Applications of probabilistic fracture mechanics to FBR components

A probabilistic fracture mechanics code which evaluates fracture probability of a plate model with an elliptical surface crack caused by creep-fatigue crack growth has been developed. The code named PCCF (Probabilistic Fracture Mechanics Code for Creep-Fatigue Crack Growth) uses simplified methods of C^* and J-integral for evaluation of creep-fatigue crack growth and a stratified sampling method for two input variables to improve the solution convergency. According to the test analyses focused on an applied stress level using PCCF code, leak probability is sensitive to a stress level and increases rapidly when an applied stress is close to a yield stress level.     

Radical formation site of cerebral complex I and Parkinson's disease

Paraquat was reduced to the paraquat radical via complex I in bovine cerebral mitochondria and accelerated lipid peroxidation. Thirty-kilodalton subunit of complex I was considered to be the radical formation site, because of its marked destruction by the paraquat radical. The lipid peroxidation by the paraquat radical was suppressed not only by superoxide dismutase (SOD) but also by mannitol. The destruction of complex I subunits via lipid peroxidation must have been caused by the hydroxyl radical which was formed from the superoxide radical. The same phenomenon was observed by using 1-methylnicotinamide (MNA), which contains the same partial structure as paraquat in itself and is metabolized from nicotinamide in a living body. We observed NADH oxidation by MNA via cerebral complex I (Km = 26.3 mM), and MNA destroyed some complex I subunits, especially 30-kilodalton protein. Paraquat might be useful for studying the pathogenesis of Parkinson's disease (PD) in vitro, and MNA is expected to be one of the causal substances of PD from the viewpoint of the oxidative stress theory.     

Fracture of filaments and its influence on critical current and residual strength of fatigued Nb-Ti/Cu superconducting composite

Fatigue behavior at room temperature and its influence on critical current at 4.2 K and residual strength at room temperature of multifilamentary Nb-Ti/Cu superconducting composite wire with a filament volume fraction of 0.49 (copper ratio of 1.04) were studied. The fatigue crack nucleated in the copper in the circumferential region and propagated stably into the inner region, causing fracture of the Nb-Ti filaments in the late stage of the fatigue life. Once the fracture of the filaments started, the number of the fractured filaments increased steeply with increasing number of stress cycles, and correspondingly, the current-transportable and stress-carrying capacity of the composite decreased steeply. In this process, both the critical current and residual strength of the fatigued composite decreased nearly linearly with decreasing fraction of surviving filaments. Thus, the critical current of the fatigued composite was proportional to residual strength as a first approximation.     

Jejunal perforation caused by blunt abdominal trauma in a patient with Crohn's disease: report of a case

We report herein the case of a 23-year-old man with Crohn's disease who was found to have a perforated small bowel following blunt abdominal trauma sustained in a traffic accident. The general findings of diffuse peritonitis were identified by physical examination, and a plain X-ray film showed free air in the abdominal cavity. An emergency laparotomy was performed which revealed three perforated ulcers in the affected intestine. An abrupt increase in intraluminal pressure due to the striking force of the steering wheel to the abdomen was assumed to have been the cause of these perforations.     

Oxysterols found in opacified cornea of fish

We describe a new concept implicating oxidized cholesterol derivatives and very long-chain fatty acids as possible factors in the development of corneal opacification after death. Corneal tissues, removed from both fresh and stale fish eyes, were examined for cholesterol derivatives and fatty acids after methanolysis of lipids. Cholesta-3,5-dien-7-one, cholest-4-en-3-one, hexacosanoic acid, and hexacosenoic acid were identifiedvia gas chromatography/mass spectrometry in opacified corneas, but not in significant amounts in fresh ones. The present study confirmed the presence of lipid hydrolysis and a peroxidation process in the opacified cornea.     

Proton nuclear magnetic resonance and Raman spectroscopic studies of Japanese sake, an alcoholic beverage

The hydrogen-bonding property of water--ethanol in Japanese sake, a kind of brewage, was examined on the basis of both (1)H NMR chemical shifts of the OH of water--ethanol and the Raman OH stretching spectra. In 20% (v/v) EtOH-H(2)O solution, amino acids as well as organic acids caused low-field chemical shifts, i.e., the development of a hydrogen-bonding structure. Additional functional groups, apart from the essential amino- and carboxyl groups, in amino acids caused differences in their effects. The low-field chemical shifts caused by solutes were demonstrated under constant pH conditions maintained by sodium hydrogen citrate. Using both the measurement of (1)H NMR chemical shifts and Raman OH stretching spectra, the strength of the hydrogen bond of water--ethanol in Japanese sake products was found to be correlated with the total concentration of organic acids and amino acids. Glucose or saccharides should not have a strengthening effect on the hydrogen bond of water--ethanol. The effects of the main inorganic ions and amines were also discussed. It was concluded that chemical components originating from the starting material, rice, or products produced by microorganisms during the ethanol fermentation affect the hydrogen-bonding structure in Japanese sake.     

Markerless visual servo control of a servosphere for behavior observation of a variety of wandering animals

ABSTRACT

Servospheres are robotized observation equipments that produce endless fields for behavior observation of wandering animals. This paper first proposes a markerless visual tracking technique for estimation of the position and the heading direction of wandering animals, since existing techniques for servospheres require special markers or do not estimate the heading direction. The proposed markerless visual tracking technique is then integrated with a visual servo controller for a servosphere. The integrated markerless visual servo controller is available for wandering animals whose shapes in the image plane are represented by long bodies and thinner parts than their bodies. This paper demonstrates that the proposed controller is available for ants, crickets, mantises and spiders, while the shapes of their bodies and legs are different from each other.     

Histological and electrophysiological analysis of the peripheral nerve allografts using an immunosuppressive agent

In peripheral nerve allografts, use of an immunosuppressive agent is one of the ways of reducing nerve rejection. FK506 is a newly discovered substance, extracted from Streptomyces tsukubaensis, and has strong immunosuppressive effects. In the present study, immunosuppressive effects of FK 506 were examined using allografts of rat sciatic nerves. Good nerve regeneration was demonstrated through 12 weeks in this model. The immunosuppressed group gained weight over the course of the experiment. Another study was performed to observe the histological changes caused by ceasing the administration of FK506. Administration of FK506 was terminated 12 weeks after grafting. At 8 weeks after cessation, cellular infiltration and large unmyelinated axons were observed in the extended subperineurial space of grafts. At 12 weeks, histological characteristics of rejection were not observed. In the electrophysiological study, the temporal dispersions were recorded at 4 and 8 weeks. However, the normal electrophysiological waves were recorded at 12 weeks after cessation. It was concluded that FK506 is effective for preventing rejection of nerve allografts without any serious side effects on rats, and findings of total rejection of grafts were not recognized after ceasing the administration of FK 506. In peripheral nerve allografts, short-term administration of an immunosuppressive agent is sufficient to lead to good nerve regeneration.     

Computer-generated holograms to produce high-density intensity patterns

A computer-generated hologram consisting of N x N resolution cells produces a reconstructed image consisting of N x N sampling points. Since the width of the primary peaks in the point-spread function is twice the pitch of the sampling points, the intensity at intermediate points between the sampling points depends on the interference between the sampling points. Carefully controlling the complex amplitudes of the sampling points makes it possible to control the intensity not only at the sampling points but also at the intermediate points; the intensity of the reconstructed image can be controlled at 2N x 2N points. Preliminary experiments demonstrating the generation of high-density intensity patterns were performed.