Processing and engineering applications of structured cellular ceramics through freezing route

We will report processing and engineering applications of cellular ceramics through freezing route, discussing in terms of: (1) the processing factors to create very high porosity up to 98vol% and the relationship between raw materials and slurry preparation; (2) the effect of freezing temperature and ice-binding additives on microstructures created; (3) the engineering applications of the cellular monoliths by using various starting materials, very low thermal conductivity, good electrochemical responses, dielectric and piezoelectric properties and improved strengths. In addition to that, the image based modelling techniques for mechanical properties and thermal conductivities of the resultant monoliths, based on actual microstructures collected by X-ray computed tomography, will be also studied, discussing those properties and cellular morphologies created by various freezing conditions. The simple, ecofriendly and versatile approach can modulate unique cellular architectures

Degenerate ground state in the classical pyrochlore antiferromagnet Na3_3Mn(CO3_3)2_2Cl

In an ideal classical pyrochlore antiferromagnet without perturbations, an infinite degeneracy at a ground state leads to absence of a magnetic order and spin-glass transition. Here we present Na$_3$Mn(CO$_3$)$_2$Cl as a new candidate compound where classical spins are coupled antiferromagnetically on the pyrochlore lattice, and report its structural and magnetic properties.The temperature dependences of the magnetic susceptibility and heat capacity, and the magnetization curve are consistent with those of an $S$ = 5/2 pyrochlore lattice antiferromagnet with nearest-neighbor interactions of 2 K. Neither an apparent signature of a spin-glass transition nor a magnetic order is detected in magnetization and heat capacity measurements, or powder neutron diffraction experiments. On the other hand, an antiferromagnetic short-range order from the nearest neighbors is evidenced by the $Q$-dependence of the diffuse scattering which develops around 0.85 \AA$^{-1}$. A high degeneracy near the ground state in Na$_3$Mn(CO$_3$)$_2$Cl is supported by the magnetic entropy estimated as almost 4 J K$^{-2}$ mol$^{-1}$ at 0.5 K.Comment: 9 pages, 7 figures, accepted to PR

Pile Response Characteristics of Liquefied Soil Layers in Shaking table Tests of a Large Scale Laminar Shear Box

To better understand the causes of pile damages during earthquakes such as Hyogoken-Nanbu Earthquake, shaking table tests of soil-pile-structure interaction models were done using a large scale laminar shear box. Because the pile response is affected by both the ground motion and the structure\u27s inertial forces, three models were test & a soil-pile model and two soil-pile-structure models. For the latter models, superstructures with long and short natural periods were tested separately. Through comparisons among the three cases, the influences on the pile response due to the inertial force of the superstructure for the long and short natural periods were clarified and properties of the subgrade reactions in liquefied ground were determined

Critical behavior of the metallic triangular-lattice Heisenberg antiferromagnet PdCrO2

We report physical properties of the conductive magnet PdCrO2 consisting of a layered structure with a triangular lattice of Cr3+ ions (S=3/2). We confirmed an antiferromagnetic transition at TN=37.5K by means of specific heat, electrical resistivity, magnetic susceptibility, and neutron scattering measurements. The critical behavior in the specific heat persists in an unusually wide temperature range above TN. This fact implies that spin correlations develop even at much higher temperature than TN. The observed sub-linear temperature dependence of the resistivity above TN is also attributed to the short-range correlations among the frustrated spins. While the critical exponent for the magnetization agrees reasonably with the prediction of the relevant model, that for the specific heat evaluated in the wide temperature range differs substantially from the prediction.Comment: 7 pages, 6 figure

Zero-point entropies of spin-jam and spin-glass states in a frustrated magnet

Thermodynamics of glassy states in a quasi-two-dimensional frustrated magnet Ba$_2$Sn$_2$ZnCr$_{7p}$Ga$_{10-7p}$O$_{22}$ where $p$ is the spin density are investigated experimentally. The system features a triangular network of bipyramids of spins with the quantum spin number $s = 3/2$. The DC magnetic susceptibility measurements on a series of samples with $0.44 \le p \le 0.98$ show a freezing transition with the transition temperature $T_\mathrm{f} \le 1.2$ K. $T_\mathrm{f}$ is found to decrease with decreasing $p$. The low-lying excitations in the glassy state of the system are examined via the temperature dependence of the magnetic heat capacity and are shown to consist of two components: the hydrodynamic Halperin-Saslow modes characteristic of a spin jam and the two-level systems of a spin glass. A continuous crossover between the two glassy states is observed via the varying weights of the two components as the spin density is varied. The $p$ dependence of the spin jam's zero-point entropy determined from the exotic perimeter-scaling behavior combined with the observed zero-point entropy of the samples provides the $p$ dependence of the spin glass's zero-point entropy. The obtained result shows that the correlations between orphan spins begin below $p \sim 0.8$, the limit that was also found using a neutron scattering technique in a previous report on the isostructural compound SrCr$_{9p}$Ga$_{12-9p}$O$_{19}$. The domain size of the spin-jam state estimated from the value of the zero-point entropy for the cleanest sample is approximately $4 \times 4$ bipyramids, about 2.5 times the measured spin correlation length

CXCL13-producing CD4⁺ T cells accumulate in the early phase of tertiary lymphoid structures in ovarian cancer

卵巣がんにおける新たな免疫の仕組みを発見 --三次リンパ様構造の形成メカニズムと予後への影響を解明--. 京都大学プレスリリース. 2022-08-05.Tertiary lymphoid structures (TLSs) are transient ectopic lymphoid aggregates whose formation might be caused by chronic inflammation states, such as cancer. However, how TLSs are induced in the tumor microenvironment (TME) and how they affect patient survival are not well understood. We investigated TLS distribution in relation to tumor infiltrating lymphocytes (TILs) and related gene expression in high grade serous ovarian cancer (HGSC) specimens. CXCL13 gene expression correlated with TLS presence and the infiltration of T cells and B cells, and was a favorable prognostic factor for HGSC patients. Coexistence of CD8⁺ T cells and B-cell lineages in the TME significantly improved the prognosis of HGSC and was correlated with the presence of TLSs. CXCL13 expression was predominantly coincident with CD4⁺ T cells in TLSs and CD8⁺ T cells in TILs, and shifted from CD4⁺ T cells to CD21⁺ follicular dendritic cells as TLS matured. In a mouse ovarian cancer model, recombinant CXCL13 induced TLSs and enhanced survival by the infiltration of CD8⁺ T cells. These results suggest that TLS formation was associated with CXCL13-producing CD4⁺ T cells and that TLSs facilitated the coordinated antitumor response of cellular and humoral immunity in ovarian cancer