Strong correlation effects and new phase transition at high pressure-low temperature in La0.5Ba0.5FeO3

The physical properties of La_0.5Ba_0.5FeO₃ perovskite have been investigated. The resistivity and magnetism change at around the charge disproportionation temperature. The ferromagnetic cluster-glass state appears when . Under 5 kbar pressure a new phase transition at 5.5 K is found in the magnetization measurement. The transition temperature increases with the increase of the applied pressure. It is suggested that this transition is induced by the spin state transition from to with the pressure increase.     

On the Characterization of Maximal Planar Graphs with a Given Signed Cycle Domination Number

Let G =(V, E) be a simple graph. A function f : E → {+1,-1} is called a signed cycle domination function(SCDF) of G if ∑_(e∈E(C))f(e) ≥ 1 for every induced cycle C of G. The signed cycle domination number of G is defined as γ'_(sc)(G) = min{∑_(e∈E)f(e)| f is an SCDF of G}. This paper will characterize all maximal planar graphs G with order n ≥ 6 and γ'_(sc)(G) = n.     

Energy levels and their correlations in quasicrystals

Quasicrystals can be considered, from the point of view of their electronic properties, as being intermediate between metals and insulators. For example, experiments show that quasicrystalline alloys such as AlCuFe or AlPdMn have conductivities far smaller than those of the metals that these alloys are composed from. Wavefunctions in a quasicrystal are typically intermediate in character between the extended states of a crystal and the exponentially localized states in the insulating phase, and this is also reflected in the energy spectrum and the density of states. In the theoretical studies we consider in this review, the quasicrystals are described by a pure hopping tight binding model on simple tilings. We focus on spectral properties, which we compare with those of other complex systems, in particular, the Anderson model of a disordered metal. We discuss ‘strong‘ and ‘weak’ quasicrystals, which are described by different universal laws. We find similarities and universal behaviour, but also significant differences between quasiperiodic models and models with disorder. Like weakly disordered metals, the quasicrystal can be described by the universal level statistics that can be derived from random matrix theory. These level statistics are only one aspect of the energy spectrum, whose very large fluctuations can also be described by a level spacing distribution that is log-normal. An analysis of spectral rigidity shows that electrons diffuse with a bigger exponent (super-diffusion) than in a disordered metal. Adding disorder attenuates the singular properties of the perfect quasicrystal, and leads to improved transport. Spectral properties are also used in computing conductances of such systems, and to attempt to resolve the experimental enigmas such as whether quasicrystals are intrinsically conductors, and if so, how conductances depend on the structure.     

Indeno[1,2‐b]fluorene‐Based [2,2]Cyclophanes with 4n/4n and 4n/[4n+2] π Electrons: Syntheses,Structural Analyses,and Excitonic Coupling Properties

Indeno[1,2‐b]fluorene‐based [2,2]cyclophanes with 4n/4n and 4n/[4n+2] π‐electron systems were prepared, and their structures were identified by X‐ray crystallography. With short π–π distances around 3.0 Å, [2.2](5,11)indeno[1,2‐b]fluorenophane and its precursor [2.2](5,11)indeno[1,2‐b]fluorene‐6,12‐dionophane exhibit remarkable transannular interactions, leading to their unusual electrochemical and photophysical properties. With the aid of femtosecond transient absorption spectroscopy, the transition from the monomeric excited state to the redshifted H‐type dimeric state was first observed, correlating to the calculated excitonic energy splitting and the steady‐state absorption spectra induced by charge‐transfer‐mediated superexchange interaction.     

Novel optical orthogonally modulation scheme for superimposing DPSK signals on dark RZ signals

A configuration of transmitter for superimposing DPSK signals on dark RZ signals was proposed. The transmitter comprises two optical phase modulators and a delayed line Mach-Zehnder interferometer. A new orthogonally modulation format with tunable duty cycle and extinction ratio in the optical domain was generated and discussed. The results show that the proposed modulation format offers significant advantages in offering high spectral efficiency values, high extinction ratio, and requiring electronics with reduced bandwidth.     

One Terminal Guanosine Flip of Intramolecular Parallel G-Quadruplex: Catalytic Enhancement of G-Quadruplex/Hemin DNAzymes

Numerous studies have shown compelling evidence that incorporation of an inversion of polarity site (IPS) in G-rich sequences can affect the topological and structural characteristics of G-quadruplexes (G4s). Herein, the influence of IPS on the formation of a previously studied intramolecular parallel G4 of d(G₃TG₃TG₃TG₃) (TTT) and its stacked higher-order structures is explored. Insertion of 3′–3′ or 5′–5′ IPS did not change the parallel folding pattern of TTT. However, both the species and position of the IPS in TTT have a significant impact on the G4 stability and end-stacking through the alteration of G4–G4 interfaces properties. The data demonstrate that one base flip in each terminal G-tetrad can stabilize parallel G4s and facilitate intermolecular packing of monomeric G4s. Such modifications can also enhance the fluorescence and enzymatic performances by promoting interactions between parallel G4s with N-methyl mesoporphyrin IX (NMM) and hemin, respectively.