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We have studied the magnetization of the recently discovered heavy fermion superconductor UTe 2 up to 56 T in pulsed-magnetic fields. A first-order metamagnetic transition has been clearly observed at H m =34.9 T when the magnetic field H is applied along the orthorhombic hard-magnetization b-axis. The transition has a critical end point at ∼11 K and 34.8 T, where the first order transition terminates and changes into a crossover regime. Using the thermodynamic Maxwell relation, we have evaluated the field dependence of the Sommerfeld coefficient of the specific heat directly related to the superconducting pairing. From the analysis, we found a significant enhancement of the effective mass centered at H m , which is reminiscent of the field-reentrant superconductivity of the ferromagnet URhGe in transverse fields. We discuss the origin of their field-robust superconductivity.

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We report here structural study on solvation of Mg 2+ ion in triglyme (G3)-based solutions applying as a novel electrolyte for rechargeable Mg batteries. In Mg(TFSA) 2 /G3 electrolyte solutions (TFSA = bis(trifluoromethanesulfonyl)amide), we found from Raman spectroscopy that Mg 2+ ion is solvated with two G3 molecules to form [Mg(G3) 2 ] 2+ complexes. No direct coordination of TFSA − anion to Mg 2+ ion occurs in the solutions with the salt concentrations c Mg = 0−1.60 M. The geometries and interaction energies for the [Mg(G3) 2 ] 2+ were evaluated by DFT calculations and indicated that G3 molecules in the most stable complex act as a tridentate ligand, i.e., octahedral [Mg(tri-G3) 2 ] 2+ . However, the Raman spectra implies that [Mg(tri-G3) 2 ] 2+ coexists with [Mg(tetra-G3) (bi-G3)] 2+ in the solutions where tetra-G3 and bi-G3 are G3 molecules acting as tetra-and bidentate ligands, respectively, in the solvation sphere. The Walden plots indicated that the dissociativity (or ionicity) of Mg(TFSA) 2 in G3 solutions increases with increasing c Mg , which is opposite to conventional organic electrolyte solutions but is similar to the LiTFSA/glyme solutions. ■ INTRODUCTIONMagnesium (Mg), one of the s-block elements that can exist as a divalent cation Mg 2+ has attracted attention in battery chemistry because of its high volumetric capacity, high negative reduction potential, and low cost relative to lithium-based batteries. To establish a practical rechargeable Mg battery system, it is well-recognized that the development of electrode materials and electrolytes using nonaqueous solvents play a key role and thus are now required to improve battery performance. In the latter viewpoints, the design of electrolyte is important to control ionic conductivity, ion diffusion, and solvation/ desolvation of metal ion at the electrode/electrolyte interface. The solvation/desolvation process of Mg ion is related to the charge transfer kinetics, i.e., dissolution/deposition behavior of Mg metal at the electrode, which controls current density directly. It is well-known that using Grignard reagents (R− Mg−X; R = alkyl groups and X = halides such as Br and Cl) Mg can be reversibly deposited in ethereal solvents such as tetrahydrofuran (THF) to give a rechargeable Mg battery system. 1 Aurbach et al. also proposed organo-haloaluminate salts such as Mg(AlCl 3 R) 2 or Mg(AlCl 2 RR′) in THF as promising electrolytes showing reversible dissolution/deposition of Mg. 2−5 Except for such electrolytes containing organoMg complexes, there have been no reports on reversible dissolution/deposition system using electrolyte solutions of simple MgX salts (X = ClO 4 , BF 4 , CF 3 SO 3 , etc.) in conventional nonaqueous solvents (propylene carbonate, acetonitrile, N,N-dimethylformamide, etc.) similar to electrolytes for Li ion batteries. 6 Recently, a system using simple Mg salt with bis(trifluoromethanesulfonyl)amide (TFSA) anion, Mg(TFSA) 2 , in dimethoxy ethylene (glyme)-type solvents was reported as a promising electrolyte for rechargeable Mg b...

Osteoblasts produce calcified bone matrix and contribute to bone formation and remodeling. In this study, we established a procedure to directly convert human fibroblasts into osteoblasts by transducing some defined factors and culturing in osteogenic medium. Osteoblast-specific transcription factors, Runt-related transcription factor 2 (Runx2), and Osterix, in combination with Octamer-binding transcription factor 3/4 (Oct4) and L-Myc (RXOL) transduction, converted ∼80% of the fibroblasts into osteocalcin-producing cells. The directly converted osteoblasts (dOBs) induced by RXOL displayed a similar gene expression profile as normal human osteoblasts and contributed to bone repair after transplantation into immunodeficient mice at artificial bone defect lesions. The dOBs expressed endogenous Runx2 and Osterix, and did not require continuous expression of the exogenous genes to maintain their phenotype. Another combination, Oct4 plus L-Myc (OL), also induced fibroblasts to produce bone matrix, but the OL-transduced cells did not express Osterix and exhibited a more distant gene expression profile to osteoblasts compared with RXOL-transduced cells. These findings strongly suggest successful direct reprogramming of fibroblasts into functional osteoblasts by RXOL, a technology that may provide bone regeneration therapy against bone disorders.O steoblasts play a central role in bone formation and remodeling by producing type I collagen, osteopontin, osteocalcin, and bone sialoprotein (BSP), and calcifying these bone matrixes (1). They are also involved in hematopoiesis, phosphate metabolism, and glucose metabolism (2). Osteoblasts are derived from mesenchymal progenitor cells that are common precursors shared by chondrocytes, adipocytes, and myoblasts (3). The differentiation of osteoblasts is regulated by various transcription factors, including Runt-related transcription factor 2 [Runx2, also known as core-binding factor subunit α-1 (Cbfα-1)] (4, 5), Osterix (6, 7), Distal-less homeobox 5 (Dlx5) (8), and activation transcription factor 4 (ATF-4) (8). A functional decline in osteoblasts relative to osteoclasts results in imbalance between bone formation and resorption and may cause osteolytic pathological conditions, such as osteoporosis (9), alveolar bone resorption associated with periodontitis (10), and bone lysing associated with bone tumors, including multiple myeloma (11).It has been demonstrated that forced expression of combinations of some transcription factors, such as Octamer-binding transcription factor 3/4 (Oct4), Sox2, Klf-4, and c-Myc (reprogramming factors), induces immortality and pluripotency in mammalian somatic cells (12, 13). The generation of induced pluripotent stem (iPS) cells clearly indicates that genome-wide epigenetic programming can be drastically changed in somatic cells by a small number of transcription factors that may have key regulatory roles in cell fate decisions (14,15).Recent studies have reported that direct conversion, or direct reprogramming, of somatic cells into another dif...

Thin crystalline silicon (c‐Si) solar cells are highly attractive for realizing light‐weight and flexible wafer‐based solar cells as well as for reducing the material cost. Silicon heterojunction (SHJ) architecture using hydrogenated amorphous silicon (a‐Si:H) is suitable for realizing very thin c‐Si cells, because of its capability of excellent surface passivation. In this work, the potential of very thin c‐Si solar cells is examined by characterizing SHJ solar cells with a wide range of thicknesses from 50 to 400 μm. A trade‐off between the open‐circuit voltage (VOC) and the short circuit current density (JSC) against wafer thickness is clearly observed in these SHJ cells, whereas a decrease in fill factor (FF) is found for thin SHJ cells below 80 μm. The loss analysis for the thin SHJ cells with numerical simulation clarifies that the infrared parasitic absorption loss due to the supporting layers is enhanced for thinner wafers, which limits the JSC in the thin SHJ cells. In addition, it is confirmed that the FF is more sensitive to surface recombination than the VOC, and this tendency becomes more pronounced with the decrease in the wafer thickness. A high efficiency of 22% is achieved in a SHJ solar cell with a thickness of only 46 μm, demonstrating a high potential for flexible high‐efficiency c‐Si solar cells.

We performed AC calorimetry and magnetoresistance measurements under pressure for H a-axis (easymagnetization axis) in the novel heavy-fermion superconductor UTe 2 . Thanks to the thermodynamic information, multiple superconducting phases have been revealed under pressure and magnetic field. The (H, T ) phase diagram of superconductivity under pressure displays an abrupt increase of the upper critical field (H c2 ) at low temperature and in the high field region, and a strong convex curvature of H c2 at high temperature. This behavior of H c2 and the multiple superconducting phases require a state for the spin-triplet superconducting order parameter more complex than an equal spin pairing. Above the superconducting critical pressure, P c , we find strong indications that the possible magnetic order is closer to antiferromagnetism than to ferromagnetism.The recently discovered heavy-fermion superconductivity (SC) in UTe 2 attracts much attention, 1, 2) because spin-triplet SC is most likely realized in this system, lying at the proximity of ferromagnetic (FM) order. SC coexisting microscopically with long-range FM order is already well studied 3, 4) in three uranium compounds, UGe 2 , 5) URhGe 6) and UCoGe. 7) Because of the strong internal field due to the FM moment, spin-triplet state with equal-spin pairing (ESP) is favoured. In this case, SC can survive even under strong internal exchange field. Furthermore SC can be even reinforced at high magnetic field (H), pressure (P) and uniaxial stress by tuning the FM fluctuations. When the field is applied along the intermediate hard-magnetization axis (b-axis) in URhGe and UCoGe, the FM Curie temperature is suppressed, and the FM fluctuations are remarkably enhanced. Then field-reentrant (-reinforced) SC is observed at high fields, which highly exceeds the socalled Pauli limit. 8,9) A quite similar situation might be also realized in UTe 2 . UTe 2 is a paramagnet with a body-centered orthorhombic crystal structure (space group: Immm, #71, D 25 2h ). The large Sommerfeld coefficient, γ ∼ 120 mJ K −2 mol −1 , indicates strong correlations in the electronic states. 10) The magnetization curves show a relatively large anisotropy between the easy-magnetization axis (a-axis) and the hard-magnetization axes (b and c-axes). The b-axis is the hardest magnetization axis at low temperatures; the magnetization curve shows sharp 1st order metamagnetic transition at H m = 35 T, where the effective mass is strongly enhanced. [11][12][13] The value of H m is well scaled by T χ max (∼ 35 K), at which a broad maximum of susceptibility χ is observed at low field.The SC properties of UTe 2 are spectacular. The SC transition occurs at T sc = 1.6 K with the large specific heat jump. The residual γ-value amounts to ∼ 40 % against the normal state γ-value for the best quality sample, 14) and the entropy balance is not satisfied, assuming a constant γ-value extrapolated from the normal state above T sc . Strong electronic correlations are dominant in this system, which is also indirectly con...

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