Nature creates beautiful structural colors, and some of these colors are produced by nanostructural arrays of melanin. Polydopamine (PDA), an artificial black polymer produced by self-oxidative polymerization of dopamine, has attracted extensive attention because of its unique properties. PDA is a melanin-like material, and recent studies have reported that photonic materials based on PDA particles showed structural colors by enhancing color saturation through the absorption of scattered light. Herein, we describe the preparation of three-dimensional (3D) colloidal photonic materials, such as structural color balls and fibers, from biomimetic core-shell particles with melanin-like PDA shell layers. Structural color balls were prepared through the combined use of membrane emulsion and heating. We also demonstrated the use of microfluidic emulsification and solvent diffusion for the fabrication of structural color fibers. The obtained 3D colloidal materials, i.e., balls and fibers, exhibited angle-independent structural colors due to the amorphous assembly of PDA-containing particles. These findings provide new insight for the development of dye-free technology for the coloration of various 3D colloidal architectures.
Cobalt(II), nickel(II), and copper(II) complexes with dioximes substituted by BF2- and B(C2H5)2-groups for bridging hydrogen atoms were prepared. The BF2-substitution caused a red-shift of d-d band and increase of g⁄⁄-value for copper(II) complexes and positive shift of polarographic half wave potential of nickel(II) complexes. In the case of the B(C2H5)2-substituted complexes, such variations were not observed. The BF2-substituted cobalt(II) complexes are stable under an open atmosphere at room temperature in a solid state and in a DMF solution. These were interpreted in terms of the electron-withdrawing ability of BF2-group in the ligand.
Background Several anesthetic agents are used in cesarean sections for both regional and general anesthesia purposes. However, there are no data comparing the in vivo effects of propofol, sevoflurane, and dexmedetomidine on the contraction of the myometrium in pregnant rats. The aim of this study was to investigate the effect of these anesthetic agents on myometrial contraction and elucidate the underlying mechanisms. Methods Contraction force and frequency changes in response to propofol, dexmedetomidine, or sevoflurane were evaluated in vivo and in vitro. To test the effect of arachidonic acid on myometrial contraction enhanced by dexmedetomidine, changes in myometrial contraction with dexmedetomidine after administration of indomethacin were evaluated. The amount of phosphorylated myosin phosphatase target subunit 1 (MYPT1) in the membrane fraction was expressed as a percentage of the total fraction by Western blot analysis. Results This study demonstrated that dexmedetomidine enhances oxytocin-induced contraction in the myometrium of pregnant rats, whereas propofol and sevoflurane attenuate these contractions. The dexmedetomidine-induced enhancement of myometrial contraction force was abolished by the administration of indomethacin. Propofol did not affect oxytocin-induced MYPT1 phosphorylation, whereas sevoflurane attenuated oxytocin-induced MYPT1 phosphorylation. Conclusions Inhibition of myofilament calcium sensitivity may underlie the inhibition of myometrial contraction induced by sevoflurane. Arachidonic acid may play an important role in the enhancement of myometrial contraction induced by dexmedetomidine by increasing myofilament calcium sensitivity. Dexmedetomidine may be used as a sedative agent to promote uterine muscle contraction and suppress bleeding after fetal delivery.
We comparatively study the excitonic insulator state in the extended Falicov-Kimball model (EFKM, a spinless two-band model) on the two-dimensional square lattice using the variational cluster approximation (VCA) and the cluster dynamical impurity approximation (CDIA). In the latter, the particle-bath sites are included in the reference cluster to take into account the particle-number fluctuations in the correlation sites. We thus calculate the particle-number distribution, order parameter, ground-state phase diagram, anomalous Green's function, and pair coherence length, thereby demonstrating the usefulness of the CDIA in the discussion of the excitonic condensation in the EFKM. IntroductionThe excitonic phases, often referred to as excitonic insulators (EIs), are the states where the valence and conduction bands are hybridized spontaneously by the interband Coulomb interaction, and have been predicted to occur near the semimetal-semiconductor phase boundary as the quantum condensation of electron-hole pairs (excitons). [1][2][3][4][5][6] In the semimetallic region, where the Coulomb interaction is largely screened by free carriers, the excitonic phase is described in analogy to the BCS theory of superconductivity, whereas in the semiconducting region, it is described as the Bose-Einstein condensation (BEC) of preformed excitons (or strongly bound electron-hole pairs). Thus, the BCS-BEC crossover is expected to occur by controlling the band gap from a negative value to a positive one. [7][8][9] In recent years, the possible realization of spinsinglet excitonic condensation has been suggested for transition-metal chalcogenides such as 1T -TiSe 2 and Ta 2 NiSe 5 . 10-23) The spin-triplet excitonic condensation has also been suggested to occur in the high-spin/lowspin crossover region of some cobalt oxide materials with the cubic perovskite structure. 24-29) Because these materials are among transition-metal chalcogenides and oxides, where the effects of electron correlations are strong, one must reconsider the excitonic phases from the standpoint of strongly correlated electron systems. 30-32) Thus, the lattice models such as Hubbard models, rather than the gas models, are appropriate for use. The spinless extended Falicov-Kimball model (EFKM) is the simplest lattice model for describing the excitonic phases, and has been used to discuss, for example, the BCS-BEC crossover of the excitonic condensation. 33-41) The multiband Hubbard model, taking into account the spin de-
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