ABSTRACT
The impact of temperature on the pulsed magnetization of a high-temperature superconductor (HTS) has been numerically studied. The resulting trapped field (TF) and its distribution over the HTS have been calculated for samples with random and periodic pinning (a regular triangular lattice). The increasing ambient temperature (within the considered values) has been shown to improve the field-trapping efficiency and lead to the possibility of pumping more flux into the sample with each consecutive pulse (contrary to the low-temperature case). Various pulse shapes produced different results at high temperatures. Trapezoidal pulses showed the highest efficiency owing to the constant-field segments during which the vortices continued to enter the sample. The critical (activation) field of flux jumps has been shown to decrease with the rising temperature. At the highest considered temperature (30 K), the flux jumps occurred during the TF relaxation. To the best of our knowledge, such calculations have been done for the first time.
ABSTRACT
By means of the Monte Carlo method, a numerical study of the vortex system in a high-temperature superconductor under the impact of pulses of magnetic field has been conducted. Various shapes and amplitudes of pulses have been considered. Samples with random and regular distributions of three different numbers of defects have been compared from the viewpoint of efficiency of flux trapping. The low-temperature behavior of vortices and their penetration into samples have been shown to be independent of the pulse shape but strongly dependent of the type of pinning distribution. Saturating dependences of density of trapped magnetic flux on the pulse amplitude have been obtained. The samples with random pinning demonstrated higher efficiency of flux trapping at lower pulse amplitudes, and the samples with a triangular lattice of defects-at higher amplitudes. If the amplitude exceeded the saturation field of both samples, the trapped field was almost equal. The increasing number of defects has lead to an increase in trapped field within the considered range of concentrations.
ABSTRACT
A computer-aided analysis of the repeating sequence of Bordetella pertussis chromosome (RSBP3) revealed 3 open reading frames, one of whose (ORF1) can code a protein whose structure and properties are similar to those of transposasas, i.e. enzymes in charges for the traveling of migrating genetic elements of pro- and eukaryote. Mutants of the RSBP3 insertion sequence with the affected and unaffected ORF1 sequence were constructed in order to substantiate the above assumption. Two independent experimental models (formation of inter-plasmid co-integrates and of co-integrates between plasmid and E. coli chromosome) were used to show that the RSBP3-stimulated formation of co-integrates is only true for plasmids containing RSBP3 with the unaffected ORF1 sequence. An activity of the Hpr protein (a component of the phosphoenolpyruvate-dependent phosphotransferase) was proven to influence the formation process of inter-plasmid co-integrates.
Subject(s)
Bordetella pertussis/genetics , Open Reading Frames , Transposases/genetics , Bacterial Proteins/physiology , Bordetella pertussis/enzymology , Chromosomes, Bacterial , Computers , Phosphoenolpyruvate Sugar Phosphotransferase System/physiology , Plasmids , Repetitive Sequences, Nucleic AcidABSTRACT
Two types of proteolytically cleaved influenza virus nucleoprotein (NP) are formed in cells infected with influenza virus. One, cell membrane-associated cleaved NP (C-NP), is heterogeneous in size and during analysis in PAGE is localized in the 53 kDa and less zone. Its formation depends on the species appurtenance of the infective virus and occurs only in viruses with a low efficacy of NP oligomerization. C-NP is incapable of intracellular oligomerization. The other type of cleaved NP, extracellular free (F-NP), is most likely a secreted product of intracellular proteolysis of 56 kDa NP. Its molecular weight is about 53 kDa. Its formation does not depend on the species of infective influenza virus and it is capable of intracellular oligomerization.
Subject(s)
Influenza A virus/physiology , Nucleoproteins/metabolism , RNA-Binding Proteins , Viral Core Proteins/metabolism , Animals , Biopolymers , Cell Line , Dogs , Electrophoresis, Polyacrylamide Gel , Hydrolysis , Nucleocapsid Proteins , Nucleoproteins/isolation & purification , Protein Processing, Post-Translational , Viral Core Proteins/isolation & purificationABSTRACT
The plasmid pSS120, determining the synthesis of species specific I phase antigen of Shigella sonnei is mobilized for genetic transfer into E. coli K12 recipient cells with the frequency 12-41%. The frequency depends on the type of mobilized plasmid and recipient strain. The I phase antigen is normally expressed in II phase recipient cells and in E. coli cells. During mobilization pSS120 forms cointegrates representing a recombinant of mobilizing and mobilized plasmids DNA. The study of pSS120 inheritance stability has shown the plasmid to be unstable during culturing of bacteria and to be partially lost from the parent Shigella sonnei strains as well as from the "hybrid" transconjugants obtained. The 60 Md plasmid present in the donor strains of Shigella sonnei is prone to structural fragmentation particularly expressed in Shigella sonnei/E. coli hybrids.
