129 research outputs found
Observation of oscillatory relaxation in the Sn-terminated surface of epitaxial rock-salt SnSe topological crystalline insulator
Topological crystalline insulators have been recently predicted and observed
in rock-salt structure SnSe thin films. Previous studies have
suggested that the Se-terminated surface of this thin film with hydrogen
passivation, has a reduced surface energy and is thus a preferred
configuration. In this paper, synchrotron-based angle-resolved photoemission
spectroscopy, along with density functional theory calculations, are used to
demonstrate conclusively that a rock-salt SnSe thin film
epitaxially-grown on \ce{Bi2Se3} has a stable Sn-terminated surface. These
observations are supported by low energy electron diffraction (LEED)
intensity-voltage measurements and dynamical LEED calculations, which further
show that the Sn-terminated SnSe thin film has undergone a surface
structural relaxation of the interlayer spacing between the Sn and Se atomic
planes. In sharp contrast to the Se-terminated counterpart, the observed Dirac
surface state in the Sn-terminated SnSe thin film is shown to yield a
high Fermi velocity, m/s, which suggests a potential mechanism
of engineering the Dirac surface state of topological materials by tuning the
surface configuration.Comment: 12 pages, 13 figures, supplementary materials include
Regional metabolic patterns of abnormal postoperative behavioral performance in aged mice assessed by 1H-NMR dynamic mapping method
Abstract
Abnormal postoperative neurobehavioral performance (APNP) is a common phenomenon in the early postoperative period. The disturbed homeostatic status of metabolites in the brain after anesthesia and surgery might make a significant contribution to APNP. The dynamic changes of metabolites in different brain regions after anesthesia and surgery, as well as their potential association with APNP are still not well understood. Here, we used a battery of behavioral tests to assess the effects of laparotomy under isoflurane anesthesia in aged mice, and investigated the metabolites in 12 different sub-regions of the brain at different time points using proton nuclear magnetic resonance (1H-NMR) spectroscopy. The abnormal neurobehavioral performance occurred at 6 h and/or 9 h, and recovered at 24 h after anesthesia/surgery. Compared with the control group, the altered metabolite of the model group at 6 h was aspartate (Asp), and the difference was mainly displayed in the cortex; while significant changes at 9 h occurred predominantly in the cortex and hippocampus, and the corresponding metabolites were Asp and glutamate (Glu). All changes returned to baseline at 24 h. The altered metabolic changes could have occurred as a result of the acute APNP, and the metabolites Asp and Glu in the cortex and hippocampus could provide preliminary evidence for understanding the APNP process
ЕВОЛЮЦІЯ МЕТОДОЛОГІЧНИХ ЗАСАД ДОСЛІДЖЕННЯ НОВОЇ ЕКОНОМІКИ: ВІД СТОХАСТИЧНОЇ ПЕРЦЕПЦІЇ ДО АЛГОРИТМІЗАЦІЇ ПІЗНАННЯ
Структуровані основні методологічні підходи до організації фундаментальних досліджень динаміки нової економіки; парадигма глобального еволюці-онізму визначена як найбільш адекватної та гносеологічно перспективної методологічної основи таких досліджень. Сучасна версія глобального еволюціонізму розглядається як результат інтеграції системного підходу, синергетики і еволюціонізму.; The basic methodological approaches to organization of fundamental researches of dynamics of new economy are considered and structured; the paradigm of global evolutionism is determined as the most adequate and agnostically perspective methodological basis of similar researches. The modern version of global evolutionism is examined as a result of integration of system approach, synergetic and evolutionism
Global transcriptional analysis of nitrogen fixation and ammonium repression in root-associated Pseudomonas stutzeri A1501
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