Widths of the peaks of single-phonon scattering of neutrons by a molecular crystal

Assuming that the molecules are rigid, the width and displacement of a peak for coherent single-phonon scattering of neutrons by an anharmonic molecular crystal is determined.     

β-Aminovinyl ketonates with heterocyclic fragments

-Aminovinyl ketones containing heterocyclic fragments (tetrahydro-1-6,2-benzothiazine 1,1-dioxide and 2,3-dimethyl-1-phenyl-2,5-dihydro-1H-pyrazole-5-one) (LH) and their complexes with 3d-metals (Co^II, Ni^II, Cu^II, and Zn^II) were synthesized. The obtained ligands give rise to two types of ML₂ chelates with coordinated (coordination number 6; Co, Ni, Zn) and uncoordinated carbonyl group in the pyrazole fragment (coordination number 5; Cu).Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 10, 2004, pp. 1709–1713.Original Russian Text Copyright © 2004 by Anpilova, Korshunov, Bicherov, Burlov, Borodkin, Zaletov, Uflyand, Garnovskii.This revised version was published online in April 2005 with a corrected cover date.     

Metal Complexes with Novel Ambidentate Ligands: β-Enaminovinylketones with Annelated 1,2-Benzothiazine-1,1-Dioxide Fragment and Antipyrine Substituent

The data on competitive binding of ligands in metal complexes with ambidentate ligands (Schiff bases and -aminovinylketones) were summarized. Special attention is given to chemical and electrochemical syntheses and structural study of novel chelates of heterocyclic enaminoketones with antipyrine substituent that form tetrahedral (Cu²⁺, Zn²⁺) or octahedral (Co²⁺, Ni²⁺) structures.     

IR-Spectroscopic Analysis of Hard Tissues of Lower “Wisdom” Teeth at the Eruption Stage of Connective Tissue Dysplasia

Journal of Applied Spectroscopy - A spectral analysis of the enamel, the enamel–dentin junction, and the dentin of human teeth with and without dysplasia of the connective tissue was carried...     

Finite-temperature perturbation theory for the random directed polymer problem

We study the random directed polymer problem—the short-scale behavior of an elastic string (or polymer) in one transverse dimension subject to a disorder potential and finite temperature fluctuations. We are interested in the polymer short-scale wandering expressed through the displacement correlator 〈[δu(X)]²〉, with δu(X) being the difference in the displacements at two points separated by a distance X. While this object can be calculated at short scales using the perturbation theory in higher dimensions d > 2, this approach becomes ill-defined and the problem turns out to be nonperturbative in the lower dimensions and for an infinite-length polymer. In order to make progress, we redefine the task and analyze the wandering of a string of a finite length L. At zero temperature, we find that the displacement fluctuations 〈[δu(X)]²〉 ∝ LX ² depend on L and scale with the square of the segment length X, which differs from a straightforward Larkin-type scaling. The result is best understood in terms of a typical squared angle 〈α²〉 ∝ L, where α = ? _x u, from which the displacement scaling for the segment X follows naturally, 〈[δu(X)]²〉 ∝ 〈α²〉 X ². At high temperatures, thermal fluctuations smear the disorder potential and the lowest-order results for disorder-induced fluctuations in both the displacement field and the angle vanish in the thermodynamic limit L → ∞. The calculation up to the second order allows us to identify the regime of validity of the perturbative approach and provides a finite expression for the displacement correlator, albeit depending on the boundary conditions and the location relative to the boundaries.     

Magnetic Neutron Diffraction of Quasi-Two-Dimensional Magnets

Crystallography Reports - This study is devoted to magnetic neutron diffraction analysis (elastic neutron scattering yielding information about spin ordering in magnetic materials). Experimental...