Japan Atomic Energy Agency

About: Japan Atomic Energy Agency is a government organization based out in Tōkai-mura, Japan. It is known for research contribution in the topics: Neutron & Laser. The organization has 7151 authors who have published 17791 publications receiving 259118 citations. The organization is also known as: JAEA & Nihon genshiryoku kenkyū kaihatsu kikō.

Efficient selenium(IV) detection and removal from water by tailor-made novel conjugate adsorbent

Abstract: Selenium occurs naturally in the environment and is toxic at elevated concentrations, which has been a challenging issue for environmental scientists. This work was devoted to the detection and removal the selenium (Se(IV)) from aqueous solutions using organic ligand an immobilized conjugate adsorbent. The organic ligand of (3-(3-(methoxycarbonyl) benzylidene)hydrazinyl) benzoic acid was synthesized and indirectly immobilized onto the mesoporous silica. The adsorbent was applied to detect and remove Se(IV) in aqueous solutions at optimum conditions. This adsorbent exhibited high surface area-to-volume ratios and pores were uniform nanostructures. The adsorbent permitted rapid Se(IV) capturing detectable by naked eye observation. The limit of detection was 2.02 μg/L by the proposed method of the conjugate adsorbent. The Se(IV) capture system was optimized by varying the parameters of contact time, pH, initial concentration, competing ions and elution operations. The pH effect played an important role and the solution pH ranging from 0.5 to 7.0 was investigated. The data confirmed that acidic pH enhanced the Se(IV) sorption on the conjugate adsorbent resulting in an increased sorption efficiency percentage of Se(IV) to >98% at pH 1.50. The data were also fitted to the Langmuir isotherm, and the maximum sorption capacity was 93.56 mg/g. The introduction of diverse ions was individually added to solution, and these had no significant effect on the Se(IV) sorption by the adsorbent. The 0.20 M NaOH was used an eluent in the elution operation, and the adsorbent was used in many cycles without loss of cage cavities. Therefore, the conjugate adsorbent has shown favorable capturing ability in water samples, and this could be used as efficient adsorbents in potential practical applications for Se(IV) detection and removal from wastewater.

Colossal barocaloric effects in plastic crystals

Abstract: Refrigeration is of vital importance for modern society—for example, for food storage and air conditioning—and 25 to 30 per cent of the world’s electricity is consumed for refrigeration1. 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 potential2. As a promising alternative, refrigeration technologies based on solid-state caloric effects have been attracting attention in recent decades3–5. 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. Colossal barocaloric effects are observed in the plastic crystal neopentylglycol and found to originate from the extensive molecular orientational disorder, giant compressibility and highly anharmonic lattice dynamics of the material.

Emergence of a complete heavy-quark spin symmetry multiplet: seven molecular pentaquarks in light of the latest LHCb analysis

Abstract: A recent analysis by the LHCb Collaboration suggests the existence of three narrow pentaquarklike states—the Pc(4312), Pc(4440), and Pc(4457)—instead of just one in the previous analysis [the Pc(4450)]. The closeness of the Pc(4312) to the D¯Σc threshold and the Pc(4440) and Pc(4457) to the D¯*Σc threshold suggests a molecular interpretation of these resonances. We show that these three pentaquarklike resonances can be naturally accommodated in a contact-range effective field theory description that incorporates heavy-quark spin symmetry. This description leads to the prediction of all the seven possible S-wave heavy antimeson-baryon molecules [that is, there should be four additional molecular pentaquarks in addition to the Pc(4312), Pc(4440), and Pc(4457)], providing the first example of a heavy-quark spin symmetry molecular multiplet that is complete. If this is confirmed, it will not only give us an impressive example of the application of heavy-quark symmetries and effective field theories in hadron physics, it will also uncover a clear and powerful ordering principle for the molecular spectrum, reminiscent of the SU(3)-flavor multiplets to which the light hadron spectrum conforms.

The reaction 48Ca + 238U → 286112* studied at the GSI-SHIP

Abstract: The synthesis of element 116 in fusion-evaporation reactions of a 48Ca beam with radioactive 248Cm targets was studied at the velocity filter SHIP of GSI in Darmstadt. At excitation energies of the compound nuclei of 40.9MeV, four decay chains were measured, which were assigned to the isotope 292116, and one chain, which was assigned to 293116. Measured cross-sections of (3.4−1.6+2.7) pb and (0.9−0.7+2.1), respectively, and decay data of the chains agree with data measured previously at the Flerov Laboratory of Nuclear Reactions in Dubna. As a new result, one α-decay chain was measured, which terminates after four α decays by spontaneous fission. The α energies of the second-to-fourth decay are considerably higher than those measured for the α decays of 289114, 285Cn, and 281Ds and the spontaneous fission half-life is significantly longer than that of 277Hs measured in previous experiments. A possible assignment is discussed in the frame of excited quasiparticle states of nuclei populated in the decay chain from 293116. Also other possible assignments were considered and are discussed. At an excitation energy of 45.0MeV no events were observed resulting in a one-event cross-section limit of 1.6 pb. The technical aspects related with the use of radioactive target material at SHIP are described in detail. The experience gained in this experiment will serve as a basis for future experiments aiming to study still heavier elements at the velocity filter SHIP.