Structural and optical properties of WO<Subscript>3</Subscript> electrochromic layers prepared by the sol-gel method

Thin layers of tungsten trioxide have been prepared from an aqueous solution of peroxotungstic acid (PTA) using the sol-gel method. Compositional, structural and optical characteristics of WO₃ coated on indium tin oxide (ITO) conductive glass substrates were studied using X-ray diffractometery (XRD), cyclic voltammetery (CV), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Monoclinic and triclinic crystalline structures for thin film and powdered WO₃ were confirmed by XRD analysis. SEM micrograph of annealed samples revealed micro cracks due to a decrease in density and a contraction of layers. EDX analysis showed that 1∶2 ratio of oxygen and tungsten atoms in the prepared films is obtained at heat treatment temperatures higher than 200 °C. Furthermore, the annealed samples showed very good electrochromic behavior in cyclic voltammetery studies. Refractive index “n” and extinction coefficient “k” values were found to be reduced by increasing the wavelength and decreasing the temperature.     

Super Universality of the Quantum Hall Effect and the?“Large N Picture” of the ? Angle

It is shown that the “massless chiral edge excitations” are an integral and universal aspect of the low energy dynamics of the ϑ vacuum that has historically gone unnoticed. Within the SU(M+N)/S(U(M)×U(N)) non-linear sigma model we introduce an effective theory of “edge excitations” that fundamentally explains the quantum Hall effect. In sharp contrast to the common beliefs in the field our results indicate that this macroscopic quantization phenomenon is, in fact, a super universal strong coupling feature of the ϑ angle with the replica limit M=N=0 only playing a role of secondary importance. To demonstrate super universality we revisit the large N expansion of the CP ^N−1 model. We obtain, for the first time, explicit scaling results for the quantum Hall effect including quantum criticality of the quantum Hall plateau transition. Consequently a scaling diagram is obtained describing the cross-over between the weak coupling “instanton phase” and the strong coupling “quantum Hall phase” of the large N theory. Our results are in accordance with the “instanton picture” of the ϑ angle but fundamentally invalidate all the ideas, expectations and conjectures that are based on the historical “large N picture.”     

The effect of electron irradiation on the optical properties of the natural armenian zeolite-clinoptilolite

Infrared (IR) absorption and luminescence in chemically and radiation-modified natural Armenian Zeolite (clinoptilolite) samples have been studied. The luminescence was studied in 390–450 nm and 620–710 nm wavelength bands, and the IR measurements were carried out in the 400–5400 cm⁻¹ range. It is shown that the luminescence intensity depends on the content of pure clinoptilolite in the samples and, probably on the distribution of “passive” luminescence centers over Si and Al sites that became “active” under radiation or chemical treatment. The samples of electron irradiated clinoptilolite have higher luminescence intensity than the chemically and thermally treated ones. A decrease in the intensity of IR absorption bands at 3550 cm⁻¹ and 3650 cm⁻¹ was found after irradiation.     

Editorial – Introductory remarks on “Discussion &; Debate: Rogue Waves – Towards a Unifying Concept?”

This short editorial contains the introductory remarks for the special issue “discussions and debates” on the subject of “rogue waves”. This issue is the first of its kind, in the sense that the authors have the chance to discuss the basic concepts of an emerging topic in science. Based on these discussions, an attempt to give a “definition” of a rogue wave is made.     

Quantum de Sitter algebra and some possible applications in cosmology

I summarize results recently obtained in collaboration with Amelino-Camelia, Bruno and Mandanici (preprint University of Rome “La Sapienza”, August, 2005) that concern an analysis of the path of a massless particle in a q-de Sitter space-time and an approximation scheme suitable for the corresponding analysis in a quantum FRW Universe. On the basis of some arguments in the quantum-gravity literature, the q deformation parameter is assumed to depend on both the Planck scale and the curvature, leading to results that are significantly different from those of other studies of Planck-scale effects in cosmology, where the possibility of an interplay between curvature and Planck scale was ignored. Presented at the International Colloquium “Integrable Systems and Quantum Symmetries”, Prague, 16–18 June 2005.     

Einstein’s “Zur Elektrodynamik...” (1905) Revisited, With Some Consequences

Einstein, in his “Zur Elektrodynamik bewegter K?rper”, gave a physical (operational) meaning to “time” of a remote event in describing “motion” by introducing the concept of “synchronous stationary clocks located at different places”. But with regard to “place” in describing motion, he assumed without analysis the concept of a system of co-ordinates.In the present paper, we propose a way of giving physical (operational) meaning to the concepts of “place” and “co-ordinate system”, and show how the observer can define both the place and time of a remote event. Following Einstein, we consider another system “in uniform motion of translation relatively to the former”. Without assuming “the properties of homogeneity which we attribute to space and time”, we show that the definitions of space and time in the two systems are linearly related. We deduce some novel consequences of our approach regarding faster-than-light observers and particles, “one-way” and “two-way” velocities of light, symmetry, the “group property” of inertial reference frames, length contraction and time dilatation, and the “twin paradox”. Finally, we point out a flaw in Einstein’s argument in the “Electrodynamical Part” of his paper and show that the Lorentz force formula and Einstein’s formula for transformation of field quantities are mutually consistent. We show that for faster-than-light bodies, a simple modification of Planck’s formula for mass suffices. (Except for the reference to Planck’s formula, we restrict ourselves to Physics of 1905.)     

Giant magnetoresistance in Hg<Subscript>1−x−y</Subscript>Mn<Subscript>x</Subscript>Fe<Subscript>y</Subscript>Te crystals

Giant magnetoresistance in Hg _1−x−y Mn _x Fe _y Te crystals is caused by clusters with “antiferromagnetic” (Mn-Te-Mn-Te, Mn-Te-Fe-Te) and “ferromagnetic” (Fe-Fe-Fe) ordering. The effect is due to the fact that the charge carriers taking part in electric current interact with the “ferromagnetic” cluster subsystem (Fe-Fe-Fe) magnetized to saturation and become spin-polarized. These spin-polarized charge carriers are strongly scattered by the “antiferromagnetic” Mn-Te-Mn-Te and Mn-Te-Fe-Te clusters, because the magnetic moments inside the clusters and resultant moments of clusters have chaotic orientations. Investigations of kinetic coefficients of Hg _1−x−y Mn _x Fe _y Te crystals before and after thermal treatment show that there is no marked correlation between the giant magnetoresistance and charge-carrier concentration, mobility, and band parameters of crystals. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 28–33, October, 2007.     

Structure of tetraphenylporphyrinatocobalt(II) low-temperature sublimates

Armenian Institute of Applied Chemistry “ARIAK”, Artsakha Ave., Lane 4, Bld. 5, Erevan, 375005, Armeniya. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 62, No. 6, pp. 62–66, November–December, 1995.     

Periodic domain structures obtained by growth of LiNbO<Subscript>3</Subscript> crystals doped with gadolinium

The growth of a periodic domain structure in LiNbO₃ crystals doped with gadolinium (Gd, 0.44 wt %) was investigated by special electron beam surface charging in a scanning electron microscope and on a atomic force microscope. Ferroelectric domain boundaries with “tail-to-tail” and “head-to-head” P _s orientations were comparatively analyzed. The domain boundaries had different forms and differed by their physical properties. Micron-size surface crystal regions close to the “tail-to-tail” boundaries were charged slower by electron irradiation and had modified elastic properties. This region was detected by using the lateral force mode of atomic force microscopy. The observed morphology and property features were supposed to be due to different concentration gradients of the Gd impurity and different width of its distribution close to the domain boundaries of different types.     

Decoherence within a single atom

An “almost diagonal” reduced density matrix (in coordinate representation) is usually a result of environment induced decherence and is considered the sign of classical behavior. We show that the proton of a ground state hydrogen atom can indeed possess such a density matrix. This example demonstrates that the “almost diagonal” structure may be derived from an interaction with a low number of degrees of freedom which play the role of the environment. We also show that decoherence effects in our example can only be observed if the interaction with the measuring device is significantly faster than the interaction with the environment (the electron). In the opposite case, when the interaction with the environment is significant during the measurement process, coherence is maintained. Finally, we propose a neutron scattering experiment on cold He atoms to observe decoherence which shows up as an additional positive contribution to the differential scattering cross section. This contribution is inversely proportional to the bombarding energy.     

Improved (1s)<Superscript>2</Superscript> variational model for helium

The ground-state energy of neutral helium is estimated variationally with a trial wavefunction of the form ϕ≈e ^−γ(rA/a _o)ⁿe^−γ(rB/a _o)ⁿ. This model represents a modification of traditional textbook examinations of this problem via inclusion of the power “n” as a second nonlinear variational parameter in addition to the usual effective nuclear charge γ and leads to an upper-limit on the ground state energy of −2.86107 E _h (E _h =1 hartree) in comparison with the traditional (n=1) result of −2.84766 E _h . This result represents a reduction of the percentage overestimate from the true ground-state energy (−2.90373 E _h ) of from 1.93 to 1.47. In comparison with the maximum accuracy obtainable from an uncorrelated trial wavefunction, −2.86168 E _h , the present trial wavefunction reduces the percentage overestimate from 0.49 (n=1) to 0.021. The optimum values of (n, γ) are determined to be ≈(0.897, 1.825).     

Glueballs,gluerings, and gluestars in the <Emphasis Type="Italic">d</Emphasis> = 2 + 1 <Emphasis Type="Italic">SU</Emphasis>(<Emphasis Type="Italic">N</Emphasis>) gauge theory

The 3d gluodynamics which governs the large-T quark—gluon plasma is studied in the framework of the field correlator method. Field correlators and spacial string tension are derived through the gluelump Green’s functions. The glueball spectrum is calculated both in C = −1 as well as in C = +1 sectors, and multigluon bound states in the form of “gluon rings” and “gluon stars” are computed explicitly. Good overall agreement with available lattice data is observed. The text was submitted by the author in English.     

Zone structure and its genesis from the states of sublattices in orthorhombic MgGeN<Subscript>2</Subscript>

It is demonstrated that the crystalline structure of MgGeN₂ can be reduced to the superposition of “approximated” high-symmetry Bravais sublattices by shifting atoms in a unit cell within the range of 5% of the lattice constant. The superimposed Brillouin zones were plotted for crystal lattices and sublattices. The computational results are presented for the electronic structure of MgGeN₂ in terms of the theory of the density function. The influence of “hidden” symmetry in this crystal on zone spectra is described.     

<Emphasis Type="Italic">q</Emphasis>-Analogue of Modified KP Hierarchy and its Quasi-Classical Limit

A string basis is constructed for each subalgebra of invariants of the function algebra on the quantum special linear group. By analyzing the string basis for a particular subalgebra of invariants, we obtain a “canonical basis” for every finite dimensional irreducible -module. It is also shown that the algebra of functions on any quantum homogeneous space is generated by quantum minors. Supported by the Australian Research Council and Chinese National Natural Science Foundation project number: 10471070     

Experimental investigation of ligand effects on the conversion electron spectrum of the 22.5 keV M1 + E2 nuclear transition in <Superscript>149</Superscript>Sm

The conversion electron spectrum of the 22.5keV M1 + E2 nuclear transition in ¹⁴⁹Sm from the electron capture decay of ¹⁴⁹Eu was experimentally studied for the “Eu₂O₃” and “EuF₃” compounds in which ¹⁴⁹Eu ions have the same assumed oxidation number +3 . While the energies of the L, M, N, O, and P₁ conversion lines for “EuF₃” were lower, on average, by 1.7(1), 2.7(2), 2.3(3), 4.1(2), and 5.7(9)eV, respectively, than those for “Eu₂O₃”, no changes between the two ligand complexes were observed for relative intensities of the conversion lines and their natural widths within the error limits.     

The impact of collisions on platelet distribution in the blood flow

The impact of platelet collisions on their distribution in a viscous liquid flow has been analyzed. It has been shown that platelet distribution in the flow perpendicular to current lines resulting from their collisions can be described as “shear” diffusion. In the wide physiological range of shear velocities specific for blood, the coefficient of “shear” diffusion is much larger than the coefficient of “Brownian” diffusion. For a parabolic fluid velocity profile (Poiseuille flow) in cylindrical vessel “shear” diffusion causes uneven radial distribution of platelets over the vessel radius. “Shear” diffusion causes platelet concentration to grow from the wall toward the center (vessel axis). This effect appears to be a consequence of the specific distribution of platelet collision frequency reaching its maximum at the vessel wall.     

Double passage of electromagnetic waves through magnetized plasma: approximation of independent normal waves

Polarization properties of electromagnetic waves, double-passed through magnetized plasma, are studied. Analyses are performed in the case of non-interacting normal modes, propagating in homogeneous and weakly inhomogeneous plasmas, and for three kinds of reflectors: metallic plane, 2D corner retro-reflector (2D-CR), and cubic corner retro-reflector (CCR). It is shown that an electromagnetic wave, reflected from a metallic plane and from a CCR, contains only “velocity-preserving” channels, whose phases are doubled in comparison with those of a single-passage propagation. At the same time, an electromagnetic wave reflected from a 2D-CR is shown to contain both “velocity-preserving” and “velocity-converting” channels, the latter converting the fast wave into the slow one and vice-versa. One characteristic feature of “velocity-converting” channels is that they reproduce the initial polarization state near the source, which might be of practical interest for plasma interferometry. In the case of circularly polarized modes, “velocity-preserving” channels completely disappear, and only “velocity-converting” channels are to be found.     

“Elastic” fluctuation-induced effects in smectic wetting films

The Li-Kardar field theory approach is generalized to wetting smectic films and the “elastic” fluctuation-induced interaction is obtained between the external flat bounding surface and distorted IA (isotropic liquid-smectic A) interface acting as an “internal” (bulk) boundary of the wetting smectic film under the assumption that the IA interface is essentially “softer” than the surface smectic layer. This field theory approach allows calculating the fluctuation-induced corrections in Hamiltonians of the so-called “correlated” liquids confined by two surfaces, in the case where one of the bounding surfaces is “rough” and with different types of surface smectic layer anchoring. We obtain that in practice, the account of thermal displacements of the smectic layers in a wetting smectic film reduces to the addition of two contributions to the IA interface Hamiltonian. The first, so-called local contribution describes the long-range thermal “elastic” repulsion of the fluctuating IA interface from the flat bounding surface. The second, so-called nonlocal contribution is connected with the occurrence of an “elastic” fluctuation-induced correction to the stiffness of the IA interface. An analytic expression for this correction is obtained.     

Half-life estimation under indefinite “mother-daughter” relation

An algorithm has been proposed to build an estimate of the half-life of a “daughter” nucleus in case, when it is unknown, which nucleus is its “mother” (“indefinite start time”). For a decay of the “mother” at an instant t we can determine P—a probability of such a decay, if we assume that each “mother”, which has been decayed before t has equal chances to be “mother” of this “daughter”: