Studies on genetic variation within old Polish cultivars of common oat

The gene pool of Polish oat cultivars is quite narrow. Obsolete cultivars bred at the beginning of the 20th century could be one of the “new” sources of genetic diversity. Re-using them in breeding programs might be much easier than interspecific hybridization with wild relatives. The aim of this study was to assess genetic variation within cultivars bred in Poland before 1939. Molecular analysis was carried out using ISSR markers. The obtained results have shown the old cultivars are much more heterogenic than the advanced ones. Distinctiveness of the gene pool of these accessions in relation to the modern Polish cultivar and landrace was also observed. UPGMA analysis has shown, despite the considerable time lapse, the tested cultivars retain their genetic integrity. Based on archive pedigree data it was found that most of the analysed accessions had diverse origin. Low value of total genetic variation of the old cultivars collection may indicate the gene pool of the primeval oat forms which were brought and grown in Poland was quite narrow. Both breeding history and the results presented in this paper suggest the restoration of old cultivars to Polish breeding should be one of the main tasks of gene bank in the future. According to the monitoring of accession sharing conducted by the national gene bank, breeders’ interest in old cultivars and landraces was and still is neglected

Development of magnetorheological elastomers (MREs) for strength and fatigue resistance

Natural rubber (NR)-based magnetorheological elastomers (MREs) exhibiting a reasonable switching effect were fabricated and tested. They were strong enough for use in automotive applications but still needed protection against ageing. Ethylene–propylene–diene rubber (EPDM) is a cost-effective material that is frequently used in the automotive industry because of its advantageous range of properties. With these applications in mind, it was a logical progression to the development of EPDM-based MREs. Unlike strain-crystallising NR, EPDM requires reinforcement to render its tensile and fatigue strength suitable for use in most applications. While small amounts of carbon black were sufficient for the NR-based MREs, a trade-off between non-reinforcing carbonyl iron powder (CIP) and reinforcing carbon black fillers was necessary to imbue the EPDM-based MREs with reasonably good mechanical properties. With a limit on the quantities of fillers that could be added, attention was turned to the matrix material itself and the blend of polymers employed in EPDM2 and EPDM3 were chosen in order to strengthen the EPDM-based MREs by enhancing polymer molecular weight and reinforcement. However, an unwanted effect of the stronger polymer network was the high-viscosity matrix in these compounds which hindered the alignment of magnetic particles early in the vulcanisation process. This led to poorer magnetic particle orientation, resulting in a more homogenous dispersion of the CIP and consequently produced MRE specimens that were more isotropic than anisotropic. Subsequently the switching effect of these materials was lower than would be obtained in MREs with a low viscosity (say, 40 MU) matrix. It was not feasible to sacrifice reinforcing carbon black in these compounds, but there are other possibilities open to the rubber compounder. An alternative means of reducing the viscosity of EPDM3 is simply to double the content of softening oil. This would have a slight but minimal negative effect on the tensile properties of the material. The addition of a small amount of retardant to delay vulcanisation and extend the time available for orientation of the magnetic particles into chains would also be beneficial. This would also reduce the modulus of the compound, but the reduction would again be negligible. As in all material design, there is a trade-off to be made in choosing the right combination of properties, but both of these changes would result in the development of an effective magnetorheological compound

Rheological properties of magnetic biogels

We report an experimental and theoretical study of the rheological properties of magnetic biogels consisting of fibrin polymer networks with embedded magnetite nanoparticles, swollen by aqueous solutions. We studied two types of magnetic biogels, differenced by the presence or absence of an applied magnetic field during the initial steps of cross-linking. The experiments demonstrated very strong dependence of the elastic modulus of the magnetic biogels on the concentration of the magnetic particles. We finally developed some theoretical models that explain the observed strong concentration effects.This study was supported by projects FIS2013-41821-R (Plan Nacional de Investigación Científica, Desarrollo e Innovación Tecnológica, MINECO, Spain, co-funded by ERDF, European Union) and FIS2017-85954-R (Ministerio de Economía, Industria y Competitividad, MINECO, andAgencia Estatal de Investigación, AEI, Spain, co-funded by Fondo Europeo de Desarrollo Regional, FEDER, European Union). A.Z. is grateful to the program of the Ministry of Education and Science of the Russian Federation, projects 02.A03.21.0006, 3.1438.2017/4.6, and 3.5214.2017/6.7, as well as to the Russian Fund of Basic Researches, project 18-08-00178

Different Localizations and Cellular Behaviors of Leiomodin and Tropomodulin in Mature Cardiomyocyte Sarcomeres

Lmod is a muscle-specific actin nucleator that displays structural similarity to the filament pointed-end–capping protein, Tmod. The mechanisms of localizations of Lmod and Tmod in muscle sarcomeres are strikingly different. Lmod contributes to the organization of mature myofibrils through a mechanism that requires interaction with tropomyosin

The effect of the surface modification of carbon nanotubes on their dispersion in the epoxy matrix

Functionalization of multi-walled carbon nanotubes (MWCNTs) has an effect on the dispersion of MWCNT in the epoxy matrix. Samples based on two kinds of epoxy resin and different weight percentage of MWCNTs (functionalized and non-functionalized) were prepared. Epoxy/carbon nanotubes composites were prepared by different mixing methods (ultrasounds and a combination of ultrasounds and mechanical mixing). CNTs modified with different functional groups were investigated. Surfactants were used to lower the surface tension of the liquid, which enabled easier spreading and reducing the interfacial tension. Solvents were also used to reduce the liquid viscosity. Some of them facilitate homogeneous dispersion of nanotubes in the resin. The properties of epoxy/nanotubes composites strongly depend on a uniform distribution of carbon nanotubes in the epoxy matrix. The type of epoxy resin, solvent, surfactant and mixing method for homogeneous dispersion of CNTs in the epoxy matrix was evaluated. The effect of CNTs functionalization type on their dispersion in the epoxy resins was evaluated on the basis of viscosity and microstructure studies

Porous ceramic - metal composites obtained by infiltration methods

A pressure-vacuum infiltration (T = 720 ºC, p = 15 MPa, t = 15 min) and gas-pressure infiltration (GPI) in an autoclave (T = 700ºC, p=4 MPa, t=5 min) were applied for infiltration of porous Al2O3 ceramics by cast aluminum alloy. Effect of the method of the infiltration on the microstructure and mechanical properties of ceramic-metal composites, was studied. Ceramic preforms were formed by method of copying the cellular structure of the polymer matrix. The results of the X-ray tomography proved very good infiltration of the pores by the metal for each method