Molecular Dynamics Study of the Formation of Solid Al–C Nanocomposites

Migration of graphene fragments along the aluminum matrix in the solid phase was studied by molecular dynamics. The structure of the Al–C nanocomposite grain was studied by statistical geometry. The distributions of the topological and metric characteristics of truncated polyhedra were calculated for the Al subsystem; the distributions for the polyhedra constructed at the centers of mass of the hypothetical geometrical neighbors were calculated for the carbon subsystem. The graphene fragments are concentrated at the structural grain boundaries. The nanocomposite grains are preferably separated by single-layer graphene rather than by the two-layer graphene membrane.     

Infrared spectroscopy of 17O- and 18O-enriched carbon dioxide in the 1700–8300 cm−1 wavenumber region

The assignment of the high resolution Fourier transform spectra of carbon dioxide enriched in ¹⁷O and ¹⁸O which were recorded in LADIR (Paris, France) with the Bruker IFS 125-HR between 1800 and 9000 cm^?1 and in USTC (Hefei, China) with the Bruker IFS 120-HR between 1700 and 9000 cm^?1 was performed. In total 239 bands of 12 isotopologues: ¹⁶O¹²C¹⁶O, ¹⁶O¹²C¹⁸O, ¹⁶O¹³C¹⁶O, ¹⁶O¹³C¹⁸O, ¹⁸O¹²C¹⁸O, ¹⁸O¹³C¹⁸O, ¹⁶O¹²C¹⁷O, ¹⁷O¹²C¹⁷O, ¹⁷O¹²C¹⁸O, ¹⁶O¹³C¹⁷O, ¹⁷O¹³C¹⁷O and ¹⁷O¹³C¹⁸O were observed. Among them, 99 bands were observed for the first time. The majority of new observed bands belong to ¹⁷OCO isotopologues. The positions of 23,003 lines were determined with the experimental uncertainty on the level of 0.001 cm^?1. The spectroscopic constants were fitted to the observed line positions for all observed bands.     

Wave Resonance in Media with Modular,Quadratic and Quadratically-Cubic Nonlinearities Described by Inhomogeneous Burgers-Type Equations

The phenomenon of “wave resonance” which occurs at excitation of traveling waves in dissipative media possessing modular, quadratic and quadratically-cubic nonlinearities is studied. The mathematical model of this phenomenon is the inhomogeneous (or “forced”) equation of Burgers type. Such nonlinearities are of interest because the corresponding equations admit exact linearization and describe real physical objects. The presence of “accompanying sources” (traveling with the wave) on the right-hand side of the inhomogeneous equations ensures the inflow of energy into the wave, which thereafter spreads throughout the wave profile, flows to emerging shock fronts, and then dissipates due to linear and nonlinear losses. As an introduction, the phenomenon of wave resonance in ideal and dissipative media is described and physical examples are given. Exact expressions for nonlinear steady-state wave profiles are derived. Non-stationary processes of wave generation, spatial “beating” of amplitudes with different relationship between the speed of motion of the sources and the natural wave velocity in the medium are studied. Resonance curves are constructed that contain a nonlinear shift of the absolute maxima to the “supersonic” region. The features of the resonance in each of the three types of nonlinearity are discussed.     

Functionalization of (<Emphasis Type="Italic">n</Emphasis>, 0) CNTs (<Emphasis Type="Italic">n</Emphasis> = 3–16) by uracil: DFT studies

Density functional theory (DFT) calculations were performed to investigate stabilities and properties for uracil (U)-functionalized carbon nanotubes (CNTs). To this aim, the optimized molecular properties were evaluated for (n, 0) models of CNTs (n = 3–16) in the original and U-functionalized forms. The results indicated that the dipole moments and energy gaps were independent of tubular diameters whereas the binding energies showed that the U-functionalization could be better achieved for n = 8–11 curvatures of (n, 0) CNTs. Further studies based on the evaluated atomic-scale properties, including quadrupole coupling constants (C _Q ), indicated that the electronic properties of atoms could detect the effects of diameters variations of (n, 0) CNTs, in which the effects were very much significant for the atoms around the U-functionalization regions. Finally, the achieved results of singular U, original CNTs, and CNT-U hybrids were compared to each other to demonstrate the stabilities and properties for the U-functionalized (n, 0) CNTs.     

Critical and multicritical behavior in the Ising–Heisenberg universality class

Critical behavior of three-dimensional classical frustrated antiferromagnets with a collinear spin ordering and with an additional twofold degeneracy of the ground state is studied. We consider two lattice models, whose continuous limit describes a single phase transition with a symmetry class differing from the class of non-frustrated magnets as well as from the classes of magnets with non-collinear spin ordering. A symmetry breaking is described by a pair of independent order parameters, which are similar to order parameters of the Ising and O(N) models correspondingly. Using the renormalization group method, it is shown that a transition is of first order for non-Ising spins. For Ising spins, a second order phase transition from the universality class of the O(2) model may be observed. The lattice models are considered by Monte Carlo simulations based on the Wang–Landau algorithm. The models are a ferromagnet on a body-centered cubic lattice with the additional antiferromagnetic exchange interaction between next-nearest-neighbor spins and an antiferromagnet on a simple cubic lattice with the additional interaction in layers. We consider the cases N = 1, 2, 3 and in all of them find a first-order transition. For the N = 1 case we exclude possibilities of the second order or pseudo-first order of a transition. An almost second order transition for large N is also discussed.     

Highly stable inverted poly (3-hexylthiophene):methano-fullerene [6,6]-phenyl C71-butyric acid methyl ester bulk heterojunction solar cell with thin oxide nano particle layer using solution process

We have investigated the inverted poly (3-hexylthiophene):methano-fullerene [6,6]-phenyl C71-butyric acid methyl ester (P3HT:PC₇₁BM) bulk heterojunction (IBHJ) solar cell with various n-type metal oxide nano particle layers on ITO and MoO₃ anode buffer layer underneath Al. The IBHJ solar cell with a tin oxide nano particle layer shows the power conversion efficiency (PCE) of 3.1% and better stability compared to conventional BHJ solar cell. The PCE of this cell decreases by 3% after 2 months in ambient air while the other cells show more degradation.     

X-ray magneto-optics of lanthanide materials: principles and applications

Lanthanide metals are a particular class of magnetic materials in which the magnetic moments are carried mainly by the localized electrons of the 4f shell. They are frequently found in technically relevant systems, to achieve, e.g., high magnetic anisotropy. Magneto-optical methods in the X-ray range are well suited to study complex magnetic materials in an element-specific way. In this work, we report on recent progress on the quantitative determination of magneto-optical constants of several lanthanides in the soft X-ray region and we show some examples of applications of magneto-optics to hard-magnetic interfaces and exchange-coupled layered structures containing lanthanide elements. PACS 78.20.Ls; 78.70.Dm; 78.70.Ck; 78.20.Ci; 75.70.-i     

D = 5, N = 2 Geometric Higher Curvature Supergravity in the Second-Order Canonical Theory

The supersymmetric extension of the five-dimensional Chern–Simons gravity is studied from the Hamiltonian point of view. This model containing the Gauss–Bonnet term quadratic in the Riemann curvature is the gauge theory of the supergroup SU(2,2/1). In the first order, the theory has a polynomial structure, but the second-order leads to a nonpolynomial structure for both the Hamiltonian and the supersymmetry transformation rules of the fields. The second-order theory has the advantage that the apparent gauge degrees of freedom are unambiguously removed leaving only the physical ones. This important feature is analyzed by constructing the second-order Hamiltonian theory. The gauge invariances of the model and the generator of time evolution are found.     

Optical properties of excimers in the field of intense laser radiation

The specific features of the luminescence of excimer molecules are analyzed within the model of a purely repulsive potential for the ground state in the field of intense laser radiation with due regard for the squeezed vibrational states. It is demonstrated that the luminescence band with the inclusion of the equilibrium phonons can be represented by a broad structureless asymmetric bell-shaped curve. The squeezed vibrational states substantially affect the frequency dependence of the luminescence intensity; more specifically, the luminescence band exhibits two maxima in the case of strong electron-phonon coupling. The stabilization of an excited electronic state in the course of luminescence at the fundamental frequency and generation of higher optical harmonics in the field of intense laser radiation is discussed.