Tohoku University

About: Tohoku University is a education organization based out in Sendai, Japan. It is known for research contribution in the topics: Magnetization & Alloy. The organization has 72116 authors who have published 170791 publications receiving 3941714 citations. The organization is also known as: Tōhoku daigaku.

Hydrothermal Synthesis of Metal Oxide Fine Particles at Supercritical Conditions

Abstract: Supercritical water can provide an excellent reaction environment for hydrothermal crystallization of metal oxide particles. Because of the drastic change of properties of water around the critical point, density, dielectric constant, and ionic product, the phase behavior for the supercritical water-light gas (O 2 , H 2 , etc) system and reaction equilibrium/rate can be varied to synthesize new materials or define particle morphologies. In this work, hydrothermal crystallization experiments were performed with several types of flow apparatuses that allow convenient manipulation of variables such as temperature, pressure, and residence time. The proposed supercritical hydrothermal synthesis method has the following desirable features: (1) ultrafine particles can be produced, (2) morphology of the produced particles can be controlled with small changes in pressure or temperature, and (3) a reducing or oxidizing atmosphere can be applied by introducing oxygen, hydrogen, or other gases. An overview of this method is given for functional material synthesis of significant industrial interest including barium hexaferrite magnetic particles, YAG/Tb phosphor fine particles, and lithium cobalt fine crystals.

Touchdown of the Hayabusa spacecraft at the Muses Sea on Itokawa.

Abstract: After global observations of asteroid 25143 Itokawa by the Hayabusa spacecraft, we selected the smooth terrain of the Muses Sea for two touchdowns carried out on 19 and 25 November 2005 UTC for the first asteroid sample collection with an impact sampling mechanism. Here, we report initial findings about geological features, surface condition, regolith grain size, compositional variation, and constraints on the physical properties of this site by using both scientific and housekeeping data during the descent sequence of the first touchdown. Close-up images revealed the first touchdown site as a regolith field densely filled with size-sorted, millimeter- to centimeter-sized grains.

DNA Damage-Dependent Acetylation and Ubiquitination of H2AX Enhances Chromatin Dynamics

Abstract: Chromatin reorganization plays an important role in DNA repair, apoptosis, and cell cycle checkpoints. Among proteins involved in chromatin reorganization, TIP60 histone acetyltransferase has been shown to play a role in DNA repair and apoptosis. However, how TIP60 regulates chromatin reorganization in the response of human cells to DNA damage is largely unknown. Here, we show that ionizing irradiation induces TIP60 acetylation of histone H2AX, a variant form of H2A known to be phosphorylated following DNA damage. Furthermore, TIP60 regulates the ubiquitination of H2AX via the ubiquitin-conjugating enzyme UBC13, which is induced by DNA damage. This ubiquitination of H2AX requires its prior acetylation. We also demonstrate that acetylation-dependent ubiquitination by the TIP60-UBC13 complex leads to the release of H2AX from damaged chromatin. We conclude that the sequential acetylation and ubiquitination of H2AX by TIP60-UBC13 promote enhanced histone dynamics, which in turn stimulate a DNA damage response.