The read-out system of spatial distribution of thermoluminescence in meteorites

The thermoluminescence (TL) technique used for dating the terrestrial age of meteorites is based on the TL fading of interior samples. The depth dependence of the TL for Antarctic meteorites with fusion crust is measured. Usually, meteorites are powdered and their TL measured under a photomultiplier. In this case, a TL spatial distribution of a cross section of antarctic meteorites is measured using a read out system of spatial distribution of TL, since a meteorite is made up of inhomogeneous material. Antarctic meteorites MET-78028(L6) and ALH-77278(L13) are used

Effects of annealing time on structural and magnetic properties of L10-FePt nanoparticles synthesized by the SiO2-nanoreactor method

We investigated effects of annealing time on structural and magnetic properties of the L10-FePt nanoparticles synthesized by the SiO2-nanoreacter method. The magnetization and powder X-ray diffraction studies revealed that the annealing at 900 oC for 9 hr could convert all of the fcc-nanoparticles to the well-crystallized L10 structure with a large coercivity while keeping their particle size. Such monodisperse and highly crystalline L10-FePt nanoparticles are a promising material for the realization of ultra-high density recording.Comment: 9 pages, 2 figure

Differential distribution of microtubules in immature osteocytes in vivo

Objectives: The transition from osteoblasts to osteocytes is associated with dramatic changes in the cytoskeleton. We previously showed that the formation of osteoblast cell processes in 3D culture is microtubule dependent. However, the distribution of microtubules during the transition from osteoblasts to osteocytes in vivo is unknown. In this study, we investigated the distribution of microtubules in osteocytes in vivo. Methods: We observed the microtubules in osteocytes in chick embryonic calvaria via fluorescence staining of microtubules and confocal laser scanning microscopy. Results: Microtubules were observed throughout the cytoplasm in all examined osteoblasts. In immature osteocytes, several cell processes contained microtubules, whereas in mature osteocytes, microtubules were localized only in the cell body. Conclusion: These results suggest that the early arrangement of microtubules may be correlated with the initial development of osteocyte processes. (C) 2018 Japanese Association for Oral Biology. Published by Elsevier B.V. All rights reserved.Peer reviewe

Experimental exploration of ErB2_2 and SHAP analysis on a machine-learned model of magnetocaloric materials for materials design

Stimulated by a recent report of a giant magnetocaloric effect in HoB$_2$ found via machine-learning predictions, we have explored the magnetocaloric properties of a related compound ErB$_2$, that has remained the last ferromagnetic material among the rare-earth diboride (REB$_2$) family with unreported magnetic entropy change |{\Delta}SM|. The evaluated $|\Delta S_M|$ at field change of 5 T in ErB$_2$ turned out to be as high as 26.1 (J kg$^{-1}$ K$^{-1}$) around the ferromagnetic transition (${T_C}$) of 14 K. In this series, HoB$_2$ is found to be the material with the largest $|\Delta S_M|$ as the model predicted, while the predicted values showed a deviation with a systematic error compared to the experimental values. Through a coalition analysis using SHAP, we explore how this rare-earth dependence and the deviation in the prediction are deduced in the model. We further discuss how SHAP analysis can be useful in clarifying favorable combinations of constituent atoms through the machine-learned model with compositional descriptors. This analysis helps us to perform materials design with aid of machine learning of materials data.Comment: 9 pages, 10 figures. Accepted manuscript. Published by Taylor & Francis in STAM:Methods, available at https://doi.org/10.1080/27660400.2023.221747

Growth Dynamics of Photoinduced Domains in Two-Dimensional Charge-Ordered Conductors Depending on Stabilization Mechanisms

Photoinduced melting of horizontal-stripe charge orders in quasi-two-dimensional organic conductors \theta-(BEDT-TTF)2RbZn(SCN)4[BEDT-TTF=bis(ethylenedithio)tetrathiafulvalene] and \alpha-(BEDT-TTF)2I3 is investigated theoretically. By numerically solving the time-dependent Schr\"odinger equation, we study the photoinduced dynamics in extended Peierls-Hubbard models on anisotropic triangular lattices within the Hartree-Fock approximation. The melting of the charge order needs more energy for \theta-(BEDT-TTF)2RbZn(SCN)4 than for \alpha-(BEDT-TTF)2I3, which is a consequence of the larger stabilization energy in \theta-(BEDT-TTF)2RbZn(SCN)4. After local photoexcitation in the charge ordered states, the growth of a photoinduced domain shows anisotropy. In \theta-(BEDT-TTF)2RbZn(SCN)4, the domain hardly expands to the direction perpendicular to the horizontal-stripes. This is because all the molecules on the hole-rich stripe are rotated in one direction and those on the hole-poor stripe in the other direction. They modulate horizontally connected transfer integrals homogeneously, stabilizing the charge order stripe by stripe. In \alpha-(BEDT-TTF)2I3, lattice distortions locally stabilize the charge order so that it is easily weakened by local photoexcitation. The photoinduced domain indeed expands in the plane. These results are consistent with recent observation by femtosecond reflection spectroscopy.Comment: 9 pages, 8 figures, to appear in J. Phys. Soc. Jpn. Vol. 79 (2010) No.

Neural networks for a quick access to a digital twin of scanning physical properties measurements

For performing successful measurements within limited experimental time, efficient use of preliminary data plays a crucial role. This work shows that a simple feedforward type neural networks approach for learning preliminary experimental data can provide quick access to simulate the experiment within the learned range. The approach is especially beneficial for physical properties measurements with scanning on multiple axes, where derivative or integration of data are required to obtain the objective quantity. Due to its simplicity, the learning process is fast enough for the users to perform learning and simulation on-the-fly by using a combination of open-source optimization techniques and deep-learning libraries. Here such a tool for augmenting the experimental data is proposed, aiming to help researchers to decide the most suitable experimental conditions before performing costly experiments in real. Furthermore, this tool can also be used from the perspective of taking advantage of reutilizing and repurposing previously published data, accelerating data-driven exploration of functional materials.Comment: 19 pages, 5 figures + 7 pages of Supporting Informatio

Charge Order with Structural Distortion in Organic Conductors: Comparison between \theta-(ET)2RbZn(SCN)4 and \alpha-(ET)2I3

Charge ordering with structural distortion in quasi-two-dimensional organic conductors \theta-(ET)2RbZn(SCN)4 (ET=BEDT-TTF) and \alpha-(ET)2I3 is investigated theoretically. By using the Hartree-Fock approximation for an extended Hubbard model which includes both on-site and intersite Coulomb interactions together with Peierls-type electron-lattice couplings, we examine the role of lattice degrees of freedom on charge order. It is found that the experimentally observed, horizontal charge order is stabilized by lattice distortion in both compounds. In particular, the lattice effect is crucial to the realization of the charge order in \theta-(ET)2RbZn(SCN)4, while the peculiar band structure whose symmetry is lower than that of \theta-(ET)2RbZn(SCN)4 in the metallic phase is also an important factor in \alpha-(ET)2I3 together with the lattice distortion. For \alpha-(ET)2I3, we obtain a phase transition from a charge-disproportionated metallic phase to the horizontal charge order with lattice modulations, which is consistent with the latest X-ray experimental result.Comment: 10 pages, 13 figures, to appear in J. Phys. Soc. Jpn. Vol. 77 (2008) No.

Combination of Ferromagnetic and Antiferromagnetic Features in Heisenberg Ferrimagnets

We investigate the thermodynamic properties of Heisenberg ferrimagnetic mixed-spin chains both numerically and analytically with particular emphasis on the combination of ferromagnetic and antiferromagnetic features. Employing a new density-matrix renormalization-group technique as well as a quantum Monte Carlo method, we reveal the overall thermal behavior: At very low temperatures, the specific heat and the magnetic susceptibility times temperature behave like $T^{1/2}$ and $T^{-1}$, respectively, whereas at intermediate temperatures, they exhibit a Schottky-like peak and a minimum, respectively. Developing the modified spin-wave theory, we complement the numerical findings and give a precise estimate of the low-temperature behavior.Comment: 9 pages, 9 postscript figures, RevTe