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Journal Articles

Flexible heat-flow sensing sheets based on the longitudinal spin Seebeck effect using one-dimensional spin-current conducting films

Kirihara, Akihiro*; Kondo, Koichi*; Ishida, Masahiko*; Ihara, Kazuki*; Iwasaki, Yuma*; Someya, Hiroko*; Matsuba, Asuka*; Uchida, Kenichi*; Saito, Eiji; Yamamoto, Naoharu*; et al.

Scientific Reports (Internet), 6, p.23114_1 - 23114_7, 2016/03

 Times Cited Count:26 Percentile:7.97(Multidisciplinary Sciences)

Heat-flow sensing is expected to be an important technological component of smart thermal management in the future. Conventionally, the thermoelectric (TE) conversion technique, which is based on the Seebeck effect, has been used to measure a heat flow by converting the flow into electric voltage. However, for ubiquitous heat-flow visualization, thin and flexible sensors with extremely low thermal resistance are highly desired. Recently, another type of TE effect, the longitudinal spin Seebeck effect (LSSE), has aroused great interest because the LSSE potentially offers favourable features for TE applications such as simple thin-film device structures. Here we demonstrate an LSSE-based flexible TE sheet that is especially suitable for a heat-flow sensing application. This TE sheet contained a Ni$$_{0.2}$$Zn$$_{0.3}$$Fe$$_{2.5}$$O$$_4$$ film which was formed on a flexible plastic sheet using a spray-coating method known as ferrite plating. The experimental results suggest that the ferrite-plated film, which has a columnar crystal structure aligned perpendicular to the film plane, functions as a unique one-dimensional spin- current conductor suitable for bendable LSSE-based sensors. This newly developed thin TE sheet may be attached to differently shaped heat sources without obstructing an innate heat flux, paving the way to versatile heat-flow measurements and management.

Journal Articles

Epigenetic modifier as a potential radiosensitizer for heavy-ion therapy on malignancy, 2

Saito, Katsuyo*; Funayama, Tomoo; Kobayashi, Yasuhiko; Murakami, Takashi*

JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 83, 2015/03

Epigenetic modifiers, such as histone deacetylase inhibitors (HDACi) and DNA methyltransferase inhibitors, have emerged recently as promising anticancer agents and it has been expected that epigenetic modifiers may enhance the effect of other cancer therapeutics including radiotherapy. Therefore, we investigated whether the use of epigenetic modifiers could sensitize melanoma cells for the heavy-ion therapy. Murine B16F10 melanoma cells were treated with investigational or comparator epigenetic modifier, then exposed to carbon ions of JAEA-Takasaki. After irradiation, the viabilities of cells were evaluated by colony formation assay. Treatment of B16F10 melanoma cells with HDACi trichostatin A (TSA) in combination with heavy-ion radiation provided enhanced inhibition of colony formation. The data suggest that combination of an epigenetic modifier TSA together with heavy-ion therapy may provide improved therapeutic responses in melanoma patients.

Journal Articles

Genetic changes in progeny of bystander human fibroblasts after microbeam irradiation with X-rays, protons or carbon ions; The Relevance to cancer risk

Autsavapromporn, N.*; Plante, I.*; Liu, C.*; Konishi, Teruaki*; Usami, Noriko*; Funayama, Tomoo; Azzam, E.*; Murakami, Takeshi*; Suzuki, Masao*

International Journal of Radiation Biology, 91(1), p.62 - 70, 2015/01

 Times Cited Count:15 Percentile:5.53(Biology)

Radiation-induced bystander effects have important implications in radiotherapy. Their persistence in normal cells may contribute to risk of health hazards, including cancer. This study investigates the role of radiation quality and gap junction intercellular communication (GJIC) in the propagation of harmful effects in progeny of bystander cells. Confluent human skin fibroblasts were exposed to microbeam radiations with different linear energy transfer (LET) by which 0.036$$sim$$0.4% of the cells were directly targeted by radiation. Following 20 population doublings, the cells were harvested and assayed for micronucleus formation, gene mutation and protein oxidation. The results showed that expression of stressful effects in the progeny of bystander cells is dependent on LET.

Journal Articles

Longitudinal spin Seebeck effect; From fundamentals to applications

Uchida, Kenichi*; Ishida, Masahiko*; Kikkawa, Takashi*; Kirihara, Akihiro*; Murakami, Tomoo*; Saito, Eiji

Journal of Physics; Condensed Matter, 26(34), p.343202_1 - 343202_15, 2014/08

 Times Cited Count:106 Percentile:14.34(Physics, Condensed Matter)

Journal Articles

Radiation-quality-dependent bystander effects induced by the microbeams with different radiation sources

Suzuki, Masao*; Autsavapromporn, N.*; Usami, Noriko*; Funayama, Tomoo; Plante, I.*; Yokota, Yuichiro; Muto, Yasuko*; Suzuki, Michiyo; Ikeda, Hiroko; Hattori, Yuya; et al.

Journal of Radiation Research, 55(Suppl_1), P. i54, 2014/03

Journal Articles

Gap junction communication and the propagation of bystander effects induced by microbeam irradiation in human fibroblast cultures; The Impact of radiation quality

Autsavapromporn, N.*; Suzuki, Masao*; Funayama, Tomoo; Usami, Noriko*; Plante, I.*; Yokota, Yuichiro; Muto, Yasuko*; Ikeda, Hiroko; Kobayashi, Katsumi*; Kobayashi, Yasuhiko; et al.

Radiation Research, 180(4), p.367 - 375, 2013/10

 Times Cited Count:39 Percentile:6.65(Biology)

We investigated the role of gapjunction intercellular communication (GJIC) in the propagation of stressful effects in confluent normal human fibroblast cultures wherein only 0.036-0.144% of cells in the population were traversed by primary radiation tracks. Confluent cells were exposed to graded doses from X ray, carbon ion, neon ion or argon ion microbeams in the presence or absence of an inhibitor of GJIC. After 4 h incubation, the cells were assayed for micronucleus (MN) formation. Micronuclei were induced in a greater fraction of cells than expected based on the fraction of cells targeted by primary radiation, and the effect occurred in a dose-dependent manner with any of the radiation sources. Interestingly, the inhibition of GJIC depressed the enhancement of MN formation in bystander cells from cultures exposed to high-LET radiation but not low-LET radiation. The results highlight the important role of radiation quality and dose in the observed effects.

Journal Articles

Resonant X-ray scattering of PrRu$$_4$$P$$_{12}$$

Ishii, Kenji; Tsutsui, Satoshi*; Hao, L.*; Hasegawa, Tomoo*; Iwasa, Kazuaki*; Tsubota, Masami; Inami, Toshiya; Murakami, Yoichi*; Saha, S. R.*; Sugawara, Hitoshi*; et al.

Journal of Magnetism and Magnetic Materials, 310(2, Part1), p.e178 - e180, 2007/03

PrRu$$_4$$P$$_{12}$$ shows a metal-insulator (MI) transition at $$T_{mathrm MI} simeq$$ 62 K accompanied by a structural phase transition. Because LaRu$$_4$$P$$_{12}$$ without $$4f$$ electrons does not shows the MI transition, $$4f$$ electrons in the Pr atom plays an important role in the transition. In order to elucidate a modulation of electronic states of Pr, we have carried out a resonant X-ray scattering study of PrRu$$_4$$P$$_{12}$$ at Pr $$L_2$$- and $$L_3$$-edges. Below $$T_{mathrm MI}$$, resonant signal at the absorption main-edge was successfully observed at the superlattice reflections of the modulation vector $$vec{q}=(1,0,0)$$ in addition to the energy-independent component from the lattice distortion. Because the reflection contains the difference of anomalous scattering factors between two Pr atoms in the unit cell, two different electronic states are actually ordered below $$T_{MI}$$. Furthermore we found that the polarization of X-ray is mostly unrotated even at the resonance, which indicates that the resonant scattering in PrRu$$_4$$P$$_{12}$$ is almost isotropic.

Oral presentation

Resonant X-ray scattering of PrRu$$_4$$P$$_{12}$$

Ishii, Kenji; Tsubota, Masami; Inami, Toshiya; Tsutsui, Satoshi*; Hao, L.*; Hasegawa, Tomoo*; Iwasa, Kazuaki*; Murakami, Yoichi; Sugawara, Hitoshi*; Saha, S. R.*; et al.

no journal, , 

PrRu$$_4$$P$$_{12}$$ shows a metal-insulator (MI) transition at $$T_{mathrm MI} simeq$$ 62 K accompanied by a structural phase transition. Because LaRu$$_4$$P$$_{12}$$ without $$4f$$ electrons does not shows the MI transition, $$4f$$ electrons in the Pr atom plays an important role in the transition. In order to elucidate a modulation of electronic states of Pr, we have carried out a resonant X-ray scattering study of PrRu$$_4$$P$$_{12}$$ at Pr $$L_2$$- and $$L_3$$-edges. Below $$T_{mathrm MI}$$, resonant signal at the absorption main-edge was successfully observed at the superlattice reflections of the modulation vector $$vec{q}=(1,0,0)$$ in addition to the energy-independent component from the lattice distortion. Because the reflection contains the difference of anomalous scattering factors between two Pr atoms in the unit cell, two different electronic states are actually ordered below $$T_{MI}$$. Furthermore we found that the polarization of X-ray is mostly unrotated even at the resonance, which indicates that the resonant scattering in PrRu$$_4$$P$$_{12}$$ is almost isotropic.

Oral presentation

Induction of cell killing by bystander effect with argon ion microbeam irradiation

Suzuki, Masao*; Autsavapromporn, N.*; Funayama, Tomoo; Yokota, Yuichiro; Muto, Yasuko*; Ikeda, Hiroko; Suzuki, Michiyo; Hattori, Yuya; Sakashita, Tetsuya; Kobayashi, Yasuhiko; et al.

no journal, , 

To determine signal transduction factors that are expected to be secreted from microbeam-irradiated cells, the time course analysis of cell killing effect in microbeam irradiated cell population was carried out. To irradiate cell with heavy-ion microbeam, a collimating heavy-ion microbeam system of JAEA-Takasaki was used. After microbeam irradiation, the samples were incubated for 0.5, 3, 24 hours respectively, and the cell killing effect of the microbeam irradiation were measured by colony formation assay. The result suggested that some factors, which induces bystander cell killing, were secreted after argon-ion microbeam, and the factor can be inhibited by the addition of gap-junction inhibitor and DMSO, but not by the ascorbic acid.

Oral presentation

Late effects in the progeny of bystander human cells are dependent on radiation quality; The Relevance to cancer risk

Autsavapromporn, N.*; Plante, I.*; Liu, C.*; Konishi, Teruaki*; Usami, Noriko*; Funayama, Tomoo; Azzam, E.*; Murakami, Takeshi*; Suzuki, Masao*

no journal, , 

Confluent human skin fibroblasts (NB1RGB) were exposed to various types of microbeam with a different linear energy transfer (LET) at mean absorbed doses 0.4 Gy, wherein 0.036-0.4% of the cells were targeted by IR. Following 20 populations post-irradiation, the cells were harvested and assayed for micronucleus formation, mutation assay and protein oxidation. The progeny of bystander cells exposed to X rays and protons showed the persistence of oxidative stress, and correlate with the increased micronucleus formation and mutant fraction. However, such effects were not observed after irradiation by carbon ions. Interestingly, inhibition of GJIC mitigated the damaging effects in the progeny of bystander cells exposed to protons and carbon ions but not X rays. These data show carbon ions can reduce cancer risk after microbeam irradiation compared with X rays or protons, and GJIC may be a critical mediator in the observed effect.

Oral presentation

P53-dependent cell-killing effect via bystander effect using carbon-ion microbeams simulating the spot scanning system with pencil beams at HIMAC

Suzuki, Masao*; Funayama, Tomoo; Yokota, Yuichiro; Suzuki, Michiyo; Ikeda, Hiroko; Sakashita, Tetsuya; Kobayashi, Yasuhiko; Murakami, Takeshi*

no journal, , 

We irradiated either 4-cell lines with wild-type P53 or 4-cell lines with mutated-type P53 using the microbeams of JAEA-Takasaki collimated by 20$$mu$$m in diameter. We can easily estimate the number of the directly irradiated cells to be just 0.04% of the total cells on the dish using the highly controlled microbeam irradiation system. The percent survival in the cells with wild-type P53 was around 90%, while almost 100% was observed in the cells with mutated-type P53. The results are consistent with the data using the carbon-ion broad beams with the shielding method at HIMAC. Our overall results showed that bystander cell-killing effect was observed in the cells with wild-type P53, but not in the P53-mutated cells. There is clear evidence that the spot scanning irradiation system of carbon ions enables the enhanced cell killing in cells with wild-type P53 gene via gap-junction mediated bystander effect.

Oral presentation

Epigenetic modification potentially sensitizes heavy-ion therapy for malignancy

Saito, Katsuyo*; Funayama, Tomoo; Kobayashi, Yasuhiko; Murakami, Takashi*

no journal, , 

Malignant melanoma is one of the most common cutaneous malignancies. Epigenetic modifiers, such as histone deacetylase inhibitors (HDACi) and DNA methyltransferase inhibitors, have emerged recently as promising anticancer agents and has been expected as a sensitizer for other cancer therapeutics including radiotherapy. In addition, the biological effects of the high linear energy transfer (LET) heavy-ion radiation are more pronounced than the low-LET radiation. These accumulating evidences allowed us to investigate whether the use of HDACi could sensitize melanoma cells for the heavy-ion therapy. Treatment of B16F10 melanoma cells with HDACi in combination with heavy-ion radiation provided enhanced anti-tumor effects. These data suggest that combination of HDACi together with heavy-ion therapy may provide improved therapeutic responses in melanoma patients.

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