Cascade Charge Transitions of Unusually High and Mixed Valence Fe3.5+ in the A-Site Layer-Ordered Double Perovskite SmBaFe2O6.

The A-site layer-ordered double perovskite SmBaFe2O6 was obtained by topochemical of oxidizing A-site layer-ordered SmBaFe2O5 in ozone at a low temperature. The compound contained unusually high and mixed valence Fe3.5+ and was found to show cascade charge transitions, described as SmBaFe3.5+2O6 → SmBa(Fe3+Fe4+)O6 → SmBa(Fe3+Fe(4-δ)+0.5Fe(4+δ)+0.5)O6 → SmBa(Fe3+1.5Fe5+0.5)O6, to relieve its electronic instability. The first Verwey-like charge-order transition occurred at 340 K and was accompanied by a significant structural change and a sudden increase in magnetic susceptibility. The following transition was the charge disproportionation of metastable Fe4+ to Fe3+ and Fe5+, and each of the spins resulted in the antiferromagnetic ground state. The most plausible charge-ordered patterns are proposed based on the electrostatic lattice energy calculations.

High-Pressure Synthesized Perovskite CdMnO3 with C-Type Antiferromagnetic Spin Configuration.

CdMnO3 had not been previously reported and was a missing piece in the A2+Mn4+O3 series. We succeeded in synthesizing this compound by a high-pressure method and confirmed that it is crystallized in a distorted perovskite structure with a Cd2+Mn4+O3 charge configuration. The obtained insulating CdMnO3 exhibits an antiferromagnetic transition at about 86 K. First-principles calculations revealed that the Mn4+ (t2g3) spins form a C-type antiferromagnetic structure, which is in sharp contrast to the G-type antiferromagnetism in the isostructural and isoelectronic CaMnO3. Significant overlap of the Mn-3d and O(2)-2p orbitals produces distorted octahedra with a large Mn-O(1)-Mn tilt and induces antiferromagnetic couplings in the ac plane and the ferromagnetic couplings along the b axis.

Magnetic Control of Cells by Chemical Fabrication of Melanin.

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.

Unexpectedly Large Contribution of Oxygen to Charge Compensation Triggered by Structural Disordering: Detailed Experimental and Theoretical Study on a Li3NbO4-NiO Binary System.

Dependence on lithium-ion batteries for automobile applications is rapidly increasing. The emerging use of anionic redox can boost the energy density of batteries, but the fundamental origin of anionic redox is still under debate. Moreover, to realize anionic redox, many reported electrode materials rely on manganese ions through π-type interactions with oxygen. Here, through a systematic experimental and theoretical study on a binary system of Li3NbO4-NiO, we demonstrate for the first time the unexpectedly large contribution of oxygen to charge compensation for electrochemical oxidation in Ni-based materials. In general, for Ni-based materials, e.g., LiNiO2, charge compensation is achieved mainly by Ni oxidation, with a lower contribution from oxygen. In contrast, for Li3NbO4-NiO, oxygen-based charge compensation is triggered by structural disordering and σ-type interactions with nickel ions, which are associated with a unique environment for oxygen, i.e., a linear Ni-O-Ni configuration in the disordered system. Reversible anionic redox with a small hysteretic behavior was achieved for LiNi2/3Nb1/3O2 with a cation-disordered Li/Ni arrangement. Further Li enrichment in the structure destabilizes anionic redox and leads to irreversible oxygen loss due to the disappearance of the linear Ni-O-Ni configuration and the formation of unstable Ni ions with high oxidation states. On the basis of these results, we discuss the possibility of using σ-type interactions for anionic redox to design advanced electrode materials for high-energy lithium-ion batteries.

LiNbO3 -Type Polar Antiferromagnet InVO3 Synthesized under High-Pressure Conditions.

The ambient pressure cation disordered InVO3 bixbyite has been predicted to form a GdFeO3 -type perovskite phase under high pressure and high temperature. Contrary to the expectation, InVO3 was found to crystallize in the polar LiNbO3 -type structure with a calculated spontaneous polarization as large as 74 µC cm-2 . Antiferromagnetic coupling of V3+ magnetic moments and a cooperative magnetic ground state below about 10 K coupled with a polar structure suggest an intriguing ground state of the novel LiNbO3 -type high-pressure InVO3 structure.

Geometrical Spin Frustration and Monoclinic-Distortion-Induced Spin Canting in the Double Perovskites Ln2LiFeO6 (Ln = La, Nd, Sm, and Eu) with Unusually High Valence Fe5.

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.

Distinct RNA polymerase transcripts direct the assembly of phase-separated DBC1 nuclear bodies in different cell lines.

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.

Giant multiple caloric effects in charge transition ferrimagnet.

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.

3D to 2D Magnetic Ordering of Fe3+ Oxides Induced by Their Layered Perovskite Structure.

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.

Preparation of iron(IV) nitridoferrate Ca4FeN4 through azide-mediated oxidation under high-pressure conditions.

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.

Layered Hexagonal Perovskite Oxides 21R Ba7Fe5Ge2O20 and 12H Ba6Fe3Ge3O17.

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-perovskite-structure units are sandwiched by nonmagnetic GeO4 tetrahedral layers in the structures, and thus both compounds show two-dimensional ferrimagnetic behaviors due to intra- and interunit magnetic interactions. 21R Ba7Fe5Ge2O20 has the ionic formula Ba7Fe123+Fe24+Fe324+Ge424+O20 at room temperature, and unusually high valence Fe4+ in the trimers undergoes charge disproportionation, Fe24+ + 2Fe34+ → Fe2(4+2δ)+ + 2Fe3(4-δ)+, at low temperatures. In contrast, 12H Ba6Fe3Ge3O17 with ionic formula Ba6Fe123+(Fe20.54+Ge20.54+)2Ge324+O17 does not show a charge transition.

Controllable Magnetic Proximity Effect and Charge Transfer in 2D Semiconductor and Double-Layered Perovskite Manganese Oxide van der Waals Heterostructure.

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.

Successive and Site-Selective Oxygen Release from B-Site-Layer-Ordered Double Perovskite Ca2FeMnO6 with Unusually High Valence Fe4.

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.

Hexagonal Perovskite Ba4Fe3NiO12 Containing Tetravalent Fe and Ni Ions.

BaFe xNi1- 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 R3̅ m ( a = 5.66564(7) Å and c = 27.8416(3) Å), was found to be stabilized. Mössbauer 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.

Successful transition from Treprostinil to Selexipag in patient with severe pulmonary arterial hypertension.

BACKGROUND: In this report, we describe the first successful case of transition from subcutaneous administration of treprostinil to selexipag in a patient with severe pulmonary arterial hypertension (PAH), by evaluating hemodynamic changes and exercise tolerance. CASE PRESENTATION: A 38-year-old female with idiopathic PAH (IPAH) had received initial triple combination therapy (macitentan PO, tadalafil PO, and treprostinil SC) and achieved excellent improvement in hemodynamics. Afterwards, due to the development of side effects from subcutaneous administration, we replaced treprostinil therapy with oral selexipag, resulting in stable hemodynamic parameters and exercise capacities. CONCLUSIONS: We report the first case of successful replacement of treprostinil (20.1 ng/kg/min) with selexipag (1600 µg BID) as a component of triple combination therapy, which provides incentive to perform a larger, prospective exchange study.

Incidence and predictors of rehospitalization of acute heart failure patients.

Repeated hospitalization due to acute decompensated heart failure (HF) is a pandemic health problem in Japan. However, it is difficult to predict rehospitalization after discharge for acute decompensated HF. We used a single hospital-based cohort from the Shinken Database 2004-2012, comprising all new patients (n = 19,994) who visited the Cardiovascular Institute Hospital. A total of 282 patients discharged after their first acute HF admission were included in the analysis. The median follow-up period was 908 ± 865 days. Of these patients, rehospitalization due to worsening HF occurred in 55 patients. The cumulative rate of rehospitalization was 17.5% at 1 year, 21.4% at 2 years, and 25.5% at 3 years. Patients with rehospitalization were older than those without rehospitalization. Prevalence of diabetes mellitus (DM) was more common in patients with rehospitalization. Average heart rate (HR) tended to be higher in patients with rehospitalization. Loop diuretics were more commonly used at hospital discharge in patients with rehospitalization. Multivariate Cox regression analysis revealed that age ≥ 75 years, DM, HR ≥ 75 bpm at discharge, and use of loop diuretics at discharge were independent predictors for rehospitalization. The number of these independent risk factors could be used to clearly discriminate between the HF rehospitalization low-, middle- and high-risk patients. HF rehospitalization commonly occurred in patients who were discharged after their first acute HF admission. Older age, DM, increased HR, and loop diuretics use at discharge were independently associated with HF rehospitalization. By simply counting these risk factors, we might be able to predict the risk of HF rehospitalization after discharge.

Mammalian serum albumins as a chiral mediator library for bio-supramolecular photochirogenesis: optimizing enantiodifferentiating photocyclodimerization of 2-anthracenecarboxylate.

A simple strategy for choosing optimal bio-supramolecular mediators from the mammalian serum albumin library is proposed for bimolecular photochirogenic reactions. Thus, the enantiodifferentiating photocyclodimerization of 2-anthracencecarboxylate (AC) was optimized in chemical and optical yields, when mediated by porcine and canine serum albumins, both of which bound two AC molecules in the first productive site to give the (P)-enantiomer of syn-head-to-tail-cyclodimer in 69% yield and 89% enantiomeric excess (ee) for the former but the (M)-enantiomer in 77% yield and 97% ee for the latter.

Presentations and outcomes of patients with acute decompensated heart failure admitted in the winter season.

BACKGROUND: Seasonal variations in cardiovascular disease is well recognized. However, little is known about the presentations and outcomes of Japanese heart failure (HF) patients in the winter season. METHODS AND RESULTS: We used a single hospital-based cohort from the Shinken Database 2004-2012, comprising all new patients (n=19,994) who visited the Cardiovascular Institute Hospital. A total of 375 patients who were admitted owing to acute decompensated HF were included in the analysis. Of these patients, 136 (36%) were admitted in winter. Winter was defined as the period between December and February. The HF patients admitted in winter were older, and had a higher prevalence of hypertension and diabetes mellitus than the patients admitted in other seasons. Patients with conditions categorized as clinical scenario 1 tended to be admitted more commonly in winter. HF with preserved left ventricular ejection fraction (LVEF) was more common in HF patients admitted in winter than in those admitted in other seasons. Beta-blocker use at hospital discharge was more common in the patients admitted in other seasons. Kaplan-Meier curves and log-rank test results indicated that the incidences of all-cause death, cardiovascular death, and HF admission were comparable between the patients admitted in winter and those admitted in other seasons. CONCLUSIONS: HF admission was frequently observed in the winter season and HF patients admitted in the winter season were older, and had higher prevalence of hypertension and diabetes mellitus, and preserved LVEF suggesting that we might need to pay more attention for elderly patients with hypertension, diabetes mellitus, and HF with preserved LVEF to decrease HF admissions in the winter season.

Synergistic effects of high hydrostatic pressure, mild heating, and amino acids on germination and inactivation of Clostridium sporogenes spores.

The synergistic effects of high hydrostatic pressure (HHP), mild heating, and amino acids on the germination of Clostridium sporogenes spores were examined by determining the number of surviving spores that returned to vegetative growth after pasteurization following these treatments. Pressurization at 200 MPa at a temperature higher than 40°C and treatment with some of the 19 l-amino acids at 10 mM or higher synergistically facilitated germination. When one of these factors was omitted, the level of germination was insignificant. Pressures of 100 and 400 MPa were less effective than 200 MPa. The spores were effectively inactivated by between 1.8 and 4.8 logs by pasteurization at 80°C after pressurization at 200 MPa at 45°C for 120 min with one of the amino acids with moderate hydrophobicity, such as Leu, Phe, Cys Met, Ala, Gly, or Ser. However, other amino acids showed poor inactivation effects of less than 0.9 logs. Spores in solutions containing 80 mM of either Leu, Phe, Cys, Met, Ala, Gly, or Ser were successfully inactivated by pasteurization by more than 5.4 logs after pressurization at 200 MPa at 70°C for 15 to 120 min. Ala and Met reduced the spore viability by 2.8 and 1.8 logs, respectively, by pasteurization at a concentration of 1 mM under 200 MPa at 70°C. These results indicate that germination of the spores is facilitated by a combination of high hydrostatic pressure, mild heating, and amino acids.