Synthesis of chiral N-heterocyclic carbene ligands with rigid backbones and application to the palladium-catalyzed enantioselective intramolecular α-arylation of amides

Chiral N-heterocyclic carbene (NHC) ligands having a 2,2'-bisquinoline-based C(2) symmetric skeleton were developed. The ligands exhibited good enantioselectivity in palladium-catalyzed intramolecular α-arylation of amides to give 3,3-disubsituted oxindoles.     

Randomized strategy equilibrium in the action commitment game with costs of leading

We investigate a two-player action commitment game where one simultaneous-move and two sequential-move pure strategy equilibria exist when the cost of leading is zero, while the simultaneous-move outcome is not an equilibrium when the leading cost is small positive. We show that this discontinuity disappears if we consider randomized strategy equilibria. We investigate a price competition model and show that randomized strategy equilibria exist and any of them converges to the Bertrand equilibrium when the leading cost converges to zero.     

Colorful Strips

We study the following geometric hypergraph coloring problem: given a planar point set and an integer k, we wish to color the points with k colors so that any axis-aligned strip containing sufficiently many points contains all colors. We show that if the strip contains at least 2k − 1 points, such a coloring can always be found. In dimension d, we show that the same holds provided the strip contains at least k(4 ln k + ln d) points. We also consider the dual problem of coloring a given set of axis-aligned strips so that any sufficiently covered point in the plane is covered by k colors. We show that in dimension d the required coverage is at most d(k − 1) + 1. This complements recent impossibility results on decomposition of strip coverings with arbitrary orientations. From the computational point of view, we show that deciding whether a three-dimensional point set can be 2-colored so that any strip containing at least three points contains both colors is NP-complete. This shows a big contrast with the planar case, for which this decision problem is easy.     

Relativistic chiral mean field model for finite nuclei

We present a method for proper treatment of pion-exchange interaction in the nuclear many-body problem in a relativistic chiral mean field (RCMF) model. The pionic correlation is expressed in 2-particle 2-hole (2p–2h) states in addition to the standard mean field state, to describe the full strength of pionic correlations. The effect of the short-range repulsion is included by way of the unitary correlation operator method (UCOM) for the central part of the pion-exchange interaction. We apply the RCMF model to ¹²C and ¹⁶O. The convergence of pionic energy contributions is realized with pionic quantum number Jπ$J^{\pi }$ up to 10⁻ for ¹²C and 11⁺ for ¹⁶O. The pion-exchange interaction gives the dominant contribution to the binding energy. The pion plays an important role in the formation of the jj  -magic shell effect by way of the Pauli-blocking mechanism of the pion-exchange interaction. The lower pionic quantum numbers Jπ?³⁺$J^{\pi }?3^{+}$ are the dominant components of the nuclear surface structure.     

Cooperative Regulation of Vocal Fold Morphology and Stress by the Cricothyroid and Thyroarytenoid Muscles

Voice is produced by vibrations of vocal folds that consist of multiple layers. The portion of the vocal fold tissue that vibrates varies depending primarily on laryngeal muscle activity. The effective depth of tissue vibration should significantly influence the vibrational behavior of the tissue and resulting voice quality. However, thus far, the effect of the activation of individual muscles on the effective depth is not well understood. In this study, a three-dimensional finite element analysis is performed to investigate the effect of the activation of two major laryngeal muscles, the cricothyroid (CT) and thyroarytenoid (TA) muscles, on vocal fold morphology and stress distribution in the tissue. Because structures that bear less stress can easily be deformed and involved in vibration, information on the morphology and stress distribution may provide a useful estimate of the effective depth. The results of the analyses indicate that the two muscles perform distinct roles, which allow cooperative control of the morphology and stress. When the CT muscle is activated, the tip region of the vocal folds becomes thinner and curves upward, resulting in the elevation of the stress magnitude all over the tissue to a certain degree that depends on the stiffness of each layer. On the other hand, the TA muscle acts to suppress the morphological change and controls the stress magnitude in a position-dependent manner. Thus, the present analyses demonstrate quantitative relationships between the two muscles in their cooperative regulation of vocal fold morphology and stress.     

Influence of Ar background gas pressure on composition and crystal orientation in PLD-Fe(Se1−xTex) thin films

Fe(Se_1?xTe_x) thin films on (1 0 0) SrTiO₃ were fabricated by a pulsed laser deposition method, and their crystal orientation, compositional shifts and superconducting properties were characterized by X-ray diffraction, scanning electron microscope combined with energy dispersive X-ray spectroscopy, etc. Compositional shift is one of the major problems during the fabrication of Fe(Se_1?xTe_x) films due to its containing high volatile elements such as Se and Te. The compositional shifts were found dependent on the Ar background gas pressure (P_Ar), which was suppressed by the increase of P_Ar. In addition, it was revealed that the temperature window for the crystallization of the films was shifted to higher temperature region and wider temperature range with the increase of P_Ar.     

Novel heterotetranuclear V2Mo2 or V2W2 complexes with 4,4'-di-tert-butyl-2,2'-bipyridine: syntheses, crystal structures, and catalytic activities

Two novel heterotetranuclear complexes [V(2)O(2)(μ-MeO)(2)(μ-WO(4))(2)(4,4'-(t)Bubpy)(2)] (1) and [V(2)O(2)(μ-MeO)(2)(μ-MoO(4))(2)(4,4'-(t)Bubpy)(2)] (2) were synthesized, and the solid state structures of these complexes were revealed by single crystal X-ray crystallography. The heterotetranuclear complexes 1 and 2 are centrosymmetric building blocks, considered as consisting of two [VO(4,4'-(t)Bubpy)](3+) units bridged by μ-MO(4)(2-) (M = W or Mo) anions connected with methoxy groups. Furthermore, catalytic activities of 1 and 2 in the alcohol oxidation with hydrogen peroxide as terminal oxidants in water as solvent were investigated.     

Synthesis of 2,4-diiodoquinolines via the photochemical cyclization of o-alkynylaryl isocyanides with iodine

Upon photoirradiation of o-alkynylaryl isocyanides in the presence of iodine, the intramolecular cyclization of o-alkynylaryl isocyanides proceeds to afford the corresponding 2,4-diiodoquinolines in good yields. 2,4-Diiodoquinolines can be employed in transition metal-catalyzed cross-coupling reactions.     

Photosensitization reaction-induced acute electrophysiological cell response of rat myocardial cells in short loading periods of talaporfin sodium or porfimer sodium

Electrophysiological responses of rat myocardial cells to exogenous photosensitization reactions for a short period of incubation with two photosensitizers, talaporfin sodium or porfimer sodium, were measured in a subsecond time scale. The loading period of the photosensitizer when the photosensitizer might not be taken up by the cells was selected as 15min, which was determined by the fluorescence microscopic observation. We measured the intracellular Ca(2+) concentration ([Ca(2+) ](in) ) by using a fluorescent Ca(2+) indicator, Fluo-4 AM, under a high-speed confocal laser microscope to evaluate the acute electrophysiological cell response to the photosensitization reaction. The measured temporal change in Fluo-4 fluorescence intensity indicated that the response to the photosensitization reaction might be divided into two phases in both photosensitizers. The first phase is acute response: disappearance of Ca(2+) oscillation when irradiation starts, which might be caused by ion channel dysfunction. The second phase is slow response: [Ca(2+) ](in) elevation indicating influx of Ca(2+) due to the concentration gradient. The continuous Ca(2+) influx followed by changes in cell morphology suggested micropore formation on the surface of the cell membrane, resulting in necrotic cell death.     

IrCl3 or FeCl3-catalyzed convenient synthesis of 3-hydroxyphthalates

IrCl₃·3H₂O or FeCl₃-catalyzed convenient synthesis of 3-hydroxyphthalates has been achieved by a Diels-Alder reaction of furans with dimethyl acetylenedicarboxylate, followed by ring-opening aromatization reaction of the Diels-Alder adducts, 7-oxabicyclo[2.2.1]hepta-2,5-diene derivatives. In addition, 7-azabicyclo[2.2.1]hepta-2,5-diene derivative, derived from N-Boc-pyrrole and dimethyl acetylenedicarboxylate, also converted into 3-aminophthalate derivative.