Types of Damages in Fission-Neutron Irradiated Cu and Cu Dilute Alloys at 200℃

The damage structures in Cu and Cu based alloys neutron-irradiated at 200℃ were examined by transmission electron microscopy. Large dislocation loops of complex structure and small dot defects were formed in the specimens. The large dislocation loops were interstitial type. On the other hand, the small dot defects were vacancy type. They were stacking faulted tetrahedra. The damage structure in these metals evolves as follows. Interstitial atoms produced by neutron irradiation aggregate and grow to large complicated loops which will become finally dislocation lines by intersection of them with further irradiation, by absorbing interstitials subsequently produced. By the consumption of the interstitials to the sinks, vacancy concentration increases locally to be high enough to form vacancy defects

Metabolic syndrome correlates intracoronary stenosis detected by multislice computed tomography in male subjects with sleep-disordered breathing

<p>Abstract</p> <p>Background</p> <p>Sleep-disordered breathing (SDB), especially obstructive sleep apnea (OSA), has frequent complications include hypertension, dyslipidemia and insulin resistance based on abdominal obesity or excess visceral fat (called Syndrome Z). OSA is a potential risk factor for cardiovascular diseases. The clinical characteristics of Japanese OSA subjects with OSA remain unclear. The present study investigated prevalence and predictive factors of intracoronary stenosis detected by multislice computed tomography (MSCT) in Japanese male subjects with SDB/OSA.</p> <p>Findings</p> <p>The study (O-VFStudy) subjects were 39 Japanese men with SDB/OSA who underwent all-night cardiorespiratory monitoring with fully attended polysomnography, and moreover both fat computed tomography (CT) scan and 64-row MSCT coronary angiography. The prevalence of coronary stenosis in this selected population with SDB/OSA was 15%. Logistic regression analysis showed a significant relationship between age-adjusted CAD and metabolic syndrome (<it>p </it>< 0.05), but not serum adiponectin levels and nocturnal fall in adiponectin. Subjects with the metabolic syndrome had significantly higher prevalence of CAD (31.3 versus 4.3%, <it>p </it>= 0.033), and lower levels of serum adiponectin (4.5 ± 0.6 versus 6.4 ± 0.6 μg/mL, <it>p </it>= 0.014), compared with groups without the metabolic syndrome.</p> <p>Conclusions</p> <p>The present study describes that the prevalence of greater than 50% intracoronary stenotic lesions detected by MSCT was 15% and the metabolic syndrome was correlated with intracoronary stenosis detected by MSCT in Japanese SDB/OSA subjects.</p> <p>Trial Registration</p> <p>UMIN 000002997</p> <p><url>https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr.cgi?function=brows&action=brows&type=summary&recptno=R000003633&language=E</url>.</p

Muscle-specific deletion of BDK amplifies loss of myofibrillar protein during protein undernutrition

Ishikawa, T., Kitaura, Y., Kadota, Y. et al. Muscle-specific deletion of BDK amplifies loss of myofibrillar protein during protein undernutrition. Sci Rep 7, 39825 (2017). https://doi.org/10.1038/srep3982

Peroxisome proliferator-activated receptor α (PPARα) mRNA expression in human hepatocellular carcinoma tissue and non-cancerous liver tissue

<p>Abstract</p> <p>Background</p> <p>Peroxisome proliferator-activated receptor α (PPARα) regulates lipid metabolism in the liver. It is unclear, however, how this receptor changes in liver cancer tissue. On the other hand, mouse carcinogenicity studies showed that PPARα is necessary for the development of liver cancer induced by peroxisome proliferators, and the relationship between PPARα and the development of liver cancer have been the focus of considerable attention. There have been no reports, however, demonstrating that PPARα is involved in the development of human liver cancer.</p> <p>Methods</p> <p>The subjects were 10 patients who underwent hepatectomy for hepatocellular carcinoma. We assessed the expression of PPARα mRNA in human hepatocellular carcinoma tissue and non-cancerous tissue, as well as the expression of target genes of PPARα, carnitine palmitoyltransferase 1A and cyclin D1 mRNAs. We also evaluated glyceraldehyde 3-phosphate dehydrogenase, a key enzyme in the glycolytic system.</p> <p>Results</p> <p>The amounts of PPARα, carnitine palmitoyltransferase 1A and glyceraldehyde 3-phosphate dehydrogenase mRNA in cancerous sections were significantly increased compared to those in non-cancerous sections. The level of cyclin D1 mRNA tends to be higher in cancerous than non-cancerous sections. Although there was a significant correlation between the levels of PPARα mRNA and cyclin D1 mRNA in both sections, however the correlation was higher in cancerous sections.</p> <p>Conclusion</p> <p>The present investigation indicated increased expression of PPARα mRNA and mRNAs for PPARα target genes in human hepatocellular carcinoma. These results might be associated with its carcinogenesis and characteristic features of energy production.</p

The Effects of Gas Atoms on the Formation of Voids in Neutron-irradiated Metals

A series of experiments was carried out to study the effects of gas atoms on the formation of voids in neutron-irradiated pure Cu, Cu dilute (Al, Ni) alloys, pure Ni and SUS316L. Experiments were carried out with specimens from which dissolved residual gas atoms were removed by melting them in highly evacuated vacuum as 10^ Pa. It is found that in Cu, Cu-Al and SUS316L a residual gas has significant effects on the formation of voids while in Cu-Ni and Ni no effects were observed. Substantial component of gas evaporated from molten Cu, Cu-alloy and Ni was hydrogen. A large amount of nitrogen together with hydrogen evaporated from a molten SUS316L. Both types of residual gas free and as-received specimens were irradiated at the JMTR, JOYO, FFTF and EBR-II reactors. On the irradiation of low neutron fluence below 10^ n/cm^2, the number density of voids decreased in a residual gas free Cu. On the neutron irradiation at FFTF to a high fluence as 10^ n/cm^2, it was observed in pure Cu whose surface was shiny after the irradiation that the number density of voids increased in residual gas free specimen than that in as-received specimen. In the majority of pure Cu whose surface was contaminated severely by FFTF neutron irradiation to high neutron fluence, the difference of void formation was not observed between two types of specimens. This is due to resolving of gas atoms during a neutron irradiation. In Cu-5at.%Al, the formation of voids was remarkably suppressed in specimens of residual gas atom free. In Cu-5at.%Al irradiated at FFTF, many large voids were observed in as-received specimen while no void was observed in residual gas free specimens. In Cu-5at.%Ni, difference of the void formation between two type of specimens was not observed even after a low fluence of neutron irradiation at JMTR. Voids and many tangled dislocations were observed in irradiated Cu-5at.%Ni alloys. In as-received SUS316L which was irradiated at EBR-II to 10^ n/cm^2, small voids whose size is 10 nm in an average diameter were observed while no voids were observed in specimens of residual gas free. In pure Ni irradiated at the JMTR and EBR-II, the density and size of voids were similar in both type of specimens. The development of dislocation structure was not so remarkable in neutron-irradiated nickel. The atomistic process of the evolution of damage structure in neutron irradiated metals is discussed including the role of residual and transmutation generated gas atoms

中性子照射した金属中の点欠陥集合体の高温での動的挙動の電子顕微鏡観察による研究

研究期間:平成11-12年度 ; 研究種目:基盤研究C2 ; 課題番号:11650683原著には既発表論文の別刷を含む

Atomistic mechanism of nucleation and growth of voids in Cu studied by computer simulation

Shimomura and Mukouda [1] reported that a void could be formed by clustering of only vacancy. In fission-neutron-irradiated copper at 300°C to 7 x 10 17n/cm2 at Kyoto University Reactor (KUR), the number density of voids exceeds the number density of hydrogen and helium atoms that are generated by the transmutation reaction [2]. A copper foil irradiated in this experiment was prepared to be a very low content of residual gas atoms by melting in highly evacuated vacuum. It is reported by the present authors that vacancy clusters move as a cluster at high temperature and coalesce to a larger cluster [3, 4]. The objective of the present work is to show how a vacancy cluster can grow to a void by clustering of only vacancies at high temperature. This means that a void can be formed without an inclusion of gas atoms in vacancy clusters in neutron-irradiated copper at high temperature. Of course if gas atoms are included in a small vacancy cluster, a void formation is promoted significantly as reported on experiments of multi-ion beam irradiated copper [5]

Annihilation of interstitial atoms to dislocations in neutron-irradiated Cu and Ni at high temperature

When Cu and Ni were irradiated at 300°C by neutrons in a reactor, interstitial clusters decorate dislocations at a low fluence such as 5×1017 n/cm2. Computer simulation suggests that this is due to the accumulation of interstitial atoms in the dislocation strain field and also the difficulty of absorption of interstitials to extended dislocation which existed prior to irradiation. Interstitial clusters accumulated along dislocations coagulated to form dislocation loops in Cu and dipole loops which were along direction with a Burgers vector in Ni. These newly grown loops and dipoles can absorb interstitial clusters due to the unextended nature of these dislocations, and cause disappearance of decoration of interstitial clusters. Dislocations grew to a bow-out shape and was pinned at voids