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Melanin is an organic material biosynthesized from tyrosine in pigment-producing cells. The present study reports a simple method to generate tailored functional materials in mammalian cells by chemically fabricating intracellular melanin. Our approach exploits synthetic tyrosine derivatives to hijack the melanin biosynthesis pathway in pigment-producing cells. Its application was exemplified by synthesizing and using a paramagnetic tyrosine derivative, m-YR, which endowed melanoma cells with responsiveness to external magnetic fields. The mechanical force generated by the magnet-responsive melanin forced the cells to elongate and align parallel to the magnetic power lines. Critically, even non-pigment cells were similarly remote-controlled by external magnetic fields once engineered to express tyrosinase and treated with m-YR, suggesting the versatility of the approach. The present methodology may potentially provide a new avenue for mechanobiology and magnetogenetic studies and a framework for magnetic control of specific cells.

This case report describes the case of a 4-year-old toy poodle who underwent reconstruction using an autologous caudal vertebral graft for nonunion and osteomyelitis of a left radioulnar fracture. Radial reconstruction was performed 14 days after the removal of existing implants. Three autologous caudal vertebrae mounted onto a titanium T-plate were used to fill the radial bone defect. Rehabilitation was initiated 3 weeks after surgery. By the fifth week after surgery, the dog showed weight bearing on the affected limb. One year after the reconstruction surgery, revision surgery for replacing all implants was performed due to increased radiolucency of the graft. The dog remained clinically stable, and radiographic bone union was complete 3 years and 2 months after the first surgery. An autologous caudal vertebral graft was successfully used for the treatment of a large radial defect in a dog suffering from atrophic nonunion. Clinical improvement was prompt, and the long-term functional outcome was satisfactory.

We discovered new B-site-ordered double perovskites Ln2LiFeO6 (Ln = La, Nd, Sm, and Eu) with most likely unusually high valence Fe5+, which was stabilized by strong oxidizing high-pressure synthesis. Despite large antiferromagnetic interactions between Fe5+ spins in these compounds, the magnetic ordering is strongly suppressed due to the geometrical frustration of Fe5+ located in a face-centered cubic lattice. In addition, canted magnetic structures are stabilized only in those with Ln = Sm and Eu, which is most likely due to significant Dzyaloshinskii Moriya interaction caused by large monoclinic structural distortion. These results provide a deep understanding of the structure-property relationships in geometrically frustrated B-site-ordered double perovskites.

Two hexagonal-perovskite-structure oxides, 21R Ba7Fe5Ge2O20 and 12H Ba6Fe3Ge3O17, were obtained by synthesis with a high-pressure and high-temperature technique. The Fe-containing hexagonal-perovsk...

B-site-layer-ordered double perovskite Ca2FeMnO6 with unusually high valence Fe4+ was found to exhibit unusual oxygen-release behaviors, contrasting with those of the B-site-disordered perovskite having the identical chemical composition. During heating, the B-site-layer-ordered compound shows a stepwise oxygen release with successive valence changes from Fe4+ to Fe3+ through an intermediate Fe3.5+, whereas the B-site-disordered compound releases oxygen in a single step. The oxygen in Ca2FeMnO6 is released only from the two-dimensional Fe layers, and this selective oxygen release stabilizes the intermediate Fe3.5+ phase with in-plane-oxygen-vacancy ordering. Therefore, the B-site order/disorder strongly affects the oxygen-release behaviors associated with the oxygen-vacancy ordering.

The ambient pressure cation disordered InVO

We discovered new

Recently, Ag–Bi–I system has attracted significant attention as an emergent material for absorbers in solar cells. We have investigated the single-phase compositions, analyzed the detailed crystal structures, measured optical and electronic properties, and determined the structure–property relations of Ag2−3xBixI2. Single-phase samples with CdCl2-type rhombohedral structures were obtained with Ag-rich compositions (x = 0.45–0.48), while defect-spinel-type cubic structures were stabilized with Bi-rich compositions (x = 0.52–0.57). Both the rhombohedral and cubic structures consisted of the cubic close-packed I-ion sublattices, and the small difference in the Ag/Bi composition resulted in distinct crystal structures. Both the CdCl2-type rhombohedral and defect-spinel-type cubic compounds exhibited semiconducting behavior with proper band gap energies, which indicates that both materials are potentially useful as absorbers in solar cells. The rhombohedral structure compounds have shallower valence band energies, larger indirect band gap energies, and higher electrical conductivity with lower activation energy than the cubic structure compounds. The distinct properties result from the difference in the defect structures, additional Ag occupation in the rhombohedral phase and deficiencies of the octahedral site in the cubic phase.

The antiferromagnetic behavior of Fe3+ oxides of composition RE1.2Ba1.2Ca0.6Fe3O8, RE2.2Ba3.2Ca2.6Fe8O21, and REBa2Ca2Fe5O13 (RE = Gd, Tb) is highly influenced by the type of oxygen polyhedron around the Fe3+ cations and their ordering, which is coupled with the layered RE/Ba/Ca arrangement within the perovskite-related structure. Determination of the magnetic structures reveals different magnetic moments associated with Fe3+ spins in the different oxygen polyhedra (octahedron, tetrahedron, and square pyramid). The structural aspects impact on the strength of the Fe-O-Fe superexchange interactions and, therefore, on the Néel temperature (TN) of the compounds. The oxides present an interesting transition from three-dimensional (3D) to two-dimensional (2D) magnetic behavior above TN. The 2D magnetic interactions are stronger within the FeO6 octahedra layers than in the FeO4 tetrahedra layers., The antiferromagnetic behavior of Fe3+ oxides is highly influenced by the type of oxygen polyhedron around the Fe3+ cations and their ordering, which is coupled with the layered RE/Ba/Ca arrangement, within the perovskite-related structure in this striking (RE, Ba, Ca)3m+5nFe3m+5nO8m+13n (m, n) homologous series.

Caloric effects of solids can provide us with innovative refrigeration systems more efficient and environment-friendly than the widely-used conventional vapor-compression cooling systems. Exploring novel caloric materials is challenging but critically important in developing future technologies. Here we discovered that the quadruple perovskite structure ferrimagnet BiCu₃Cr₄O₁₂ shows large multiple caloric effects at the first-order charge transition occurring around 190 K. Large latent heat and the corresponding isothermal entropy change, 28.2 J K⁻¹ kg⁻¹, can be utilized by applying both magnetic fields (a magnetocaloric effect) and pressure (a barocaloric effect). Adiabatic temperature changes reach 3.9 K for the 50 kOe magnetic field and 4.8 K for the 4.9 kbar pressure, and thus highly efficient thermal controls are achieved in multiple ways., 磁場と圧力でマルチに冷却可能な酸化物新材料 --フェリ磁性電荷転移酸化物におけるマルチ熱量効果の実証--. 京都大学プレスリリース. 2021-06-22.

Transition metal nitrides are an important class of materials with applications as abrasives, semiconductors, superconductors, Li-ion conductors, and thermoelectrics. However, high oxidation states are difficult to attain as the oxidative potential of dinitrogen is limited by its high thermodynamic stability and chemical inertness. Here we present a versatile synthesis route using azide-mediated oxidation under pressure that is used to prepare the highly oxidised ternary nitride Ca4FeN4 containing Fe4+ ions. This nitridometallate features trigonal-planar [FeN3]5− anions with low-spin Fe4+ and antiferromagnetic ordering below a Neel temperature of 25 K, which are characterised by neutron diffraction, 57Fe-Mossbauer and magnetisation measurements. Azide-mediated high-pressure synthesis opens a way to the discovery of highly oxidised nitrides. High-valent metal nitrides are difficult to stabilise due to the high thermodynamic stability and chemical inertness of N2. Here, the authors employ a large volume press to prepare an iron(IV) nitridoferrate Ca4FeIVN4 from Fe2N and Ca3N2 via azide-mediated oxidation under high pressure conditions.

Two hexagonal-perovskite-structure oxides, 21R Ba

The mammalian cell nucleus is a highly organized organelle that contains membrane-less structures referred to as nuclear bodies (NBs). Some NBs carry specific RNA types that play architectural roles in their formation. Here, we show two types of RNase-sensitive DBC1-containing NBs, DBC1 nuclear body (DNB) in HCT116 cells and Sam68 nuclear body (SNB) in HeLa cells, that exhibit phase-separated features and are constructed using RNA polymerase I or II transcripts in a cell type-specific manner. We identified additional protein components present in DNB by immunoprecipitation-mass spectrometry, some of which (DBC1 and heterogeneous nuclear ribonucleoprotein L [HNRNPL]) are required for DNB formation. The rescue experiment using the truncated HNRNPL mutants revealed that two RNA-binding domains and intrinsically disordered regions of HNRNPL play significant roles in DNB formation. All these domains of HNRNPL promote in vitro droplet formation, suggesting the need for multivalent interactions between HNRNPL and RNA as well as proteins in DNB formation.

Oxygen contents in perovskite-structure Fe oxides can change in accordance with the valence states of Fe, i.e., AFeO3 with Fe4+, AFeO2.5 with Fe3+, and AFeO2 with Fe2+ (A = Ca and Sr). AFeO3 has a fully oxygenated simple-perovskite structure, and the unusual high valence Fe4+ in AFeO3 is easily reduced to relatively stable Fe3+ by releasing oxygen. On the other hand, AFeO2 has an infinite-layer structure, and the unusual square-planar coordination of Fe2+ in AFeO2 changes to tetrahedral and octahedral Fe3+ by incorporating oxygen. Sample weight measurements by thermogravimetry and corresponding phase analysis with synchrotron X-ray diffraction data revealed that the difference in the A-site cation strongly influenced the oxygen release and incorporation behaviors. In ambient air, topotactic changes of AFe4+O3 → AFe3+O2.5 ← AFe2+O2 for both A = Ca and Sr can occur by releasing and incorporating oxygen in the perovskite structure frameworks. Nonstoichiometric phases with oxygen vacancies are present between SrFeO3 and SrFeO2.5.

Transition metal nitrides are an important class of materials with applications as abrasives, semiconductors, superconductors, Li-ion conductors, and thermoelectrics. However, high oxidation states are difficult to attain as the oxidative potential of dinitrogen is limited by its high thermodynamic stability and chemical inertness. Here we present a versatile synthesis route using azide-mediated oxidation under pressure that is used to prepare the highly oxidised ternary nitride Ca4FeN4 containing Fe4+ ions. This nitridometallate features trigonal-planar [FeN3]5− anions with low-spin Fe4+ and antiferromagnetic ordering below a Neel temperature of 25 K, which are characterised by neutron diffraction, 57Fe-Mössbauer and magnetisation measurements. Azide-mediated high-pressure synthesis opens a way to the discovery of highly oxidised nitrides., High-valent metal nitrides are difficult to stabilise due to the high thermodynamic stability and chemical inertness of N2. Here, the authors employ a large volume press to prepare an iron(IV) nitridoferrate Ca4FeIVN4 from Fe2N and Ca3N2 via azide-mediated oxidation under high pressure conditions.

A fully oxygenated hexagonal 12-layer perovskite $\mathrm{BaFe}{\mathrm{O}}_{3}$ with nominal $\mathrm{F}{\mathrm{e}}^{4+}$ was obtained by high-pressure synthesis. The structure consists of face-sharing $\mathrm{F}{\mathrm{e}}_{3}{\mathrm{O}}_{9}$ octahedral trimers and corner-sharing octahedra. A remarkable series of electronic transitions that relieve the electronic instability of $\mathrm{F}{\mathrm{e}}^{4+}$ are discovered on cooling; $2\mathrm{F}{\mathrm{e}}^{4+}\ensuremath{\rightarrow}\mathrm{F}{\mathrm{e}}^{3+}+\mathrm{F}{\mathrm{e}}^{5+}$ charge disproportionation and ordering over two sites accompanied by a structural distortion at 500 K; charge disproportionation of the remaining $\mathrm{F}{\mathrm{e}}^{4+}$ with magnetic order at 280 K; and an unprecedented charge interchange where $\mathrm{F}{\mathrm{e}}^{3+}$ and $\mathrm{F}{\mathrm{e}}^{5+}$ states are exchanged between two sites with spin orientation change at 50 K. These properties demonstrate the presence of multiple competing ground states in this complex, highly condensed network of corner- and face-sharing octahedra.

Optically generated excitonic states (excitons and trions) in transition metal dichalcogenides are highly sensitive to the electronic and magnetic properties of the materials underneath. Modulation and control of the excitonic states in a novel van der Waals (vdW) heterostructure of monolayer MoSe2 on double-layered perovskite Mn oxide ((La0.8 Nd0.2 )1.2 Sr1.8 Mn2 O7 ) is demonstrated, wherein the Mn oxide transforms from a paramagnetic insulator to a ferromagnetic metal. A discontinuous change in the exciton photoluminescence intensity via dielectric screening is observed. Further, a relatively high trion intensity is discovered due to the charge transfer from metallic Mn oxide under the Curie temperature. Moreover, the vdW heterostructures with an ultrathin h-BN spacer layer demonstrate enhanced valley splitting and polarization of excitonic states due to the proximity effect of the ferromagnetic spins of Mn oxide. The controllable h-BN thickness in vdW heterostructures reveals a several-nanometer-long scale of charge transfer as well as a magnetic proximity effect. The vdW heterostructure allows modulation and control of the excitonic states via dielectric screening, charge carriers, and magnetic spins.

B-site-layer-ordered double perovskite Ca

A-site-layer-ordered double perovskite YBaCo2O6 with unusually high valence Co3.5+ was found to be an unusual ferromagnetic metal with strong electron correlation. The compound was obtained by topochemically oxidizing the A-site-layer-ordered YBaCo2O5, which contains nominal Co2.5+, in ozone at a low temperature. YBaCo2O6 crystallizes as a fully oxygenated A-site-layer-ordered double perovskite with a tetragonal structure at room temperature and shows an orthorhombic distortion below approximately 140 K. This anisotropic structural distortion induces ferromagnetic ordering of the mixed-valence Co spins with intermediate spin states, suggesting strong spin–lattice coupling in this system. In the ferromagnetic state, the up-spin band mainly consisting of hybridized Co 3d and O 2p crosses the Fermi level, giving the metallic behavior, regardless of the strong electron correlation.

BaFexNi1–xO3 with end members of BaNiO3 (x = 0) and BaFeO3 (x = 1), which, respectively, adopt the 2H and 6H hexagonal perovskite structures, were synthesized, and their crystal structures were investigated. A new single phase, Ba4Fe3NiO12 (x = 0.75), that adopts the 12R perovskite structure with the space group R3m (a = 5.66564(7) A and c = 27.8416(3) A), was found to be stabilized. Mossbauer spectroscopy results and structure analysis using synchrotron and neutron powder diffraction data revealed that nominal Fe3+ occupies the corner-sharing octahedral site while the unusually high valence Fe4+ and Ni4+ occupy the face-sharing octahedral sites in the trimers, giving a charge formula of Ba4Fe3+Fe4+2Ni4+O11.5. The magnetic properties of the compound are also discussed.

We performed 63,65Cu and 139La NMR measurements of T’-La1.8Eu0.2CuO 4 + δ (T’-LECO) with the Nd2CuO4-type structure (so-called T’-structure). As a result, we detected the 63,65Cu NMR signal under finite magnetic fields and found superconductivity without antiferromagnetic (AF) order only in the reduced T’-LECO, where excess apical oxygen atoms are properly removed. This indicates that the intrinsic ground state of the ideal T’-LECO is a paramagnetic and superconducting (SC) state. Below Tc, the Knight shift was found to rapidly decrease, which indicates the emergence of bulk superconductivity due to spin-singlet Cooper pairs in the reduced T’-LECO. In the SC state of the reduced T’-LECO, moreover, a characteristic temperature dependence of the spin-lattice relaxation rate 1/T1 was observed, which implies the existence of nodal lines in the SC gap. These findings suggest that the superconductivity in the reduced T’-LECO probably has d-wave symmetry. In the normal state of the reduced T’-LECO, on the other hand, AF fluctuations were found to exist from the temperature dependence of 1/T1T, though no clear pseudogap behavior was observed. This suggests that the AF correlation plays a key role in the superconductivity of undoped high-Tc cuprate superconductors with the T’-structure.