Cyclic Heterometallic Interactions formed from a Flexible Tripeptide Complex Showing Effective Antiferromagnetic Spin Coupling.

Developing tunable motifs for heterometallic interactions should be beneficial for fabricating functional materials based on cooperative electronic communications between metal centers. Reported here is the efficient formation of cyclic heterometallic interactions from a complex containing an artificial tripeptide with metal binding sites on its main chain and side chains. X-ray structural analysis and X-ray absorption spectroscopy revealed that the cyclic metal-metal arrangements arise from the amide groups connecting four square-planar CuII centers and four octahedral NiII centers in a cyclic manner. UV/Vis spectral studies suggested that this efficient formation was achieved by the selective formation of the square-planar CuII centers and a crystallization process. Magnetic measurements using SQUID clarified that the cyclic complex represented the S=2 spin state at low temperatures due to effective antiferromagnetic interactions between the NiII and CuII centers.

Alternative Route Triggering Multistep Spin Crossover with Hysteresis in an Iron(II) Family Mediated by Flexible Anion Ordering.

Multistep spin crossover (SCO) compounds have attracted much attention, since they can be great candidates for high-density multinary memory devices. The introduction of substituents, such as methyl (Me), chloro (Cl), bromo (Br), and methoxy (MeO) groups, at para positions to the phenyl-substituted tripodal N6 ligand-coordinated SCO FeII material, [FeLPh](NTf2)2 [where LPh = tris(2-{[(1-phenyl-1H-1,2,3-triazol-4-yl)methylidene]amino}ethyl)amine and NTf2 = bis(trifluoromethanesulfonyl)imide], affords a new family of solvent-free FeII complexes: [FeL4-R-Ph](NTf2)2 {where L4-R-Ph = tris[2-({[1-(4-R-phenyl)-1H-1,2,3-triazol-4-yl]methylidene}amino)ethyl]amine, where R = Me (1), Cl (2), Br (3), and MeO (4)}. 1 shows temperature invariant high-spin (HS) state, whereas the others show spin transitions with different characteristics, such as half-SCO (4), two-step SCO (3), and unusual three-step SCO with hysteresis (2). Mössbauer and X-ray absorption fine structure (XAFS) spectroscopic studies of them support the magnetic susceptibilities results. Density functional theory calculations indicate that the electronic effect of different substituents on magnetic properties is negligible in this FeII family. Single-crystal X-ray diffraction studies reveal that 1-4 has a similar packing arrangement with three-dimensional supramolecular network via intermolecular π-π and CH···π interactions between complex cations, and CH···X (X = O, N, and F) hydrogen bonding interactions between cations and inherently frustrated NTf2 anions. Variable-temperature structural studies unveil a variety of stepped SCO behaviors of 2-4 and deactivation of SCO in 1 are governed by the regulation of ordering of NTf2 counteranions through the subtle modification of terminal substituents of complex cations. Quantitative light-induced excited spin-state trapping (LIESST) effect was observed for 2-4 via green light irradiation (532 nm) at 10 K. This study opens up a new way for systematic control of magnetic response from no SCO to half-, two-step, and finally three-step SCO with hysteresis by precise tuning of the ordering of flexible NTf2 anions included in the supramolecular network with potentially SCO-active complex cations.

Understanding voltage-controlled magnetic anisotropy effect at Co/oxide interface.

The voltage-controlled magnetic anisotropy (VCMA) effect is a key to realising high-speed, ultralow-power consumption spintronic devices. The fcc-Co-(111)-based stack is a promising candidate for the achievement of large VCMA coefficients. However, only a few studies on the fcc-Co-(111)-based stack have been reported and the VCMA effect has not been well understood. Previously, we observed a significant increase in the voltage-controlled coercivity (VCC) in the Pt/Ru/Co/CoO/TiOx structure upon post-annealing. However, the mechanism underlying this enhancement remains unclear. This study performs multiprobe analyses on this structure before and after post-annealing and discusses the origin of the VCMA effect at the Co/oxide interface. X-ray magnetic circular dichroism measurement revealed an increase in the orbital magnetic moment owing to post-annealing, accompanied by a significant increase in VCC. We speculate that the diffusion of Pt atoms into the vicinity of Co/oxide interface enhances the interfacial orbital magnetic moment and the VCMA at the interface. These results provide a guideline for designing structures to obtain a large VCMA effect in fcc-Co-(111)-based stacks.

Intrinsic Magnetic Proximity Effect at the Atomically Sharp Interface of CoxFe3-xO4/Pt Grown by Molecular Beam Epitaxy.

CoxFe3-xO4(CFO)/Pt bilayers prepared by molecular beam epitaxy were investigated for the anomalous Hall effect and X-ray magnetic circular dichroism (XMCD). We found that the anomalous Hall effect originates from a magnetic proximity effect at the CFO/Pt interface. The XMCD signal in the Pt L-edge was obtained only for the sample deposited at 600 °C, indicating that the magnetic proximity effect is sensitive to the interface structure. Transmission electron microscopy images of the CFO/Pt interface and XMCD measurements of Co and Fe L-edges do not provide direct evidence for interfacial atomic diffusion or alloying. In summary, these results suggest that the magnetic proximity effect is robust for transport properties, such as the anomalous Hall effect, while the induced magnetic moment depends on slight differences in the interfacial structure, such as the presence or absence of interfacial oxygen ions.

Understanding magnetocrystalline anisotropy based on orbital and quadrupole moments.

Understanding magnetocrystalline anisotropy (MCA) is fundamentally important for developing novel magnetic materials. Therefore, clarifying the relationship between MCA and local physical quantities observed by spectroscopic measurements, such as the orbital and quadrupole moments, is necessary. In this review, we discuss MCA and the distortion effects in magnetic materials with transition metals (TMs) based on the orbital and quadrupole moments, which are related to the spin-conserving and spin-flip terms in the second-order perturbation calculations, respectively. We revealed that orbital moment stabilized the spin moment in the direction of the larger orbital moment, while the quadrupole moment stabilized the spin moment along the longitudinal direction of the spin-density distribution. The MCA of the magnetic materials with TMs and their interfaces can be determined from the competition between these two contributions. We showed that the perpendicular MCA of the face-centered cubic Ni with tensile tetragonal distortion arose from the orbital moment anisotropy, whereas that of Mn-Ga alloys originated from the quadrupole moment of spin density. In contrast, in the Co/Pd(111) multilayer and Fe/MgO(001), both the orbital moment anisotropy and quadrupole moment of spin density at the interfaces contributed to the perpendicular MCA. Understanding the MCA of magnetic materials and interfaces based on orbital and quadrupole moments is essential to design MCA of novel magnetic applications.

Detecting quadrupole: a hidden source of magnetic anisotropy for Manganese alloys.

Mn-based alloys exhibit unique properties in the spintronics materials possessing perpendicular magnetic anisotropy (PMA) beyond the Fe and Co-based alloys. It is desired to figure out the quantum physics of PMA inherent to Mn-based alloys, which have never been reported. Here, the origin of PMA in ferrimagnetic Mn3- δ Ga ordered alloys is investigated to resolve antiparallel-coupled Mn sites using x-ray magnetic circular and linear dichroism (XMCD/XMLD) and a first-principles calculation. We found that the contribution of orbital magnetic moments in PMA is small from XMCD and that the finite quadrupole-like orbital distortion through spin-flipped electron hopping is dominant from XMLD and theoretical calculations. These findings suggest that the spin-flipped orbital quadrupole formations originate from the PMA in Mn3- δ Ga and bring the paradigm shift in the researches of PMA materials using x-ray magnetic spectroscopies.

Preparation of Hierarchically Assembled Silver Nanostructures based on the Morphologies of Crystalline Peptide-Silver(I) Complexes.

The preparation of a hierarchically assembled Ag nanostructures based on a nanocrystalline assembly was demonstrated using an Ag(I) complex of a dipeptide (AspDap). By heating under N2 gas, a spherical assembly of a nanocrystalline dipeptide-Ag(I) complex (diameter 4-5 µm), which has a morphology similar to the assembled structure of the dipeptide, was transformed to an assembly of Ag nanostructures, where the micrometre-order crystalline morphology was maintained. In addition, detailed scanning electron microscopy studies revealed that Ag nanoparticles (diameter ca. 10 nm) were formed on the surface of the Ag nanostructure. When the Ag(I) ions were reduced to Ag(0), this phenomenon exhibited surface dependence due to the anisotropic two-dimensional Ag(I) arrangement in the crystals. Thermogravimetric measurements and X-ray photoelectron spectroscopy revealed that the reduction proceeds in a stepwise manner around 200-250 °C, together with the removal of primary and secondary carboxylic groups in the dipeptide. Comparison with the heating process of the crystalline Ag(I) complex of ß-alanine indicated that stepwise reduction is key for maintaining the original micrometre-order morphology.

Anatomy of interfacial spin-orbit coupling in Co/Pd multilayers using X-ray magnetic circular dichroism and first-principles calculations.

Element-specific orbital magnetic moments and their anisotropies in perpendicularly magnetised Co/Pd multilayers are investigated using Co L-edge and Pd M-edge angle-dependent x-ray magnetic circular dichroism. We show that the orbital magnetic moments in Co are anisotropic, whereas those in Pd are isotropic. The first-principles density-functional-theory calculations also suggest that the Co/Pd interfacial orbital magnetic moments in Co are anisotropic and contribute to the perpendicular magnetic anisotropy (PMA), and that the isotropic ones in Pd manipulates the Co orbitals at the interface through proximity effects. Orbital-resolved anatomy of Co/Pd interfaces reveals that the orbital moment anisotropy in Co and spin-flipped transition related to the magnetic dipoles in Pd are essential for the appearance of PMA.

[An autopsy case of microscopic polyangiitis complicated with pulmonary aspergilloma and cytomegalovirus pneumonia].

A 71-year-old man was admitted to our hospital because of fever and rapidly progressive renal insufficiency over a month. He had depression and Alzheimer's disease as complications. On admission, his serum creatinine was 5.4 mg/dL, and the serum CRP and MPO-ANCA were 18.2 mg/dL and 285 EU, respectively. A computed tomographic chest scan showed pericardiac effusion and fibrosis in both lower lung fields. Although microscopic polyangiitis(MPA)was inferred from a positive MPO-ANCA, renal biopsy could not be carried out. The initial therapy was started with pulse methylprednisolone therapy, followed by oral administration of prednisolone at the dose of 1 mg/kg(60 mg/day). As a result, his fever and inflammatory findings disappeared, and renal insufficiency was ameliorated with a smooth recovery and the pericardial effusion was markedly diminished. However, on the 18th hospital day, chest radiography revealed a nodular shadow in the right lung. Fungus infection was suspected because his serum beta-D-glucan level was extremely high (above 999 pg/mL). Mikafungin, therefore, was started at a dose of 75 mg/day and then, the dose was increased up to 300 mg/day. Nevertheless, he finally died of respiratory failure on the 26th hospital day. The autopsy findings revealed a cavity of 4.0 x 3.0 x 3.0 centimeters in size in the upper lobe of the right lung. There was a great number of fungal threads with a septal wall branched in a Y-shaped figure around the cavity, thus indicating pulmonary aspergilloma. Intranuclear inclusion bodies staining positive for cytomegalovirus were observed in all the lung fields, suggestive of a cytomegalovirus infection. In the kidney, a cellular crescent formation was noted in the majority of glomeruli showing crescentic glomeluronephritis, compatible with MPA.

Induced perpendicular magnetization in a Cu layer inserted between Co and Pt layers revealed by x-ray magnetic circular dichroism.

We used x-ray absorption spectroscopy and x-ray magnetic circular dichroism to investigate the effects of inserting Cu into Co/Pt interfaces, and found that a 0.4-nm-thick inserted Cu layer showed perpendicularly magnetized properties induced by the proximity effect through the Co and Pt layers. The dependence of the magnetic properties on the thickness of the Cu layers showed that the proximity effects between Co and Pt with perpendicular magnetic anisotropy can be prevented by the insertion of a Cu layer with a nominal threshold thickness of 0.7 nm. Element-specific magnetization curves were also obtained, demonstrating that the out-of-plane magnetization is induced in the Cu layers of the Co/Cu/Pt structures.

More stable and reliable pharmacokinetics with preprandial administration of cyclosporine compared with postprandial administration in patients with refractory nephrotic syndrome.

STUDY OBJECTIVE: To compare the absorption profile of cyclosporine after preprandial administration with that after postprandial administration, and to determine which administration time resulted in a more stable absorption profile and the timing of the drug concentration that was the most reliable marker for monitoring drug absorption. DESIGN: Prospective analysis. SETTING: University teaching hospital in Japan. PATIENTS: Sixteen patients with refractory nephrotic syndrome. INTERVENTION: Thirteen patients received cyclosporine after breakfast (postprandial group) and eight received the drug 30 minutes before breakfast (preprandial group). MEASUREMENTS AND MAIN RESULTS: Blood cyclosporine concentration was measured 5 times serially: before administration (C 0 ) and at 1-hour intervals until 4 hours after administration of cyclosporine (C 1 -C 4 ). Also, area under the concentration-time curve from 0-4 hours (AUC 0-4 ) was calculated. Of the 13 patients in the postprandial group, six (46%) showed fair absorption and exhibited a peak concentration at C 1 or C 2 (high-absorption pattern); seven (54%) showed poor absorption and did not reach the peak concentration within the 4-hour period (low-absorption pattern). Five of the seven patients with the low-absorption pattern were switched from postprandial to preprandial administration. All patients in the preprandial administration group showed a high-absorption pattern and reached the peak cyclosporine concentration at C 1 . The C 2 value showed the best correlation with AUC 0-4 in both groups, and the C 0 parameter did not correlate with AUC 0-4 in either group. CONCLUSION: Preprandial administration provided a more stable absorption profile of cyclosporine compared with postprandial administration. From the correlation with AUC 0-4 , we concluded that C 2 , and not C 0 , is a reliable marker for monitoring cyclosporine exposure.

[Takotsubo cardiomyopathy thought to be induced by MRSA meningitis and cervical epidural abscess in a maintenance-hemodialysis patient: case report].

A 65-year-old man was admitted to our hospital for high fever and severe left shoulder pain. He was initiated on maintenance hemodialysis for end-stage renal failure caused by diabetic nephropathy 9 years previously. On admission, the serum CRP level was 29.3 mg/d/l and the white blood cell count was 29,000/mm3. Bacterial examination of blood and spinal fluid revealed MRSA colonization. On the 6th hospital day, a giant negative T wave in the V2-6 leads of an electrocardiogram asymptomatically appeared. Ultracardiogram revealed apical systolic paradoxical centrifugal motion. None of the cardiogenic enzymes, such as creatine kinase, lactate dehydrogenase and glutamic oxaloacetic transaminase was elevated. Cardiac thallium-201-chloride (201Tl-Cl) and I-123 beta-metyl iodophenyl-pentadecanoic acid (123I-BMIPP) scintigraphy revealed a decreased accumulation of isotopes in the apex. From these findings, we diagnosed Takotsubo cardiomyopathy induced by MRSA meningitis. Vancomycin was administrated and the inflammatory signs decreased. On the 46th hospital day, tetraplegia and respiratory suppression occurred. A cervical spinal magnetic resonance image revealed cervical spondylodiscitis and cervical epidural abscess, which compressed the medulla oblongata. Surgical spinal decompression and drainage of the abscess were performed. The giant negative T wave in the electrocardiogram improved after the operation. Two months after the operation, cardiac 201Tl-Cl scintigraphy revealed improvement in the accumulation of isotopes in the apex. Takotsubo cardiomyopathy is secondary cardiomyopathy presenting with apical systolic paradoxical centrifugal motion without coronary stenotic disease. It has been reported to be induced by severe mental stress or intracranial disease. In the present patient, it was predicted that stress on the central nerve system caused by the MRSA meningitis and the cervical epidural abscess induced the Takotsubo cardiomyopathy.

Bis(acetylacetonato)bis(pyrazolato)ruthenate(iii) as a redox-active scorpionate ligand.

The potential of a new anionic octahedral metal complex [Ru(III)(acac)2(pz)2](-) ((-)) (pzH = pyrazole) as a ligand with a scorpionate coordination behaviour like tris(pyrazolyl)borate (tp) and reversible redox activity is presented. Trinuclear metal complexes, [Ru(III)2Zn(II)(acac)4(pz)4] () and [Ru(II)Ru(III)2(acac)4(pz)4] (), were each synthesized by the reaction of ZnCl2 or Ru3(CO)12 with [Ru(III)(acac)2(pz)(pzH)] (H) that is in situ deprotonated and acts as a precursor of (-). Single-crystal X-ray diffraction studies clarified that (-) acts as a scorpionate ligand; two (-) units in and one unit in function as bidentate ligands with two pyrazolates as pincers, while another (-) unit in functions as a tridentate ligand with one oxygen atom as a tail in addition to the two pyrazolate pincers. Moreover, and showed reversible multi-stage redox behaviours based on the Ru(II)/Ru(III) and Ru(III)/Ru(IV) couples of the (-) units in the cyclic voltammetry (CV) measurements. Based on the X-ray, IR, and CV measurements and the comparison with other Ru(ii) complexes with tp derivatives, the (-) unit was found to act as a redox-active scorpionate with electron withdrawing properties compared to the tp.