Characterization of the effect of ion irradiation on industrially produced GdBa₂Cu₃O₇−δ superconducting tapes using a slow positron beam

To investigate the effect of irradiation-induced defects on the superconducting characteristics of industrially produced superconductor—GdBa₂Cu₃O₇−δ (GdBCO)—coated conductors (CCs), we irradiated the GdBCO CCs with Au ions at 2 or 10 MeV and probed them using a slow positron beam. Vacancy clusters were detected in both unirradiated and irradiated GdBCO CCs. However, the effect of ion irradiation on the GdBCO CCs was characterized as a slight reduction in the positron annihilation rate with low-momentum electrons. We also found a correlation between the annihilation rate of low-momentum electrons and the superconducting transition temperature

c-ABL tyrosine kinase stabilizes RAD51 chromatin association

金沢大学がん研究所がん分子細胞制御The assembly of RAD51 recombinase on DNA substrates at sites of breakage is essential for their repair by homologous recombination repair (HRR). The signaling pathway that triggers RAD51 assembly at damage sites to form subnuclear foci is unclear. Here, we provide evidence that c-ABL, a tyrosine kinase activated by DNA damage which phosphorylates RAD51 on Tyr-315, works at a previously unrecognized, proximal step to initiate RAD51 assembly. We first show that c-ABL associates with chromatin after DNA damage in a manner dependent on its kinase activity. Using RAD51 mutants that are unable to oligomerize to form a nucleoprotein filament, we separate RAD51 assembly on DNA to form foci into two steps: stable chromatin association followed by oligomerization. We show that phosphorylation on Tyr-315 by c-ABL is required for chromatin association of oligomerization-defective RAD51 mutants, but is insufficient to restore oligomerization. Our findings suggest a new model for the regulation of early steps of HRR. © 2009 Elsevier Inc. All rights reserved

Human PSF concentrates DNA and stimulates duplex capture in DMC1-mediated homologous pairing

PSF is considered to have multiple functions in RNA processing, transcription and DNA repair by mitotic recombination. In the present study, we found that PSF is produced in spermatogonia, spermatocytes and spermatids, suggesting that PSF may also function in meiotic recombination. We tested the effect of PSF on homologous pairing by the meiosis-specific recombinase DMC1, and found that human PSF robustly stimulated it. PSF synergistically enhanced the formation of a synaptic complex containing DMC1, ssDNA and dsDNA during homologous pairing. The PSF-mediated DMC1 stimulation may be promoted by its DNA aggregation activity, which increases the local concentrations of ssDNA and dsDNA for homologous pairing by DMC1. These results suggested that PSF may function as an activator for the meiosis-specific recombinase DMC1 in higher eukaryotes

Filament formation and robust strand exchange activities of the rice DMC1A and DMC1B proteins

The DMC1 protein, a meiosis-specific DNA recombinase, catalyzes strand exchange between homologous chromosomes. In rice, two Dmc1 genes, Dmc1A and Dmc1B, have been reported. Although the Oryza sativa DMC1A protein has been partially characterized, however the biochemical properties of the DMC1B protein have not been defined. In the present study, we expressed the Oryza sativa DMC1A and DMC1B proteins in bacteria and purified them. The purified DMC1A and DMC1B proteins formed helical filaments along single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA), and promoted robust strand exchange between ssDNA and dsDNA over five thousand base pairs in the presence of RPA, as a co-factor. The DMC1A and DMC1B proteins also promoted strand exchange in the absence of RPA with long DNA substrates containing several thousand base pairs. In contrast, the human DMC1 protein strictly required RPA to promote strand exchange with these long DNA substrates. The strand-exchange activity of the Oryza sativa DMC1A protein was much higher than that of the DMC1B protein. Consistently, the DNA-binding activity of the DMC1A protein was higher than that of the DMC1B protein. These biochemical differences between the DMC1A and DMC1B proteins may provide important insight into their functional differences during meiosis in rice

Transient contact behavior of aqueous polymer solution droplets with transparent hot solid

In the metal forming industry, quench hardening is commonly used to strengthen steel products by rapidly cooling hot materials. One of the typical coolants used in the quench hardening process is an aqueous polymer solution. During the hardening process, several phenomena occur simultaneously, namely, coolant boiling, separation of the polymer from the aqueous solution, and formation of a polymer-enriched layer on the solid surface. The hydrodynamics and heat transfer characteristics of the coolant during the cooling process are complex in nature and remain unclear. The main objective of this study is to develop an experimental understanding of the collision and contact behavior of aqueous polymer solution droplets with a hot substrate. This research will serve as a fundamental reference work for the process of quench hardening using spray cooling. To fulfill this objective, a three-directional flash photography technique was developed. A transparent sapphire prism was used to observe the transient contact behavior of droplets with a hot solid, whose temperature was varied from 300 to 600 °C. A solution of 10 wt% polyoxyethylene-polyoxypropylene glycol with an average molecular weight of approximately 20, 000 was used as the test liquid. At a substrate temperature of 300 °C, jellylike polymer residue remained on the substrate. At 400 and 500 °C, a wet area appeared temporarily on the solid substrate soon after the droplet collision, but this area eventually disappeared because of the thermal decomposition of the polymer. At 600 °C, no wet area was seen. The lifetime of the temporary wet area decreased with an increase in the temperature of the solid but was almost independent of the impact inertia of droplets. In addition, in the case of the polymer solution droplet, the upper limit of the surface temperature for forming the wet area was around 580 °C, which was considerably higher than that in the case of a water droplet

Characterization of the effect of ion irradiation on industrially produced GdBa₂Cu₃O₇−δ superconducting tapes using a slow positron beam

To investigate the effect of irradiation-induced defects on the superconducting characteristics of industrially produced superconductor—GdBa₂Cu₃O₇−δ (GdBCO)—coated conductors (CCs), we irradiated the GdBCO CCs with Au ions at 2 or 10 MeV and probed them using a slow positron beam. Vacancy clusters were detected in both unirradiated and irradiated GdBCO CCs. However, the effect of ion irradiation on the GdBCO CCs was characterized as a slight reduction in the positron annihilation rate with low-momentum electrons. We also found a correlation between the annihilation rate of low-momentum electrons and the superconducting transition temperature

Associations between physical frailty and living arrangements in Japanese older adults living in a rural remote island : The Shimane CoHRE study

Background: Living arrangements have been known to be associated with physical frailty. However, the prevalence of frailty and its risk factors in remote islands is not understood. We examined the association between living arrangements and objectively measured frailty among older adults living in a remote island of Japan. Methods: Among older people living in Okinoshima, 656 older adults (75.6 ± 6.4 years) were analyzed. Physical frailty (robust, prefrailty, or frailty) was assessed using the 5-item frailty phenotype (unintentional weight loss, self-reported exhaustion, weakness, slow walking speed, and low physical activity). Physical functions (muscle mass, gait speed, and grip strength) were measured objectively. Results: The prevalence of frailty and prefrailty was 6.6% and 43.8%, respectively. Living with a spouse resulted in a significantly lower prevalence of frailty (p < 0.001) compared with other living arrangements. All objectively measured physical functions among those who lived with a spouse were significantly superior to those who lived with family or alone (p < 0.001). Multinomial logistic regression showed that living alone was significantly associated with frailty (odds ratio [OR] 2.36, 95% confidence interval [CI] 1.07–5.24) and prefrailty (OR 1.75, 95% CI 1.14–2.69) after adjusting for all covariates. Conclusion: The prevalence of frailty on remote islands seemed similar to that in urban areas. Older people living in remote islands might be able to maintain their physical health. Furthermore, living alone may correlate with increased risks of frailty and prefrailty. Among elderly individuals on remote islands, living with a spouse might be desirable to prevent (pre)frailty

Associations between dairy consumption and the physical function in Japanese community-dwelling older adults : The Shimane CoHRE study

Objectives: We investigated sex differences in the associations between dairy consumption and the physical function among community-dwelling older adults. Methods: Six hundred and fifty-six older adults (75.6 ± 6.4 years old) participated in this study. Dairy consumption (5-item Likert score) and the physical function (gait speed, handgrip strength, and skeletal muscle mass) were measured. The linear and quadratic associations between dairy consumption and the physical function measures were examined by a multiple linear regression analysis adjusted for covariates. Results: Among women, an increased dairy consumption was significantly linearly associated with greater hand-grip strength and faster gait speed (both p<0.05) after adjusting for covariates. Among men, dairy consumption was not associated with the physical function measures. Dairy consumption was not associated with the muscle mass in either sex. Conclusions: Increased dairy consumption was associated with a superior physical function in older women

Total elbow arthroplasty for hemophilic osteoproliferative elbow arthritis with severe flexion contracture: A case report

Total elbow arthroplasty is effective for pain relief and the functional improvement of severe symptomatic hemophilic osteoproliferative arthropathy. Nevertheless, high complication rates have been reported. This report describes clinical results obtained at 30-month follow-up of total elbow arthroplasty in a hemophilic patient with severe flexion contracture. A 50-year-old patient with advanced left elbow hemophilic arthropathy underwent unlinked total elbow arthroplasty. He had sustained an intraoperative fracture of the medial part of a supracondylar humerus complication. To control perioperative bleeding, strict factor VIII replacement therapy was performed under the guidance of hematologists. The total elbow range of motion was 35° preoperatively, but it had improved to 110° postoperatively. The Patient-Rated Elbow Evaluation Japanese version score, which was 53.7 preoperatively, improved to 10.7 postoperatively. During the 30 months after operation, no complication occurred. Good clinical results have been obtained under close collaboration with hematologists and close patient adherence following treatment