A TEMPO-like nitroxide combined with an alkyl-substituted pyridine: An efficient catalytic system for the selective oxidation of alcohols with iodine

An efficient method for the oxidation of alcohols to aldehydes or ketones in a two-phase CH₂Cl₂/NaHCO₃ (aq.) system, using iodine and catalytic amounts of 4-acetylamino-2,2,6,6-tetramethylpiperidine-1-oxyl and 2,4,6-trimethylpyridine, was developed. The performance of the method was demonstrated by the selective oxidation of 37 variously substituted alcohols in ≥90% yield, including the gram-scale synthesis of the important chemical 2,5-diformylfuran from biomass-derived 5-hydroxylmethylfurfural.     

Phonon Spectroscopy of the Schottky-Like Low-Energy Paramagnetic Excitations in Garnet Solid Solution Crystals

Journal of Experimental and Theoretical Physics - The interaction of weakly nonequilibrium phonons with the low-energy paramagnetic excitations of the rare-earth ions of the yttrium series in...     

Features of the Development of the Small-Scale Self-Focusing in Superpower Femtosecond Lasers

Radiophysics and Quantum Electronics - The physical reason for the difference between the small-scale self-focusing of nanosecond and femtosecond pulses is that the typical intensity of the latter...     

Diffusion of Phonons in Polycrystalline YAG Ceramic Samples at Liquid-Helium Temperatures,According to the Stationary and Non-Stationary Measurement Data

Crystallography Reports - The specific features of the transport of thermal-frequency phonons at liquid-helium (He) temperatures under the conditions of non-stationary measurements and thermal...     

Phonon spectroscopy of submicron ceramic materials based on Ce1–xGdxO2–y solid solutions

The specific features of the kinetic characteristics of subterahertz phonons in ceramic samples based on Ce_1–x Gd _x O_2–y electrolyte solid solutions have been investigated in the range of liquid-helium temperatures. It has been demonstrated that the observed anomalies of the transport characteristics of thermal phonons in this system are caused by the formation of structural defects associated with the position of vacancies in the anion sublattice with respect to impurity cations. The activation energy of the two-level system Δ = 8.53 K has been determined from an analysis of the experimental results.     

Non-dispersive traveling waves in inclined shallow water channels

Existence of traveling waves propagating without internal reflection in inclined water channels of arbitrary slope is demonstrated. It is shown that traveling non-monochromatic waves exist in both linear and nonlinear shallow water theories in the case of a uniformly inclined channel with a parabolic cross-section. The properties of these waves are studied. It is shown that linear traveling waves should have a sign-variable shape. The amplitude of linear traveling waves in a channel satisfies the same Green's law, which is usually derived from the energy flux conservation for smoothly inhomogeneous media. Amplitudes of nonlinear traveling waves deviate from the linear Green's law, and the behavior of positive and negative amplitudes are different. Negative amplitude grows faster than positive amplitude in shallow water. The phase of nonlinear waves (travel time) is described well by the linear WKB approach. It is shown that nonlinear traveling waves of any amplitude always break near the shoreline if the boundary condition of the full absorption is applied.