Aoyama Gakuin University

About: Aoyama Gakuin University is a education organization based out in Tokyo, Japan. It is known for research contribution in the topics: Superconductivity & Thin film. The organization has 3494 authors who have published 6419 publications receiving 115648 citations. The organization is also known as: Aoyama gakuin daigaku.

Lead isotope ratios in Tokyo Bay sediments and their implications in the lead consumption of Japanese industries.

Abstract: The annual lead accumulation and the change of the isotope ratios of sediments in the Tokyo Bay are discussed in relation to the development of the Japanese industrial activities. Lead has been spread out from the north western part of the bay, showing a part of concentric circles. The total lead accumulation rate in the bay was calculated to be 17 t/y in 1880, which was regarded as the non-artificial lead input rate, and increased gradually with time reflecting increase in the consumption of lead in Japanese industries. In 1920, the isotope ratios changed extraordinarily, which was estimated to be caused by the introduction of the Broken Hill lead of Australia. The annual lead accumulation has been accelerated since 1950 and the isotope ratios have also been affected by the change in the varieties of the sources. It reached a maximum, 110t/y, in 1970 and was reduced to 71 t/y in 1980. Although the sources of anthropogenic lead are complicated, the gasoline additives would be one of the major sources for the lead pollution until 1970. Although the consumption of gasoline additives in 1980 was reduced to 1/20 of the 1970 value in Japan, the decrease of the gasoline lead seems not yet clearly observed isotopically in the sediments of the bay. The lead in the cored sediments was confirmed not to have moved vertically, but showed a systematic difference horizontally after anthropogenic lead was introduced in the bay. The systematic difference of the isotope ratios in the surface sediments indicates the difference of the pollution sources.

A Thousand Days After the Merger: Continued X-Ray Emission From gw170817

Abstract: Recent observations with the Chandra X-ray telescope continue to detect X-ray emission from the transient GW170817. In a total exposure of 96.6 ks, performed between March 9 and March 16 2020 (935 d to 942 d after the merger), a total of 8 photons are measured at the source position, corresponding to a significance of about 5 sigma. Radio monitoring with the Australian Telescope Compact Array (ATCA) shows instead that the source has faded below our detection threshold (<33 uJy, 3 sigma). By assuming a constant spectral index beta=0.585, we derive an unabsorbed X-ray flux of approximately 1.4E-15 erg/cm^2/s, higher than earlier predictions, yet still consistent with a simple structured jet model. We discuss possible scenarios that could account for prolonged emission in X-rays. The current dataset appears consistent both with energy injection by a long-lived central engine and with the onset of a kilonova afterglow, arising from the interaction of the sub-relativistic merger ejecta with the surrounding medium. Long-term monitoring of this source will be essential to test these different models.

Extended Slow-Roll Conditions and Rapid-Roll Conditions

Abstract: We derive slow-roll conditions for a scalar field which is non-minimally coupled with gravity in a consistent manner and express spectral indices of scalar/tensor perturbations in terms of the slow-roll parameters. The conformal invariance of the curvature perturbation is proved without linear approximations. Rapid-roll conditions are also derived, and the relation with the slow-roll conditions is discussed.

Control of the Single‐Molecule Magnet Behavior of Lanthanide‐Diarylethene Photochromic Assemblies by Irradiation with Light

Abstract: Lanthanide-based extended coordination frameworks showing photocontrolled single-molecule magnet (SMM) behavior were prepared by combining highly anisotropic Dy(III) and Ho(III) ions with the carboxylato-functionalized photochromic molecule 1,2-bis(5-carboxyl-2-methyl-3-thienyl)perfluorocyclopentene (H2 dae), which acts as a bridging ligand. As a result, two new compounds of the general formula [{Ln(III) 2 (dae)3 (DMSO)3 (MeOH)}⋅10 MeOH]n (M=Dy for 1 a and Ho for 2) and two additional pseudo-polymorphs [{Dy(III) 2 (dae)3 (DMSO)3 (H2 O)}⋅x MeOH]n (1 b) and [{Dy(III) 2 (dae)3 (DMSO)3 (DMSO)}⋅x MeOH]n (1 c) were obtained. All four compounds have 2D coordination-layer topologies, in which carboxylate-bridged Ln2 units are linked together by dae(2-) anions into grid-like frameworks. All four compounds exhibited a strong reversible photochromic response to UV/Vis light. Moreover, both 1 a and 2 show field-induced SMM behavior. The slow magnetic relaxation of 1 a is influenced by the photoisomerization reaction leading to the observation of the cross-effect: photocontrolled SMM behavior.