Lifetime reduction of a quantum emitter with quasiperiodic metamaterials

Enhancement of light-matter interaction of a quantum emitter with subwavelength quasiperiodic metamaterials is proposed and demonstrated. The quasiperiodic metamaterials consist of subwavelength metal-dielectric multilayers, which are arranged into a Fibonacci lattice. The influence of Fibonacci metamaterials (FM) on the dipole emission is analyzed with a semiclassical model. The local density of states near FM is evaluated and a characteristic mode in higher wave numbers is revealed; a strong enhancement of the decay rate was predicted. A lifetime measurement is carried out and a reduction of lifetime of quantum dots on the surface of FM is observed. The enhancement of light-matter interaction arises from the localized latticelike state inherent for self-similar quasiperiodic order

Direct measurement of a patient\u27s entrance skin dose during pediatric cardiac catheterization

Children with complex congenital heart diseases often require repeated cardiac catheterization; however, children are more radiosensitive than adults. Therefore, radiation-induced carcinogenesis is an important consideration for children who undergo those procedures. We measured entrance skin doses (ESDs) using radio-photoluminescence dosimeter (RPLD) chips during cardiac catheterization for 15 pediatric patients (median age, 1.92 years; males, n = 9; females, n = 6) with cardiac diseases. Four RPLD chips were placed on the patient\u27s posterior and right side of the chest. Correlations between maximum ESD and dose–area products (DAP), total number of frames, total fluoroscopic time, number of cine runs, cumulative dose at the interventional reference point (IRP), body weight, chest thickness, and height were analyzed. The maximum ESD was 80 ± 59 (mean ± standard deviation) mGy. Maximum ESD closely correlated with both DAP (r = 0.78) and cumulative dose at the IRP (r = 0.82). Maximum ESD for coiling and ballooning tended to be higher than that for ablation, balloon atrial septostomy, and diagnostic procedures. In conclusion, we directly measured ESD using RPLD chips and found that maximum ESD could be estimated in real-time using angiographic parameters, such as DAP and cumulative dose at the IRP. Children requiring repeated catheterizations would be exposed to high radiation levels throughout their lives, although treatment influences radiation dose. Therefore, the radiation dose associated with individual cardiac catheterizations should be analyzed, and the effects of radiation throughout the lives of such patients should be followed

非対称型ダブルバーメタマテリアルを用いたプラズモニックナノ共振器

要約のみTohoku University金森義明課

In vitro stemness characterization of radio-resistant clones isolated from a medulloblastoma cell line ONS-76

One-third of patients with medulloblastoma die due to recurrence after various treatments including radiotherapy. Although it has been postulated that cancer stem-like cells are radio-resistant and play an important role in tumor recurrence, the “stemness” of medulloblastoma cells surviving irradiation has not yet been elucidated. Using a medulloblastoma cell line ONS-76, cells that survived gamma irradiation were investigated on their “stemness” in vitro. From 10 500 cells, 20 radio-resistant clones were selected after gamma ray irradiation (5 Gy × two fractions) using the replica micro-well technique. These 20 resistant clones were screened for CD133 positivity by flow cytometry followed by side population assay, tumor sphere formation assay and clonogenic survival assay. Results revealed CD133 fractions were significantly elevated in three clones, which also exhibited significantly increased levels of tumor sphere formation ability and side population fraction. Clonogenic survival assay demonstrated that their radio-resistance was significantly higher than the parental ONS-76. This may support the hypothesis that a small number of cancer stem-like cells (CSCs) are the main culprits in local recurrence after radiotherapy, and disruption of the resistance mechanism of these CSCs is a critical future issue in improving the outcome of patients with medulloblastoma

Dose-dependent decrease in anti-oxidant capacity of whole blood after irradiation: A novel potential marker for biodosimetry

Many reports have demonstrated that radiation stimulates reactive oxygen species (ROS) production by mitochondria for a few hours to a few days after irradiation. However, these studies were performed using cell lines, and there is a lack of information about redox homeostasis in irradiated animals and humans. Blood redox homeostasis reflects the body condition well and can be used as a diagnostic marker. However, most redox homeostasis studies have focused on plasma or serum, and the anti-oxidant capacity of whole blood has scarcely been investigated. Here, we report changes in the anti-oxidant capacity of whole blood after X-ray irradiation using C57BL/6 J mice. Whole-blood anti-oxidant capacity was measured by electron spin resonance (ESR) spin trapping using a novel spin-trapping agent, 2-diphenylphosphinoyl-2-methyl-3,4-dihydro-2H-pyrrole N-oxide (DPhPMPO). We found that whole-blood anti-oxidant capacity decreased in a dose-dependent manner (correlation factor, r > 0.9; P < 0.05) from 2 to 24 days after irradiation with 0.5–3 Gy. We further found that the red blood cell (RBC) glutathione level decreased and lipid peroxidation level increased in a dose-dependent manner from 2 to 6 days after irradiation. These findings suggest that blood redox state may be a useful biomarker for estimating exposure doses during nuclear and/or radiation accidents

[原著］Prethymic Nylon Wool-Passed Bone Marrow Cells Can Make Distinction between Self and Non-Self X-Chromosome-Linked Gene Products (Xir Antigens) on the Stimulator Cells, Resulting in Regulation of the Generation of Cytotoxic T Lymphocytes in Mixed Lymphocyte Cultures

We have previously reported that nylon wool-passed bone marrow cells treated with anti-Thy.1 antibody and complement (Thy.1 NW-BM cells) had helper-like activity which could augment the generation of cytotoxic T lymphocytes (CTL). In this study, we determined the antigens to which these NW-BM cells responded and recognized. When a few responder lymph node (LN) cells and an excess of NW-BM responder cells from BIOBR (H-2^k B10 background) mice were cultured with stimulator spleen cells from either B10D2 (H-2^k, B10 background) or BALB/c (H-2^d, BALB/c background) mice, the number of CTL induced by the stimulation with BALB/c spleen cells was significantly higher than in those from B10D2 mice. When the cells from BALB.K (H-2^k. BALB/c background) mice were used as the responder, the results showed that B10D2 spleen cells were better stimulators than those of BALB/c. These results showed that NW-BM cells responded to the nonself allogeneic background gene products on the stimulator cells, but not to those of self, and that these responder NW-BM cells augmented CTL generation. We genetically analyzed the antigens that NW-BM cells recognized among many products derived from background genes. B10BR NWBM cells were well stimulated by (BALB.KXB10D2) F1 male spleen cells, but not by those of (B10D2×BALB.K) F1 males. On the contrary, BALB.K NW-BM cells were highly stimulated by (B10D2XBALB.K) F1 males, but not by (BALB.KXB10D2) F1 males. These results showed that NW-BM c?lIs had a strict preference for X-chromosome linked gene products (Xir antigens). We also showed that the augmenting ability of NW-BM cells was attributed to the Thy.1 population, and that BALB/c NW-BM cells possessing the H-2^d haplotype also responded preferentialy to nonself Xir antigens, To conclude, NW-BM cells could distinguish between self and non-self Xir antigens, resulting in regulation of the CTL response.論文http://purl.org/coar/resource_type/c_650

Influence of Couple Stresses on Stress Distributions in Rectangular Specimens Compressed Between Rigid Rough Platens

The present paper is concerned with the influence of couple stresses and the Poisson's ratios on the stress distributions in rectangular specimens compressed between rigid rough platens. An exact solution was obtained by the Fourier expansion method. The conclusions are as follows. 1) As the material parameter for bending rigidity in the couple stress theory approaches to zero, stresses in the specimen become closer to those in the classical theory. 2) The influence of couple stresses is limited near the boundaries of the specimen and fades out rapidly as it goes away from the boundaries. 3) The larger the material parameter for bending rigidity becomes, the more uniform stresses are expected to develop in the specimen. 4) The magnitude of shear stress acting on the perpendicular plane to the specimen axis is in general larger than that of shear stress acting on the plane parallel to the specimen axis. The shear stress in the classical theory approximately falls between the above two. 5) The Poisson's ratio has predominant influence on the stress distributions throughout the specimen. 6) The larger the Poisson's ratio is, the larger the magnitude of stresses becomes. The smaller the Poisson's ratio is, the more uniform stress distributions are expected. 7) As the Poisson's ratio increases, the apparent Young's modulus decreases. The larger the material parameter for bending rigidity is, the more rapidly the apparent Young's modulus decreases. 8) The influence of the Poisson's ratio and couple stresses on the apparent Young's modulus becomes less dominant as the height to width ratio of the specimen increases