organic signal has been characterized in terms of g factor, line-width and saturation characteristics. The effect of oxygen on the signal has also been examined. Electron nuclear double resonance (ENDOR) signals have been obtained from the organic signals of the eastern oil shales.