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.

A Subaru Search for Lyα Blobs in and around the Protocluster Region At Redshift z = 3.1

Abstract: We report the properties of 35 robust candidate Lyα blobs (LABs), which are larger than 16 arcsec2 in isophotal area and brighter than 0.7 × 10-16 ergs s-1 cm-2, located in and around the protocluster region at redshift z = 3.1 discovered by Steidel et al. in the SSA22 field, based on wide-field (31' × 23') and deep narrowband (NB497; 4977 A, FWHM 77 A) and broadband (B, V, and R) images taken with the prime-focus camera on the Subaru Telescope. The two previously known giant LABs are the most luminous and the largest in our survey volume of 1.3 × 105 Mpc3. We reveal the internal structures of the two giant LABs and discover some bubble-like features, which suggest that intensive starburst and galactic superwind phenomena occurred in these objects in the past. The other 33 LABs have isophotal areas of ~16–78 arcsec2 and flux of (0.7–7) × 10-16 ergs s-1 cm-2. These 35 LABs show a continuous distribution of isophotal area and emission-line flux. The distributions of average surface brightness and morphology are widespread from relatively compact high surface brightness objects to very diffuse low surface brightness ones. The physical origins of these LABs may be (1) photoionization by massive stars or active galactic nuclei, or (2) cooling radiation from gravitationally heated gas, or (3) shock heating by starburst-driven galactic superwind. One-third of the LABs are apparently not associated with ultraviolet continuum sources that are bright enough to produce Lyα emission, assuming a Salpeter initial mass function. Of these LABs 90% are located inside the high surface density region of the 283 relatively compact and strong Lyα emitters selected in our previous study. This suggests that these LABs may be phenomena related to a dense environment at high redshift.

Nanofilm Allotrope and Phase Transformation of Ultrathin Bi Film on Si(111)-7×7

Abstract: Our scanning tunneling microscopy and electron diffraction experiments revealed that a new two-dimensional allotrope of Bi forms on the Si(111)-7x7 surface. This pseudocubic [012]-oriented allotrope is stable up to four atomic layers at room temperature. Above this critical thickness, the entire volume of the film starts to transform into a bulk single-crystal (001) phase, as the bulk contribution in the cohesion becomes dominant. Based on ab initio calculations, we propose that the new allotrope consists of black phosphorus-like puckered layers stabilized by saturating all the p(z) dangling bonds in the film.

Synergistic effect of Nod1 and Nod2 agonists with Toll-like receptor agonists on human dendritic cells to generate interleukin-12 and T helper type 1 cells

Abstract: A synthetic Nod2 agonist, muramyldipeptide (MDP), and two Nod1 agonists, FK565 and FK156, mimic the bacterial peptidoglycan moiety and are powerful adjuvants that induce cell-mediated immunity, especially delayed-type hypersensitivity. In this study, we used human dendritic cell (DC) cultures to examine possible T helper type 1 (Th1) responses induced by MDP and FK565/156 in combination with various synthetic Toll-like receptor (TLR) agonists, including synthetic lipid A (TLR4 agonist), the synthetic triacyl lipopeptide Pam3CSSNA (TLR2 agonist), poly(I:C) (TLR3 agonist), and CpG DNA (TLR9 agonist). Immature DCs derived from human monocytes expressed mRNAs for Nod1, Nod2, TLR2, TLR3, TLR4, and TLR9. The stimulation of DCs with MDP and FK565 in combination with lipid A, poly(I:C), and CpG DNA, but not with Pam3CSSNA, synergistically induced interleukin-12 (IL-12) p70 and gamma interferon (IFN-γ), but not IL-18, in culture supernatants and induced IL-15 on the cell surface. In correlation with the cytokine induction, an upregulation of the mRNA expression of these cytokine genes was observed. Notably, IL-12 p35 mRNA expression increased >1,000-fold upon stimulation with lipid A plus either MDP or FK565 compared with stimulation with each stimulant alone. In contrast, for the expression of CD83 and costimulatory molecules such as CD40, CD80, and CD86, no synergistic effects were observed upon stimulation with Nod plus TLR agonists. The culture supernatants of DCs stimulated with lipid A plus either MDP or FK565 activated human T cells to produce high levels of IFN-γ, and the activity was attributable to DC-derived IL-12. These findings suggest that Nod1 and Nod2 agonists in combination with TLR3, TLR4, and TLR9 agonists synergistically induce IL-12 and IFN-γ production in DCs to induce Th1-lineage immune responses.

Characteristics of carbohydrate degradation and the rate-limiting step in anaerobic digestion.

Abstract: The characteristics of the degradation of cellulose, soluble starch, and glucose in the acidogenic phase and the effects of the substrate loading rate and biological solids retention time on the methanogenic phase of anaerobic digestion were investigated. The results obtained from continuous experiments using laboratory-scale anaerobic chemostat reactors elucidated the true rate-limiting step of anaerobic digestion. The specific rate of substrate utilization decreased in the following order: glucose, soluble starch, acetic acid, and cellulose. The rate of the hydrolysis of cellulose was so low that this was shown to be the rate-limiting step in overall anaerobic digestion. Among methanogenic bacteria Methanosarcina would provide a higher substrate utilization rate than Methanothrix, and the maximum allowable substrate loading rate in the methanogenic phase was 11.2 g acetic acid/L day.

Lattice relaxation and energy band modulation in twisted bilayer graphene

Abstract: We theoretically study the lattice relaxation in the twisted bilayer graphene (TBG) and its effect on the electronic band structure. We develop an effective continuum theory to describe the lattice relaxation in general TBGs and obtain the optimized structure to minimize the total energy. At small rotation angles $l{2}^{\ensuremath{\circ}}$, in particular, we find that the relaxed lattice drastically reduces the area of the AA stacking region and forms a triangular domain structure with alternating AB and BA stacking regions. We then investigate the effect of the domain formation on the electronic band structure. The most notable change from the nonrelaxed model is that an energy gap of up to 20 meV opens at the superlattice subband edges on the electron and hole sides. We also find that the lattice relaxation significantly enhances the Fermi velocity, which was strongly suppressed in the nonrelaxed model.