Tohoku University

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

Glass-forming ability of alloys

Abstract: New amorphous alloys exhibiting a wide supercooled liquid region before crystallization were found to form by melt spinning in wide composition ranges of LaAlM, MgYM and ZrAlM (M = Ni or Cu) systems consisting of the constituent elements with significantly different atomic sizes. The temperature span between glass transition temperature, Tg, and crystallization temperature, Tx, ΔTx ( = Tx − Tg) is > 50 K in the compositional ranges around La2AlM, Mg6Ln3M and Zr3AlM and the largest ΔTx reaches 126 K. The critical cooling rate for the glass formation, Rc, is as low as 87–115 K/s and Tg/Tm is > 0.6 in the composition range where ΔTx > 50 K. There is a clear tendency for Rc to decrease with an increase of ΔTx and Tg/Tm. The crystallization of the alloys with large ΔTx occurs through the simultaneous precipitation of several compounds. Based on these results, it is presumed that the large glass-forming ability for these alloys is due to a combined effect of the difficulty of long-range atomic redistribution required for the precipitation of the compounds, the rapid increase of viscosity with decreasing temperature and the large liquidus-solidus interfacial energy which originates from the optimally bonding and packing states resulting from large negative heat of mixing and large atomic size ratios.

The Antioxidant Defense System Keap1-Nrf2 Comprises a Multiple Sensing Mechanism for Responding to a Wide Range of Chemical Compounds

Abstract: Animals have evolved defense systems for surviving in a chemically diverse environment. Such systems should demonstrate plasticity, such as adaptive immunity, enabling a response to even unknown chemicals. The antioxidant transcription factor Nrf2 is activated in response to various electrophiles and induces cytoprotective enzymes that detoxify them. We report here the discovery of a multiple sensing mechanism for Nrf2 activation using zebrafish and 11 Nrf2-activating compounds. First, we showed that six of the compounds tested specifically target Cys-151 in Keap1, the ubiquitin ligase for Nrf2, while two compounds target Cys-273. Second, in addition to Nrf2 and Keap1, a third factor was deemed necessary for responding to three of the compounds. Finally, we isolated a zebrafish mutant defective in its response to seven compounds but not in response to the remaining four. These results led us to categorize Nrf2 activators into six classes and hypothesize that multiple sensing allows enhanced plasticity in the system.

Rutile-TiO2 nanocoating for a high-rate Li4Ti5O12 anode of a lithium-ion battery.

Abstract: Well-defined Li4Ti5O12 nanosheets terminated with rutile-TiO2 at the edges were synthesized by a facile solution-based method and revealed directly at atomic resolution by an advanced spherical aberration imaging technique. The rutile-TiO2 terminated Li4Ti5O12 nanosheets show much improved rate capability and specific capacity compared with pure Li4Ti5O12 nanosheets when used as anode materials for lithium ion batteries. The results here give clear evidence of the utility of rutile-TiO2 as a carbon-free coating layer to improve the kinetics of Li4Ti5O12 toward fast lithium insertion/extraction. The carbon-free nanocoating of rutile-TiO2 is highly effective in improving the electrochemical properties of Li4Ti5O12, promising advanced batteries with high volumetric energy density, high surface stability, and long cycle life compared with the commonly used carbon nanocoating in electrode materials.

Dectin-1 is required for host defense against Pneumocystis carinii but not against Candida albicans.

Abstract: Dectin-1 is a C-type lectin involved in the recognition of beta-glucans found in the cell walls of fungi. We generated dectin-1-deficient mice to determine the importance of dectin-1 in the defense against pathogenic fungi. In vitro, beta-glucan-induced cytokine production from wild-type dendritic cells and macrophages was abolished in cells homozygous for dectin-1 deficiency ('dectin-1-knockout' cells). In vivo, dectin-1-knockout mice were more susceptible than wild-type mice to pneumocystis infection, even though their cytokine production was normal. However, pneumocystis-infected dectin-1-knockout macrophages did show defective production of reactive oxygen species. In contrast to those results, wild-type and dectin-1-knockout mice were equally susceptible to candida infection. Thus, dectin-1 is required for immune responses to some fungal infections, as protective immunity to pneumocystis, but not to candida, required dectin-1 for the production of antifungal reactive oxygen species.

Interleukin-1 as a Pathogenetic Mediator of Ischemic Brain Damage in Rats

Abstract: Background and Purpose It has been suggested that interleukin-1 (IL-1) is a potent inflammatory mediator and that it is synthesized and secreted into the brain parenchyma. The aim of the present study is to evaluate the contribution of IL-1 to brain edema formation after focal brain ischemia. Methods The brain water content was measured to evaluate postischemic brain injury in rats after 60 minutes of middle cerebral artery occlusion and reperfusion. The effects of exogenous application of recombinant human interleukin-1β (rhIL-1β), anti–interleukin-1β neutralizing antibodies (anti–IL-1β), and the IL-1 blocker zinc protoporphyrin (ZnPP) on brain water content were observed, and histological technique was used to measure the infarction size and number of inflammatory cells infiltrated into the brain. Results Transient ischemia induced marked increase of brain water content, necrosis, and neutrophilic infiltration in the cortex perfused by the middle cerebral artery and the dorsal and ventral areas of the c...