On the Magnetic and Electric Properties of (Fe_<1-x>Co_x)_<0.89>Cr_<0.11> Alloys

To make clear the mechanism of the appearance of large spontaneous volume magnetostriction of fcc (Fe_Co_x)_Cr_ alloys, their magnetization and elctrical resistivity were measured and the following results were obtained : (1) The dependences of the mean magnetic moments and the Curie point on the concentration, x, and the outer electron concentration, n, of the alloys were similar to those in the Fe-Ni and Fe-Pd Invar alloy systems. That is, the alloys in these three systems are ferromagnetic on the Co- and Ni-rich sides and their ferromagnetic moments disappeared at the n of about 8.2～8.4 which corresponds to the concentration containing Fe more than it in Invar alloys. (2) The magnetization-temperature curve of the Invar alloys mentioned above did not follow Brillouin\u27s function. (3) The electrical resistivity-temperature curves of the Invar alloys showed an anomalous broad maximum near the Curie point. And the residual resistivity were very large. These phenomena may be explained by the co-existence of the ferromagnetic and antiferromagnetic states. It may be considered that the co-exsistence of the two magnetic states is closely connected with the sharp drop of the ferromagnetic moments near the concentration of Invar type alloys

Magnetic Properties of h.c.p. Fe-Ru Alloys

X-ray diffraction experiments at room temperature and magnetization measurements from 4.2 to about 1000°K have been performed on the whole composition range of Fe-Ru alloys. The magnetic susceptibility, χ, in the ε phase of 100 at% Ru to 13 at% Ru-Fe alloy shows a Pauli-paramagnetic temperature dependence at high temperatures with small negative and positive temperature coefficients for the alloys less than and more than 30 at% Ru, respectively. The value of χ at room temperature increases with increasing Fe concentration from 100 at% Ru ; the extrapolated value of χ, that is χ of the ε Fe, is as large as 10^/Oe/mole. The Fe-rich alloys in the ε phase shows some decrease in χ at low temperatures, suggesting the occurrence of metallic antiferromagnetic ordering. The reason for the variation in χ with Fe concentration may be attributed to the change in the density of states at the Fermi level due to the change of the width of the d-band, relative position of the Fermi level being unchanged because of the fixed number of outer electrons

Magnetic Domain Structure of an Amorphous Fe-P-C Alloy

The domain structure of an amorphous Fe_P_C_7 alloy ribbon produced by the centrifugal solidification technique was investigated using the magnetic powder pattern technique. Two different types of domains (a maze domain and a 180°-domain) were observed on the specimen surface. The relationship between the domain structure and the magnetization process was also investigated. The results showed that some of the 180°-walls, which ran nearly parallel to the long axis of the ribbon, caused the hysteresis in the magnetization curve, while the maze domain was responsible for the difficulty in obtaining the saturation in magnetization. The maze domain arises probably from the uniaxial magnetic anisotropy having the direction of easy magnetization perpendicular to the surface. This anisotropy seems to be caused by the magnetoelastic coupling between positive magnetostriction and internal stress in the specimen

Electronic Structure and Electron Correlation in LaFeAsO_{1-x}F_x and LaFePO_{1-x}F_x

Photoemission spectroscopy is used to investigate the electronic structure of the newly discovered iron-based superconductors LaFeAsO_{1-x}F_x and LaFePO_{1-x}F_x. Line shapes of the Fe 2p core-level spectra suggest an itinerant character of Fe 3d electrons. The valence-band spectra are generally consistent with band-structure calculations except for the shifts of Fe 3d-derived peaks toward the Fermi level. From spectra taken in the Fe 3p -> 3d core-absorption region, we have obtained the experimental Fe 3d partial density of states, and explained it in terms of a band-structure calculation with a phenomenological self-energy correction, yielding a mass renormalization factor of ~< 2.Comment: 4 pages, 5 figure

Spontaneous Volume Magnetostriction of (Fe_<1-x>Co_x)_<0.89> Cr_<0.11> Alloys

To make clear the origin of the Invar property, some physical properties of fcc (Fe_Co_x)_Cr_ alloys which are most typicall Invar alloys in the Fe-Co-Cr system (Stainless Invar) have been studied so far. In the present experiment, the temperature and composition dependences of thermal expansion for the alloys were measured and the following results were obtained : It has been ascertained that these alloys have the same remarkable Invar characteristics as reported by Masumoto. Thermal expansions measurements at sufficiently high temperatures made it clear that the Invar property is caused by the effect of the spontaneous volume magnetostriction in the temperature range below the Curie point of short-range magnetic ordering. And the spontaneous volume magnetostriction at 0°K has been estimated from the normal thermal expansion curves (only lattice vibration), compared with thermal expansion of Ni. The value obtained on an alloy of x=0.6 was 12±1×10^, about three times greater than that for Fe-Ni Invar alloys. The microscopic mechanism or the cause of this large spontaneous volume magnetostriction may be ascribed to (1) the magnetic mechansim due to the characteristic electronic state of Invar alloys and (2) the elastic mechanism due to peculiar lattice properties of Invar alloys associated with the α⇌γ martensitic transformation process which is common in each system having the Invar region

How many hot days and heavy precipitation days will grandchildren experience that break the records set in their grandparents’ lives?

孫は祖父母が遭遇しないような暑い日と大雨を何度経験するのか? --極端な気象現象の変化に関する世代間不公平性とその地域間不公平性の評価--. 京都大学プレスリリース. 2021-06-14.One of the major barriers to climate communication is that climate change is often presented to the public in such a way that impacts seem distant in time. To improve how climate change resonates with people, we propose a simple indicator: how many extreme events (hot days and heavy precipitation days) are grandchildren projected to experience that their grandparents will not experience in their lives? We analyse the Coupled Model Intercomparison Project Phase 6 ensemble. During grandchildren's lifetime (2020–2100) under the shared socioeconomic pathway 5–8.5 (SSP5-8.5), in some tropical regions, they are projected to experience >1000 hot days and >5 heavy precipitation days breaking records set in their grandparents' lifetime until 2040. These numbers of unprecedented hot days and heavy precipitation days under SSP5-8.5 are greater in countries with lower CO₂ emissions and income per capita than in countries with higher CO₂ emissions and income per capita. We show that not only the numbers of unprecedented hot days and heavy precipitation days but also their unevenness across countries can be significantly lowered in the SSP1-2.6 scenario, which is consistent with the 2 °C goal of the Paris Agreement. This new approach would help adults easily understand how their climate change mitigation efforts could decrease the unprecedented extreme events during youths' lifetime and reduce the intergenerational and intragenerational inequalities regarding extreme events

Angle-resolved photoemission study of MX-chain compound [Ni(chxn)2_2Br]Br2_2

We report on the results of angle-resolved photoemission experiments on a quasi-one-dimensional $MX$-chain compound [Ni(chxn)$_2$Br]Br$_2$ (chxn = 1$R$,2$R$-cyclohexanediamine), a one-dimensional Heisenberg system with $S=1/2$ and $J \sim 3600$ K, which shows a gigantic non-linear optical effect. A "band" having about 500 meV energy dispersion is found in the first half of the Brillouin zone $(0\le kb/\pi <1/2)$, but disappears at $kb / \pi \sim 1/2$. Two dispersive features, expected from the spin-charge separation, as have been observed in other quasi-one-dimensional systems like Sr$_2$CuO$_3$, are not detected. These characteristic features are well reproduced by the $d$-$p$ chain model calculations with a small charge-transfer energy $\Delta$ compared with that of one-dimensional Cu-O based compounds. We propose that this smaller $\Delta$ is the origin of the absence of clear spin- and charge-separation in the photoemission spectra and strong non-linear optical effect in [Ni(chxn)$_2$Br]Br$_2$.Comment: 4 pages, 3 figure

Behavior of vascular resistance undergoing various pressure insufflation and perfusion on decellularized lungs

Bioengineering of functional lung tissue by using whole lung scaffolds has been proposed as a potential alternative for patients awaiting lung transplant. Previous studies have demonstrated that vascular resistance (Rv) could be altered to optimize the process of obtaining suitable lung scaffolds. Therefore, this work was aimed at determining how lung inflation (tracheal pressure) and perfusion (pulmonary arterial pressure) affect vascular resistance. This study was carried out using the lungs excised from 5 healthy male Sprague-Dawley rats. The trachea was cannulated and connected to a continuous positive airway pressure (CPAP) device to provide a tracheal pressure ranging from 0 to 15 cmH(2)O. The pulmonary artery was cannulated and connected to a controlled perfusion system with continuous pressure (gravimetric level) ranging from 5 to 30 cmH(2)O. Effective Rv was calculated by ratio of pulmonary artery pressure (P-PA) by pulmonary artery flow (V'(PA)). Rv in the decellularized lungs scaffolds decreased at increasing V'(PA), stabilizing at a pulmonary arterial pressure greater than 20 cmH(2)O. On the other hand, CPAP had no influence on vascular resistance in the lung scaffolds after being subjected to pulmonary artery pressure of 5 cmH(2)O. In conclusion, compared to positive airway pressure, arterial lung pressure markedly influences the mechanics of vascular resistance in decellularized lungs. (C) 2016 Elsevier Ltd. All rights reserved