Oligomerization of Dicyclopentadiene Fraction Using Monosubstituted Titanium Chloride as a Catalyst

The purpose of this study is to investigate the dicyclopentadiene fraction of liquid pyrolysis product oligomerization with the use of the modified catalytic system based on titanium alkoxides. The choice of reaction catalyst is specified by searching the ways of obtaining petroleum resins with the improved performance characteristics and the possibility of low-temperature polymerization. The use of monosubstituted titanium chloride as a catalyst allows obtaining light resins, films on the base of which are smooth, glossy and have good technical characteristics: adhesion 1 point, resilience 10 cm

Cryptanalysis the SHA-256 Hash Function using Rainbow Tables

The research of the strength of a hashed message is of great importance in modern authentication systems. The hashing process is inextricably linked with the password system, since passwords are usually stored in the system not in clear text, but as hashes. The SHA-256 hash function was chosen to model the attack with rainbow tables. An algorithm for constructing a rainbow table for the SHA-256 hash function in the Java language is proposed. The conditions under which the use of rainbow tables will be effective are determined. This article aims to practically show the process of generating a password and rainbow tables to organize an attack on the SHA-256 hash function. As research shows, rainbow tables can reveal a three-character password in 3 seconds. As the password bit increases, the decryption time increases in direct proportion

Algebraic algorithms for multiloop calculations. The first 15 years. What's next?

The ideas behind the concept of algebraic ("integration-by-parts") algorithms for multiloop calculations are reviewed. For any topology and mass pattern, a finite iterative algebraic procedure is proved to exist which transforms the corresponding Feynman-parametrized integrands into a form that is optimal for numerical integration, with all the poles in D-4 explicitly extracted.Comment: 5 pages, PS; 7-11-98: maintenance (PS, misprints, etc.

Influence of vehicle emissions on the male generative system of <i>Aesculus hippocastanum</i> L.

The article presents the results of a study of the impact of vehicle emissions on populations of Aesculus hippocastanum L. growing along roads with different traffic intensities. It was found that in areas of heavy vehicle traffic there is an increased level of abortive pollen production. Plant populations increasing the formation of damaged gametes with increasing anthropogenic load on phytocoenoses can be used for phytoindication of the environmental pollution degree. In areas with heavy traffic, pollutants have an average toxic effect on the gametogenesis of Aesculus hippocastanum L. The quality and degree of damage to the pollen zone formed by plants can serve as a bio-test of the mutagenic effect of environmental factors that have a modifying effect on male gametophyte of higher plants.</jats:p

Two-dimensional current-carrying plasma sheet in the near-Earth geomagnetic tail region:<br>a quasi-stationary evolution

A problem concerning stationary configurations of an inhomogeneous, current-carrying, two-dimensional plasma sheet as the solution of the Grad–Shafranov equation with boundary conditions given on cross-sheet profiles at the&nbsp; foot of the sheet and at infinity is considered, with the aim of using its solution for the description of the interaction of two current systems: the current system of the geomagnetic field, and the tail currents. The obtained solution is an exact analytical solution which contains 5 independent parameters characterizing the intensity of the current sheet. As the solution is exact, it may be applied to describe the most interesting transitional magnetospheric region: that of a strong interaction between the magnetic fields of the geodipole and of the current sheet, i.e. the region where characteristic scales of the change of all variables along and across the sheet are of the same order. This makes it possible to model the structure of the transitional region and its dynamics under quasi-stationary variation of the input parameters. The obtained solution describes the principal processes developing at various phases of magnetospheric disturbances, such as (1) formation of a very intense thin current sheet localized within the transition region, (2) changing from the quasi-dipolar magnetic field to the configuration when a "neck" is formed in this region. An important feature of the obtained solution is the existence of a critical value of one of the parameters of the problem, which leads to the change in the geomagnetic field configuration described above. The solution can be used as an initial condition in simulating dynamical processes in the magnetotail current sheet, as well as in testing the current sheet stability. In the summary a series of limitations in the model problem under consideration is discussed.&nbsp;<br><br><b>Key words.</b> Magnetospheric physics (magnetotail; plasma sheet; magnetospheric configuration and dynamics

Influence of vehicle emissions on the male generative system of

The article presents the results of a study of the impact of vehicle emissions on populations of Aesculus hippocastanum L. growing along roads with different traffic intensities. It was found that in areas of heavy vehicle traffic there is an increased level of abortive pollen production. Plant populations increasing the formation of damaged gametes with increasing anthropogenic load on phytocoenoses can be used for phytoindication of the environmental pollution degree. In areas with heavy traffic, pollutants have an average toxic effect on the gametogenesis of Aesculus hippocastanum L. The quality and degree of damage to the pollen zone formed by plants can serve as a bio-test of the mutagenic effect of environmental factors that have a modifying effect on male gametophyte of higher plants

Assessment of the effect of aerotechnogenic pollution on male reproductive organs <i>Convolvulus arvensis</i> L.

The article presents the results of assessing the impact of airtechnogenic pollution on the male generative organs of Convolvulus arvensis L. The unfavorable effect of toxic emissions from the landfill of municipal solid waste and vehicles on the processes of microsporogenesis of the populations of Convolvulus arvensis L., which was expressed in the production of large abortive pollen, was established. It is recommended to use the male generative system of the populations of Convolvulus arvensis L. for bioindication of the quality of the state of the environment.</jats:p