A few points on omnidirectional band gaps in one-dimensional photonic crystals

The universal condition for the formation of omnidirectional band gaps (OBG) in photonic crystal (PC) was derived with consideration of permeability of the materials. And it was found that there are four kinds of PCs: one of them has no OBG, and one always possesses OBG. For the other two kinds of PCs, there are OBG for only TM or TE waves respectively. Moreover, in all PCs, the OBG can be broadened by decreasing the refractive index of the ambient medium or/and increasing the contrast between the wave impedances of the component materials of the PC. PACS 42.70.Qs; 71.20.Tx     

Creation of a donor-acceptor pair for studying intraprotein electron transfer with the participation of amino-acid derivatives of fullerene C60

Efficient quenching of eosin phosphorescence by amino-acid derivatives of fullerene (AADFs) such as C₆₀-alanine and C₆₀-glycine in aqueous solutions indicates the possibility of transferring electrons from eosin to fullerene upon collisions or in the exciplex state. To investigate electron transfer in the protein structure, we studied the process of incorporation of C₆₀-alanine and C₆₀-glycine into the heme pocket of myoglobin by controlling Förster quenching. The dissociation constant for the protein-AADF complex was estimated.     

Synthesis, structure and optical properties of Eu/TiO2 nanocrystals at room temperature

The nanocrystal samples of titanium dioxide doped with europium ion (Eu³⁺/TiO₂ nanocrystal) are synthesized by the sol-gel method with hydrothermal treatment. The Eu³⁺ contents (molar ratio) in the samples are 0, 0.5%, 1%, 2%, 3% and 4%. The X-ray diffraction, UV-Vis spectroscopy data and scanning electron microscope image show that crystallite size is reduced by the doping of Eu³⁺ into TiO₂. Comparing the Raman spectra of TiO₂ with Eu³⁺/TiO₂ (molar ratio Eu³⁺/TiO₂=1%, 2% and 4%) nanocrystals at different annealing temperatures indicates that the anatase-to-rutile phase transformation temperatures of Eu³⁺/TiO₂ nanocrystals are higher than that of TiO₂. This is due to the formation of Eu-O-Ti bonds on the surface of the TiO₂ crystallite, as characterized by the X-ray photoelectron spectroscopy. The photoluminescence spectra of TiO₂ in Eu³⁺/TiO₂ nanocrystals are interpreted by the surface self-trapped and defect-trapped exciton relaxation. The photoluminescence of Eu³⁺ in Eu³⁺/TiO₂ nanocrystals has the strongest emission intensity at 2% of Eu³⁺ concentration.     

Integrability of a system of two nonlinear Schrödinger equations

P. P. Shirshov Institute of Oceanology, USSR Academy of Sciences. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 79, No. 2, pp. 180–184, May, 1989.     

Physicochemical aspects of preservation of cellulose paper with polymers

The process of preservation of newspaper with aqueous solutions and dispersions of acrylic copolymers is considered from the instant of impregnation till removal of the polymeric preservative from paper.     

System dependence of the correlation function of IMFs in Ar + Sn at 35 MeV/u

The inclusive reduced velocity correlation functions of the intermediate mass fragments were measured in the reactions of ³⁶Ar + ^112,124Sn at 35 MeV/u. The anti-correlation is observed to be stronger in ³⁶Ar + ¹²⁴Sn system than that in ³⁶Ar + ¹¹²Sn. The difference of the correlation functions between the two reactions is mainly contributed by the particle pairs with high momenta. A three body Coulomb repulsive trajectory model is employed to calculate the emission time scale of the IMFs for the two systems. The time scale is 150 fm/c in ³⁶Ar + ¹¹²Sn and 120 fm/c in the ³⁶Ar + ¹²⁴Sn, respectively.     

A polynomial algorithm for one problem of guillotine cutting

We consider the problem of guillotine cutting a rectangular sheet into two rectangular pieces without rotations. The question is whether there exists a cutting pattern with given numbers of occurrences of both rectangular pieces. A polynomial time algorithm is described to construct the convex hull of solutions to this problem.     

Energy of formation for and liquid binary alloys

We have investigated the free energy of formation for Ag_xIn_1-x and Ag_xSn_1-x liquid binary alloys at temperatures 1173 and 1250 K, respectively. A microscopic theory based on the first order perturbation has been applied. The interionic interaction and a reference liquid are the fundamental components of the theory. The interionic interaction is described by a local pseudopotential. A liquid of hard spheres (HS) of two different effective diametres and charges is used to describe the reference system. The results of the calculations for energy of formation agree very well with the available experimental data. Our calculations also reveal that a simple perturbative approach along with appropriate effective pair potentials can produce nearly quantitative results for the concerned alloys.