Colossal barocaloric effects in plastic crystals

Li, B.*; Kawakita, Yukinobu; Kawamura, Seiko; Sugahara, Takeshi*; Wang, H.*; Wang, J.*; Chen, Y.*; Kawaguchi, Saori*; Kawaguchi, Shogo*; Ohara, Koji*; et al.

Nature, 567(7749), p.506 - 510, 2019/03

https://doi.org/10.1038/s41586-019-1042-5

Refrigeration is of vital importance for modern society for example, for food storage and air conditioning- and 25 to 30% of the world's electricity is consumed for refrigeration. Current refrigeration technology mostly involves the conventional vapour compression cycle, but the materials used in this technology are of growing environmental concern because of their large global warming potential. As a promising alternative, refrigeration technologies based on solid-state caloric effects have been attracting attention in recent decades. However, their application is restricted by the limited performance of current caloric materials, owing to small isothermal entropy changes and large driving magnetic fields. Here we report colossal barocaloric effects (CBCEs) (barocaloric effects are cooling effects of pressure-induced phase transitions) in a class of disordered solids called plastic crystals. The obtained entropy changes in a representative plastic crystal, neopentylglycol, are about 389 joules per kilogram per kelvin near room temperature. Pressure-dependent neutron scattering measurements reveal that CBCEs in plastic crystals can be attributed to the combination of extensive molecular orientational disorder, giant compressibility and highly anharmonic lattice dynamics of these materials. Our study establishes the microscopic mechanism of CBCEs in plastic crystals and paves the way to next-generation solid-state refrigeration technologies.

Development of optical fiber detector for measurement of fast neutron

Yagi, Takahiro*; Misawa, Tsuyoshi*; Pyeon, C. H.*; Unesaki, Hironobu*; Shiroya, Seiji*; Kawaguchi, Shinichi*; Okajima, Shigeaki; Tani, Kazuhiro*

Proceedings of International Conference on the Physics of Reactors, Nuclear Power; A Sustainable Resource (PHYSOR 2008) (CD-ROM), 8 Pages, 2008/09

In order to insert a neutron detector in a narrow space such as a gap of between fuel plates and measure the fast neutrons in real time, a neutron detector with an optical fiber has been developed. This detector consists of an optical fiber whose tip is covered with mixture of neutron converter material and scintillator such as ZnS(Ag). The detector for fast neutrons uses ThO as converter material because Th makes fission reaction with fast neutrons. The place where Th can be uses is limited by regulations because Th is nuclear fuel material. The purpose of this research is to develop a new optical fiber detector to measure fast neutrons without Th and to investigate the characteristic of the detector. These detectors were used to measure a D-T neutron generator and fast neutron flux distribution at Fast Critical Assembly. The results showed that the fast neutron flux distribution of the new optical fiber detector with ZnS(Ag) was the same as it of the activation method, and the detector are effective for measurement of fast neutrons.

Radiation effects of the boron nano-belt on the electronic conductivity

Kirihara, Kazuhiro*; Kawaguchi, Kenji*; Shimizu, Yoshiki*; Sasaki, Takeshi*; Koshizaki, Naoto*; Kimura, Kaoru*; Yamada, Yoichi; Yamamoto, Hiroyuki; Shamoto, Shinichi

no journal, , 

Radiation effects of the boron nano-belt on the electronic conductivity have been studied.

Effect of neutron irradiation on the electrical transport of boron nanobelt devices

Kirihara, Kazuhiro*; Kawaguchi, Kenji*; Shimizu, Yoshiki*; Sasaki, Takeshi*; Koshizaki, Naoto*; Kimura, Kaoru*; Yamada, Yoichi; Yamamoto, Hiroyuki; Shamoto, Shinichi

no journal, , 

Isotopic B atom has large thermal neutron capture cross section. Li atom and particle as a product of the neutron reaction can change the electrical transport property of the boron-rich semiconductor because they provide carrier doping and lattice defects. We successfully synthesized catalyst-free single-crystalline boron nanobelts (BNBs) and clarified the electrical transport and photoconduction mechanism of individual nanobelt. The BNB device is promising candidates for solid-state neutron sensors with both high resolution and good discrimination performance between neutron and -ray. In the presentation, we discuss the performance of thermal neutron detection of BNB devices. Isotopic B enriched BNBs was synthesized to detect thermal neutrons efficiently. Electrical conductance of a nanobelt increased to eight times after the thermal neutron irradiation with a dose of 1.810 cm by the neutron reaction of B.

Space exposure experiments of microorganisms as a part of TANPOPO; Astrobiology exposure and micrometeoroid capture experiments

Yokobori, Shinichi*; Yang, Y.*; Fujisaki, Kenta*; Kawaguchi, Yuko*; Hashimoto, Hirofumi*; Yamashita, Masamichi*; Yano, Hajime*; Okudaira, Kyoko*; Yoshimura, Yoshitaka*; Narumi, Issei; et al.

no journal, , 

no abstracts in English

Quest for microorganisms existing at high atmosphere and space

Yokobori, Shinichi*; Yang, Y.*; Sugino, Tomohiro*; Kawaguchi, Yuko*; Itahashi, Shiho*; Fujisaki, Kenta*; Fushimi, Hidehiko*; Hasegawa, Sunao*; Hashimoto, Hirofumi*; Hayashi, Nobuhiro*; et al.

no journal, , 

Microbes capture and expose experiments on ISS proposed in Tanpopo mission

Kawaguchi, Yuko*; Sugino, Tomohiro*; Yang, Y.*; Takahashi, Yuta*; Yoshimura, Yoshitaka*; Tsuji, Takashi*; Kobayashi, Kensei*; Tabata, Makoto*; Hashimoto, Hirofumi*; Narumi, Issei; et al.

no journal, , 

no abstracts in English

The Microbe capture experiment in space; Fluorescence microscopic detection of microbes captured by aerogel

Sugino, Tomohiro*; Yokobori, Shinichi*; Yang, Y.*; Kawaguchi, Yuko*; Hasegawa, Sunao*; Hashimoto, Hirofumi*; Imai, Eiichi*; Okudaira, Kyoko*; Kawai, Hideyuki*; Tabata, Makoto*; et al.

no journal, , 

Capture and space exposure experiments of microorganisms on the ISS orbit proposed in "TANPOPO" mission

Yokobori, Shinichi*; Yang, Y.*; Kawaguchi, Yuko*; Sugino, Tomohiro*; Takahashi, Yuta*; Narumi, Issei; Nakagawa, Kazumichi*; Tabata, Makoto*; Kobayashi, Kensei*; Marumo, Katsumi*; et al.

no journal, , 

Resistance of sp. to environmental factors of International Space Station (ISS) orbit; Microbes exposure experiment at ISS in the mission "Tanpopo"

Kawaguchi, Yuko*; Yang, Y.*; Kawashiri, Narutoshi*; Shiraishi, Keisuke*; Shimizu, Yasuyuki*; Sugino, Tomohiro*; Takahashi, Yuta*; Tanigawa, Yoshiaki*; Narumi, Issei; Sato, Katsuya; et al.

no journal, ,