Beam spreading of vortex beams propagating in turbulent atmosphere

We present some results obtained by numerical modeling of the propagation of vortex beams LG(0l) through a randomly inhomogeneous medium. The vortex beams are the lower order Laguerre-Gaussian modes. Such beams, if propagated under conditions of weak turbulence, also experience distortions, like a Gaussian beam. However, the statistically averaged vortex beams (LG(0l)) conserve the central intensity dip with a nonzero intensity on the beam axis. The beam broadening of vortex beams is analyzed. The average vortex beams are found to be broadened less than the Gaussian beam while propagated through a randomly inhomogeneous medium. The higher the topological charge l is, the smaller the beam broadening is.     

Spectroscopic parameters of the absorption bands related to the local vibrational modes of carbon and oxygen impurities in silicon enriched with <Superscript>28</Superscript>Si, <Superscript>29</Superscript>Si,and <Superscript>30</Superscript>Si isotopes

The IR spectra of all three Si isotopes in the form of bulk single crystals (²⁸Si with an enrichment of more than 99.9%, and ²⁹Si and ³⁰Si with an enrichment of more than 90%) have been studied at T = 300, 17, and 5 K in the spectral range 550–1200 cm^?1. The IR active local vibrational modes (LVM) of Si-¹²C centered at 605 cm^?1 and Si-¹⁶O-Si quasi-molecules in the region of 1136 cm^?1 for all the Si isotopes, in comparison with Si possessing a natural isotopic composition, as well as their isotopic shift at 300 and 17 K, have been determined. The dependence of the shape of the antisymmetric stretching vibration band for ²⁸Si-¹⁶O-²⁸Si in the spectrum of ²⁸Si on spectral resolution has been studied. The possibility of generalizing the IR spectroscopy method for the determination of carbon and oxygen impurities in Si possessing a natural isotopic composition to monoisotopic Si have been discussed.     

The Enigmatic Nature of the TCR-pMHC Interaction: Implications for CAR-T and TCR-T Engineering

The interaction of the T-cell receptor (TCR) with a peptide in the major histocompatibility complex (pMHC) plays a central role in the adaptive immunity of higher chordates. Due to the high specificity and sensitivity of this process, the immune system quickly recognizes and efficiently responds to the appearance of foreign and altered self-antigens. This is important for ensuring anti-infectious and antitumor immunity, in addition to maintaining self-tolerance. The most common parameter used for assessing the specificity of TCR-pMHC interaction is affinity. This thermodynamic characteristic is widely used not only in various theoretical aspects, but also in practice, for example, in the engineering of various T-cell products with a chimeric (CAR-T) or artificial (TCR-engineered T-cell) antigen receptor. However, increasing data reveal the fact that, in addition to the thermodynamic component, the specificity of antigen recognition is based on the kinetics and mechanics of the process, having even greater influence on the selectivity of the process and T lymphocyte activation than affinity. Therefore, the kinetic and mechanical aspects of antigen recognition should be taken into account when designing artificial antigen receptors, especially those that recognize antigens in the MHC complex. This review describes the current understanding of the nature of the TCR-pMHC interaction, in addition to the thermodynamic, kinetic, and mechanical principles underlying the specificity and high sensitivity of this interaction.     

Stabilization of Heavy Vacuum Gas Oil when Producing Lubricating Oils

Chemistry and Technology of Fuels and Oils - A unit for separating heavy vacuum gas oil of a stabilized composition from a wide fraction of vacuum gas oil with a capacity of 65,000 tons per year is...     

Effect of Process Regimes on the Life of “Mayerton” Linings in 385-Ton Steel Teeming Ladles

The effect of performance factors on the life of linings of large ladles from periclase-carbon (the slag-line area) and alumopericlase-carbon (walls) refractories is considered. The studied performance factors are the changes in the properties of the refractories upon heating, the temperature regime of melting, the chemical interaction between the lining and the slag, the residence time of metal in the ladle, the causes of emergency situations, and the effect of external factors on the topography of the lining wear. Observations of 114 ladles have shown that the lining life is determined by three groups of factors. Preliminary estimates made by the authors lead them to expect that a correction of some acting conditions of operation and maintenance of the ladles will increase their life by 10 – 12% without changes in the quality of the refractories or the design of the lining.     

Serviceability of refractory mixtures for teeming ladle linings

A siliceous mixture of grade MKGF, a pouring mixture, and MMK-65 high-alumina mixture are investigated after service in teeming and intermediate ladles. The changes in the physicochemical properties of specimens from worked-out linings are described. Translated from Ogneupory i Tekhnicheskaya Keramika, No. 5, pp. 20–23, May, 1996.