Wyniki wyszukiwania - Biblioteka Nauki

Nowa wersja platformy, zawierająca wyłącznie zasoby pełnotekstowe, jest już dostępna.
Przejdź na https://bibliotekanauki.pl

Ograniczanie wyników

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

Multiple generational cloning of livestock embryos

100%

Piotrowska K. , Modlinski J.

Biotechnologia

1998

nr 2

130-136

The main purpose of nuclear transfer in domestic species is to produce a large number of identical animals. There are two main ways to produce clones by nuclear transfer. One is to use the ICM and ED cells cultured under special conditions, as donor nuclei. The other way is to use the nuclear transfer embryo itself as the donor for the next generation of cloning (multiple generational cloning). The in vitro and in vivo developmental ability of nuclear transferred embryos is the same in the case of the first three generations. A limited number of multiple-generation clones were transferred into recipient heifers, resulting in offspring from I, II and III generation clones. The strategy to increase the efficiency of multiple generational bovine embryo cloning is discussed as well as the possible use of rabbit embryos as an experimental model.

Structure and Physicomechanical Properties of Nanostructured (TiHfZrNbVTa)N Coatings after Implantation of High Fluences of N⁺ (10¹⁸ cm¯²)

70%

Pogrebnjak A. , Bondar O. , Borba S. , Piotrowska K. , Boiko O.

Acta Physica Polonica A

2017

tom 132

nr 2

217-221

New classes of high-entropy alloys, which consist of at least 5 main elements with atomic concentrations 5-35 at.%, are under great interest in modern material science. It is also very important to explore the limits of resistance of high-entropy alloy nitrides to implantation by high-energy atoms. Structure and properties of nanostructured multicomponent (TiHfZrNbVTa)N coatings were investigated before and after ion implantation. We used the Rutherford backscattering, scanning electron microscopy with energy dispersive X-ray spectroscopy, high resolution transmission electron microscopy and scanning transmission electron microscopy with local microanalysis, X-ray diffraction and nanoindentation for investigations. Due to the high-fluence ion implantation (N⁺, the fluence was 10¹⁸ cm¯²) a multiphase structure was formed in the surface layer of the coating. This structure consisted of amorphous, nanocrystalline and initial nanostructured phases with small sizes of nanograins. Two phases were formed in the depth of the coating: fcc and hcp (with a small volume fraction). Nitrogen concentration reached 90 at.% near the surface and decreased with the depth. Nanohardness of the as-deposited coatings varied from 27 to 34 GPa depending on the deposition conditions. However, hardness decreased to a value of 12 GPa of the depth of the projected range after ion implantation and increased to 23 GPa for deeper layers.