Complexation of small molecules by open-ended resorcarene hosts

[structure: see text] Sterically hindered tetraaminomethylated resorcarenes form inclusion complexes in CDCl(3) with acetonitrile and acetaldehyde, which are kinetically stable on the NMR time scale at 233 K.     

Phase separation and anisotropy in the electrical properties of weakly doped lanthanum manganites

Variations in the thermopower, electrical resistivity, magnetoresistance, thermal expansion coefficients, and their anisotropy with temperature were detected near room temperature in single crystals of weakly doped lanthanum manganites La_1?xA_xMnO₃ (A = Ca, Sr; x = 0.07–0.125) with orthorhombic structure. The results obtained are discussed in terms of a model of phase separation related to polaron anisotropy. Due to a gain in exchange and elastic energies in the lattice, small-radius magnetic polarons can merge to form polarons of a larger size, which would contain now not one but rather a few electrons (equal in number to the polarons in the cluster). As a result, short-range order in a cluster and phase separation set in at a temperature T_ps ≈ 250–300 K, which is approximately equal to the Curie temperature T_C of conducting manganites with x ≈ 0.2–0.3.     

Thermal electron capture by some chlorobromopropanes

Thermal electron attachment rate constants for CH₂ClCHBrCH₃ and CH₂ClCH₂CH₂Br have been measured using electron swarm method. Corresponding rate constants are equal to 3.5×10^-10 and 2.5×10^-10 cm³ molec^-1 s^-1, respectively. Parallely, negative ion mass spectra of these compounds as well as CH₂FCH₂Br, CH₂ClCH₂Br, CH₂BrCH₂Br and CF₃CHClBr has been measured with negative ion mass spectrometry method. The rate constants have been compared with the negative ion mass spectra.     

Coxeter groups A4, B4 and D4 for two-qubit systems

The Coxeter–Weyl groups W(A₄), W(B₄), and W(D₄) have proven very useful for two-qubit systems in quantum information theory. A simple technique is employed to construct the unitary matrix representations of the groups, based on quaternionic transformation of the usual reflection matrices. The von Neumann entropy of each reduced density matrix is calculated. It is shown that these unitary matrix representations are naturally related to various universal quantum gates and they lead to entangled states. Canonical decomposition of generators in terms of fundamental gate representations is given to construct the quantum circuits.     

Nanostructuring of 1-butyl-4-methylpyridinium chloride in ionic liquid–iron oxide nanofluids

Journal of Thermal Analysis and Calorimetry - Understanding the behavior of ionic liquids (ILs) in ionic liquid-based nanofluids has great significance for its proper application. The phase changes...     

Highly Bright White Organic Light-Emitting Diode

A highly bright white organic light-emitting diode (OLED) was realized by using a highly bright blue emitting layer, 1,7-diphenyl-4-biphenyl-3,5-dimethyl-l,7-dihydrodipyrazolo[3,4-b;4',3'-e]pyridine (PAP-Ph), together with a 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM)-doped Alq [tris(8-hydroxyquinolinato) aluminum (Ⅲ)] layer to provide the blue, red and green emission for color mixing. With appropriate thickness control, the white-light OLED has a performance that reaches 24700 cd/m2 at 15 V, 1.93 lm/W at 6.5 V, and ＞300 cd/m2 at 7.7 mA/em2. The Commission Internationale de l'Eclairage (CIE) coordinates of the emitted light vary in a very small range, from (0.35, 0.34) to (0.34, 0.35), when forward voltages change from 6 to 12 V.     

Strong and weak modes in polytypes of SiC

The concept of an extended Brillouin zone is used to analyze the intensity of phonon modes observed in optical and Raman investigations of different polytypes of silicon carbide. It is shown that the relative intensity of these modes agrees with the magnitude of the splitting of the doublets, which are degenerate in the extended zone. Pis’ma Zh. éksp. Teor. Fiz. 69, No. 3, 247–250 (10 February 1999)     

Transition radiation of a charge in media with a nonuniform potential

The influence of a potential barrier on the transition radiation in the form of volume and surface electromagnetic waves emitted by a charged particle crossing an interface between media is investigated. It is shown that the volume-wave radiation field arises not only as a result of the jump in the dielectric constant at the boundary but also as a result of the velocity jump and the reflection of an electron induced by the presence of a nonuniform potential barrier. The angular distribution of the transition radiation intensity is obtained. Zh. Tekh. Fiz. 68, 11–14 (January 1998)     

RANDOM RESPONSE OF PREISACH HYSTERETIC SYSTEMS

An approximate method for analyzing the response of Preisach hysteretic systems with non-local memory under stationary Gaussian excitation is proposed. The covariance matrix equation of system response is derived. The cross correlation function of Preisach hysteretic force and response in the covariance equation is evaluated based on the switching probability analysis and the Gaussian approximation of response process and an explicit expression for the cross correlation function is given for the case of symmetric Preisach weighting function. It is shown that the numerical result obtained by using the proposed method is in good agreement with that from digital simulation.