Влияние молекулярной массы на процесс электроформования волокнистых материалов, полученных из растворов полиакрилонитрила

In the article influence of the molecular weight of polyacrylonitrile on electrospinning process and also on the diameter and mechanical properties of the obtained fibers and fiber materials are considered. Polymers with molecular weight from 280 000 to 700 000 were investigated. Fibers with a diameter from 200 to 1100 nm were obtained.В статье рассматривается влияние молекулярной массы полиакрилонитрила на диаметр и механические свойства полученных волокон и волокнистых материалов. Исследованы полимеры с молекулярной массой от 280 000 до 700 000. Получены волокна с диаметром от 200-1100 нм

Исследование процесса растяжения жидкой полимерной струи в электрическом поле из растворов полиакрилонитрила

The article considers stretching of liquid polyacrylonitrile jet in electrostatic field. Polymers with molecular weight from 130 000 to 700 000 were investigated. Regularities of stretching of the jet based on polyacrylonitrile solutions were determined.В статье рассматривается процесс растяжения жидкой полимерной струи растворов полиакрилонитрила (ПАН) находящейся в электрическом поле. Исследованы полимеры с молекулярной массой от 130 000 до 700 000. Установлены основные закономерности процесса растяжения струи на основе растворов ПАН

Модельные характеристики кардиореспираторной системы высококвалифицированных гребцов на байдарках и каноэ

The most frequently used approach for protein structure prediction is currently homology modeling. The 3D model building phase of this methodology is critical for obtaining an accurate and biologically useful prediction. The most widely employed tool to perform this task is MODELLER. This program implements the "modeling by satisfaction of spatial restraints" strategy and its core algorithm has not been altered significantly since the early 1990s. In this work, we have explored the idea of modifying MODELLER with two effective, yet computationally light strategies to improve its 3D modeling performance. Firstly, we have investigated how the level of accuracy in the estimation of structural variability between a target protein and its templates in the form of σ values profoundly influences 3D modeling. We show that the σ values produced by MODELLER are on average weakly correlated to the true level of structural divergence between target-template pairs and that increasing this correlation greatly improves the program's predictions, especially in multiple-template modeling. Secondly, we have inquired into how the incorporation of statistical potential terms (such as the DOPE potential) in the MODELLER's objective function impacts positively 3D modeling quality by providing a small but consistent improvement in metrics such as GDT-HA and lDDT and a large increase in stereochemical quality. Python modules to harness this second strategy are freely available at https://github.com/pymodproject/altmod. In summary, we show that there is a large room for improving MODELLER in terms of 3D modeling quality and we propose strategies that could be pursued in order to further increase its performance

Optimization of protein structure on lattices using a self-consistent field approach

This is a copy of an article published in the Journal of Computational Biology ©1998 Mary Ann Liebert, Inc.; Journal of Computational Biology is available online at: http://www.liebertonline.com.Lattice modeling of proteins is commonly used to study the protein folding problem. The reduced number of possible conformations of lattice models enormously facilitates exploration of the conformational space. In this work, we suggest a method to search for the optimal lattice models that reproduced the off-lattice structures with minimal errors in geometry and energetics. The method is based on the self-consistent field optimization of a combined pseudoenergy function that includes two force fields: an "interaction field," that drives the residues to optimize the chain energy, and a "geometrical field," that attracts the residues towards their native positions. By varying the contributions ofthese force fields in the combined pseudoenergy, one can also test the accuracy of potentials: the better the potentials, i.e., the more accurate the "interaction field," and the smaller the contribution of the "geometrical field" required for building accurate lattice model

Modelling the Connection Between Earthquake Preparation Processes and Crustal Electromagnetic Emission

The steadily increasing amount of information available today on the natural electromagnetic emission (EME) of the radio frequency band associated with seismic events raises the problem of the origin of this phenomenon. A natural hypothesis is that EME is due to earthquake preparation processes. The present paper is concerned with substantiating a model that postulates EME to be caused by cracking of surficial crustal layers in the zone of earthquake preparation. The crust is assumed to have ordered hierarchical structure. Individual elements of that structure are formed of blocks of different scales and obey principles of similarity. Between the blocks are soft interlayers with a finite strength limit. A regular periodic structure with a cubic lattice is studied. As a result, EME intensity as a function of magnitude is evaluated. Methodological recommendations are given for organization of field observations of EME in relation to earthquake prediction

Influence of molecular weight on electrospinning of fiber materials obtained from solutions of polyacrylonitrile

In the article influence of the molecular weight of polyacrylonitrile on electrospinning process and also on the diameter and mechanical properties of the obtained fibers and fiber materials are considered. Polymers with molecular weight from 280 000 to 700 000 were investigated. Fibers with a diameter from 200 to 1100 nm were obtained

Modelling the Connection Between Earthquake Preparation Processes and Crustal Electromagnetic Emission

The steadily increasing amount of information available today on the natural electromagnetic emission (EME) of the radio frequency band associated with seismic events raises the problem of the origin of this phenomenon. A natural hypothesis is that EME is due to earthquake preparation processes. The present paper is concerned with substantiating a model that postulates EME to be caused by cracking of surficial crustal layers in the zone of earthquake preparation. The crust is assumed to have ordered hierarchical structure. Individual elements of that structure are formed of blocks of different scales and obey principles of similarity. Between the blocks are soft interlayers with a finite strength limit. A regular periodic structure with a cubic lattice is studied. As a result, EME intensity as a function of magnitude is evaluated. Methodological recommendations are given for organization of field observations of EME in relation to earthquake prediction