Synthesis of Mono- and Tetraalkylamide Derivatives of <Emphasis Type="Italic">p</Emphasis>-<Emphasis Type="Italic">tert</Emphasis>-Butylthiacalix[4]arene

Mono- and tetrasubstituted derivatives of p-tert-butylthiacalix[4]arene containing acrylate and acrylamide fragments are synthesized for the first time. The Michael aza-addition of benzylamine to the synthesized acrylamide and acrylate thiacalixarene derivatives is studied.     

Magnetoreflection of light in CoFe<Subscript>2</Subscript>O<Subscript>4</Subscript> magnetostrictive spinel

The reflection and magnetoreflection of natural light within the infrared spectral range is studied in single crystals of CoFe₂O₄ ferrimagnetic ferrite spinel. Correlation between the reflection of light and magnetoelastic characteristics of this spinel is found. It is shown that the most significant magnetic-field-induced changes in the magnetoreflection of the spinel occur near the fundamental absorption edge and within the range of the phonon spectrum.     

13C NMR study of 2,3,4,5-tetraphenylsilole dilithium salt

The complete assignment of the signals in the¹³C NMR spectra of 2,3,4,5-tetraphenyl-1-R¹,R²-1-silacyclopenta-2,4-dienes (R¹=R²=H, Me) and of the dianion of lithium salt [(PhC)₄Si]²⁻·2Li⁺ was carried out by 2D NMR spectroscopy. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 216–218, January, 1999.     

In situ CP MAS NMR spectroscopy under continuous-flow conditions to monitor real time dynamics during propene polymerization over a supported Ziegler catalyst

In situ propene polymerization was observed using CP MAS (cross polarization with magic angle spinning) ¹³C NMR spectroscopy under the conditions of continuously flowing propene through a supported Ziegler catalyst treated with triethylaluminium. The signals at 44, 26, and 22 ppm attributed to the CH₂, CH, and CH₃ groups of polypropene, respectively, were found to appear upon exposure to the propene flow (0.1 L/min). An increase in intensities of these lines was observed for 30 min, then they remained approximately constant. The cross-polarization parameters of nascent polypropene, measured using standard techniques, were close to those of typical crystalline polypropene. The technique has a great potential as an effective tool for the investigation of the polypropene formation on the Ziegler catalyst.     

Image jitter of a laser guide star in a monostatic formation scheme

The image jitter of a spherical wave with a random center is calculated. A rigorous formula is proposed for a random vector that determines the image position of the spherical wave at the focus of the telescope under the condition that the source position also fluctuates. The variance of these fluctuations is calculated. The dependence of the variance on parameters describing the optical experiment is analyzed. The analysis of this problem is of interest for solving of a number of practical tasks including the analysis of the possibility of solution of the tilt problem upon using a laser guide star.     

Numerical Simulation of Gravity Waves Excited in the Ocean by Low-Frequency Surface Seismic Waves Based on GPS Recordings

A numerical experiment for reproducing the generation of free gravity waves in the ocean by low-frequency surface seismic waves passing across the bottom is described. The dynamics of the bottom movement is reconstructed based on the real GPS data recorded during the disastrous Tohoku earthquake of March 11, 2011. Results of the numerical simulation show that horizontal movements of underwater slopes play a key role in the generation of free gravity waves.     

Effects of the azimuthal-angle focusing of atoms ejected from the (001) Ni and (001) Au faces

The features of the azimuthal-angle focusing of atoms sputtered from the surfaces of the Ni (001) and Au (001) faces are studied by molecular dynamics using computer simulation. The degree of anisotropy of the azimuthal-angle distribution for atoms sputtered from the (001) Au surface is found to be higher than for atoms sputtered from the (001) Ni face. It is shown that two maxima are observed at comparatively small polar observation angles in the azimuthal-angle distribution in the directions in which Wehner spots are formed, i.e., to the left and to the right of the center of the lens formed by two neighbors closest to the ejected atom. The maxima are shifted from the center with a decrease in the polar observation angle. This feature occurs due to the rainbow scattering effect. The contribution of atoms overfocused with respect to the lens center is studied. All overfocused atoms are found to be strongly blocked. When atoms are ejected from the (001) Au face, the interaction cross section strongly increases due to an increase in the atomic number, and the effects of blocking and focusing appear to be more pronounced.     

Skin effect under the conditions of ferromagnetic and spin-wave resonance

An expression for the electromagnetic field penetration depth in a metallic magnetic layer is derived taking into account the complexity of the high-frequency permeability under the conditions of ferromagnetic and spin-wave resonance. The frequency dependences of the skin depth and its dependences on the magnitude and type of spin pinning are determined from a numerical analysis of the solutions of the motion equation for magnetization. Some features of the dependences associated with the nature of the spin-wave spectrum are revealed.     

Output stabilization in uncertain many input-many output systems

The article considers robust output stabilization of a class of uncertain many input-many output systems. The problem is solved by the method of asymptotic invariance in the class of continuous feedbacks. Transients in the closed-loop control systems are estimated and the dependence of transient performance on observer and feedback parameters is investigated. Translated from Nelineinaya Dinamika i Upravlenie, pp. 159–172, 1999.     

The Kinetics of Formation of Microporous Polytriazine in Diphenyl Sulfone

This study highlights the value of nonisothermal kinetic methods in selecting temperature conditions for the isothermal preparation of microporous polymeric materials. A dicyanate ester is synthesized and the kinetics of its polymerization in diphenyl sulfone are studied by calorimetry under nonisothermal conditions. The kinetics are analyzed by a model-based approach, using the Kamal model, as well as by a model-free approach, using an advanced isoconversional method. Both approaches correctly predict the time to completion of polymerization at a given temperature. The material prepared independently at the predicted temperature is characterized by electron microscopy and CO₂ adsorption measurements and is confirmed to possess a microporous structure with a multimodal distribution of micropores with two major maxima at ~0.5 and 0.8 nm.