Photoconductivity,Antioxidant, and Antimicrobial Activities of Some Acenaphthenequinone Derivatives

Russian Journal of General Chemistry - Photoconductive acenaphthenequinone derivatives have been synthesized by a one-pot process of acenaphthenequinone with different aromatic hydrazides...     

Electrical Conductivity in a Laser Beam Channel

Russian Physics Journal - Electrical conductivity in a laser beam channel has been investigated. Oscillations of the conductivity caused by the oscillation motion of electrons in laser-induced...     

Energy Characteristics of Non-Resonator Generation in Nanodispersed Active Media Irradiated with Femtosecond Laser Pulses

Russian Physics Journal - Results of experimental measurements of the energy characteristics of stimulated emission in coumarin-30 and rhodamine 6G dyes with nanoparticles under irradiation with...     

Joint bounds for the Perron roots of nonnegative matrices with applications

Given a finite set {A_x}_{x ∈ X} of nonnegative matrices, we derive joint upper and lower bounds for the row sums of the matrices D⁻¹ A^(x) D, x ∈ X, where D is a specially chosen nonsingular diagonal matrix. These bounds, depending only on the sparsity patterns of the matrices A^(x) and their row sums, are used to obtain joint two-sided bounds for the Perron roots of given nonnegative matrices, joint upper bounds for the spectral radii of given complex matrices, bounds for the joint and lower spectral radii of a matrix set, and conditions sufficient for all convex combinations of given matrices to be Schur stable. Bibliography: 20 titles. __________ Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 334, 2006, pp. 30–56.     

Rearrangements in Real Estate Investments

In this note we consider an investment problem in real estate. We show that it can be formulated in terms of a constrained optimization problem, and this leads to a linear rearrangement optimization problem. We address existence, uniqueness, and symmetry of the optimal solution.     

Microstructural and optical properties of europium-doped zinc oxide nanowires

Single-crystal Eu³⁺-doped wurtzite ZnO micro- and nanowires were synthesized by chemical vapor deposition. The nanostructures grew via a self-catalytic mechanism on the walls of an alumina boat. The structure and properties of the doped ZnO were characterized using X-ray diffraction, energy-dispersive X-ray spectroscopy, scanning and transmission electron microscopy, and photoluminescence (PL) methods. A 10-min synthesis yielded vertically grown nanowires of 50–400 nm in diameter and several micrometers long. The nanowires grew along the ±[0001] direction. The Eu³⁺ concentration in the nanowires was 0.8 at.%. The crystal structure and microstructure of were compared for Eu³⁺-doped and undoped ZnO. PL spectra showed a red shift in emission for Eu³⁺-doped (2.02 eV) compared to undoped ZnO nanowires (2.37 eV) due to Eu³⁺ intraionic transitions. Diffuse reflectance spectra revealed widening of the optical bandgap by 0.12 eV for Eu³⁺-doped compared to undoped ZnO to yield a value of 3.31 eV. Fourier-transform infrared spectra confirmed the presence of europium in the ZnO nanowires.     

Graphene to graphite; a layer by layer experimental measurements and density function theory calculations of electric conductivity

ABSTRACT

We measured the electric conductivity of large (25?×?50?mm) graphene films as a function of number of layers in the range of 1–20 layers. We also calculated the energy gap for such samples using density function theory. Our results showed a conductivity slightly above that of ITO for monolayer graphene and an exponential decrease as the number of graphene layers increased. Both experimental and simulation results showed a convergence of graphene into graphite at as little as 18–20 layers.