Early Life Relict Feature in Peptide Mass Distribution

Molecular mass of a biomolecule is characterized in mass spectroscopy by the monoisitopic mass M~mono~ and the average isotopic mass M~av~. We found that peptide masses mapped on a plane made by two parameters derived from M~mono~ and M~av~ form a peculiar global feature in form of a band-gap 5-7 ppm wide stretching across the whole peptide galaxy, with a narrow (FWHM 0.2 ppm) line in the centre. The a priori probability of such a feature to emerge by chance is less than 1:100. Peptides contributing to the central line have elemental compositions following the rules S=0; Z = (2C - N - H)/2 =0, which nine out of 20 amino acid residues satisfy. The relative abundances of amino acids in the peptides contributing to the central line correlate with the consensus order of emergence of these amino acids, with ancient amino acids being overrepresented in on-line peptides. Thus the central line is a relic of ancient life, and likely a signature of its emergence in abiotic synthesis. The linear correlation between M~av~ and M~mono~ reduces the complexity of polypeptide molecules, which may have increased the rate of their abiotic production. This, in turn may have influenced the selection of these amino acid residues for terrestrial life. Assuming the line feature is not spurious, life has emerged from elements with isotopic abundances very close to terrestrial levels, which rules out most of the Galaxy

On the theory of transport phenomena in ferrofluids. Effect of chain-like aggregates

The paper deals with the theoretical study of the effect of chain-like aggregates on diffusion and magnetophoretic transport in ferrofluids. Analysis shows that the appearance of the chains leads to a strong anisotropy of the diffusion transport-the coefficient of diffusion in the direction of applied magnetic field is significantly more than that in the perpendicular direction. The presence of the chains in a ferrofluid strongly affects the coefficient of the particle magnetophoresis. © 2012 Elsevier B.V. All rights reserved

Shear thickening of dense suspensions due to energy dissipation in lubrication layers between particles

This paper deals with a theoretical study of the shear thickening effects in concentrated suspensions of non-Brownian particles. Our analysis shows that an increase of the shear rate of the suspension flow leads to a decrease of the mean thickness of the gaps between the nearest particles in dense suspensions. In turn, this leads to the growth of energy dissipation in these gaps, which means an increase of the suspension effective viscosity with the shear rate. © 2013 American Physical Society

Structurization of ferrofluids in the absence of an external magnetic field

Structural transformations in a model ferrofluid in the absence of an external magnetic field have been theoretically studied. The results agree with well-known laboratory experiments and computer simulations in showing that, if the concentration of particles and their magnetic interaction energy are below certain critical values, most particles form separate linear chains. If these parameters exceed the critical values, most particles concentrate so as to form branched network structures. The passage from chains to network has a continuous character rather than represents a discontinuous first-order phase transition. © Pleiades Publishing, Inc., 2013

Hydrodynamic Modes in a Trapped Strongly Interacting Fermi Gases of Atoms

The zero-temperature properties of a dilute two-component Fermi gas in the BCS-BEC crossover are investigated. On the basis of a generalization of the variational Schwinger method, we construct approximate semi-analytical formulae for collective frequencies of the radial and the axial breathing modes of the Fermi gas under harmonic confinement in the framework of the hydrodynamic theory. It is shown that the method gives nearly exact solutions.Comment: 11 page

Heat exchange within the surrounding biological tissue during magnetic hyperthermia

The paper deals with mathematical modeling and theoretical study of the heat distribution within the surrounding biological tissue during the effect of the magnetic hyperthermia. The mathematical model is formulated and solved numerically by using the finite difference method. The intensity of heat production is used in the present model. The obtained results allow predicting the temperature change in tumor as well as in the surrounding tissue depending on intensity of the tumor heating. © 2020 International Information and Engineering Technology Association.Russian Foundation for Fundamental Investigations, RFFI: 18-08-00178, 19-52-45001Ministry of Science and Higher Education of the Russian FederationThis paper has been supported by RFFI, grants 18-08-00178, 19-52-45001 and the state program of the Ministry of Science and Higher Education of the Russian Federation (theme “Magnet” and Contract No. 02.A03.21.006)

Activated Ion Electron Capture Dissociation (AI ECD) of proteins: synchronization of infrared and electron irradiation with ion magnetron motion.

Here, we show that to perform activated ion electron capture dissociation (AI-ECD) in a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer equipped with a CO(2) laser, it is necessary to synchronize both infrared irradiation and electron capture dissociation with ion magnetron motion. This requirement is essential for instruments in which the infrared laser is angled off-axis, such as the Thermo Finnigan LTQ FT. Generally, the electron irradiation time required for proteins is much shorter (ms) than that required for peptides (tens of ms), and the modulation of ECD, AI ECD, and infrared multiphoton dissociation (IRMPD) with ion magnetron motion is more pronounced. We have optimized AI ECD for ubiquitin, cytochrome c, and myoglobin; however the results can be extended to other proteins. We demonstrate that pre-ECD and post-ECD activation are physically different and display different kinetics. We also demonstrate how, by use of appropriate AI ECD time sequences and normalization, the kinetics of protein gas-phase refolding can be deconvoluted from the diffusion of the ion cloud and measured on the time scale longer than the period of ion magnetron motion

The law of action and reaction for the effective force in a nonequilibrium colloidal system

We study a nonequilibrium Langevin many-body system containing two 'test' particles and many 'background' particles. The test particles are spatially confined by a harmonic potential, and the background particles are driven by an external driving force. Employing numerical simulations of the model, we formulate an effective description of the two test particles in a nonequilibrium steady state. In particular, we investigate several different definitions of the effective force acting between the test particles. We find that the law of action and reaction does not hold for the total mechanical force exerted by the background particles, but that it does hold for the thermodynamic force defined operationally on the basis of an idea used to extend the first law of thermodynamics to nonequilibrium steady states.Comment: 13 page

Transport Phenomena in Complex Systems (part 1)

The issue, in two parts, is devoted to theoretical, computational and experimental studies of transport phenomena in various complex systems (in porous and composite media; systems with physical and chemical reactions and phase and structural transformations; in biological tissues and materials). Various types of these phenomena (heat and mass transfer; hydrodynamic and rheological effects; electromagnetic field propagation) are considered. Anomalous, relaxation and nonlinear transport, as well as transport induced by the impact of external fields and noise, is the focus of this issue. Modern methods of computational modelling, statistical physics and hydrodynamics, nonlinear dynamics and experimental methods are presented and discussed. Special attention is paid to transport phenomena in biological systems (such as haemodynamics in stenosed and thrombosed blood vessels magneto-induced heat generation and propagation in biological tissues, and anomalous transport in living cells) and to the development of a scientific background for progressive methods in cancer, heart attack and insult therapy (magnetic hyperthermia for cancer therapy, magnetically induced circulation flow in thrombosed blood vessels and non-contact determination of the local rate of blood flow in coronary arteries). The present issue includes works on the phenomenological study of transport processes, the derivation of a macroscopic governing equation on the basis of the analysis of a complicated internal reaction and the microscopic determination of macroscopic characteristics of the studied systems. This article is part of the theme issue 'Transport phenomena in complex systems (part 1)'. © 2021 The Author(s).Data accessibility. This article has no additional data. Authors’ contributions. All authors contributed equally to the present paper. Competing interests. We declare we have no competing interests. Funding. This work was supported by the Russian Science Foundation (project no. 18-19-00008)

A Study of Easy Magnetization Axes of Ferro-nanoparticles on Magnetic Hyperthermia

This work deals with theoretical approach and mathematical modeling of hyperthermia effect by single-domain ferro-nanoparticles. The magnetic particles have the Neel relaxation particles of the easy magnetization axes. The system is happened under external magnetic field. Two situations of systems, system of approximation of non-interaction chaotic particles like single particle and system of chain-like two particles are considered into account whereas these particles are in strong magnetic anisotropy. Our analysis shows the chain of particles with strong magnetic anisotropy weakens the thermal effect of hyperthermia under the effect of easy magnetization axes of ferro-nanoparticles. © 2020 American Institute of Physics Inc.. All rights reserved.This paper has been supported by RFFI, grants 18-08-00178, 19-52-45001 and the state program of the Ministry of Science and Higher Education of the Russian Federation (theme “Magnet” and Contract No. 02.A03.21.006)