37 research outputs found
Nanocrystalline Zr3Al Made through Amorphization by Repeated Cold Rolling and Followed by Crystallization
The intermetallic compound Zr3Al is severely deformed by the method of
repeated cold rolling. By X-ray diffraction it is shown that this leads to
amorphization. TEM investigations reveal that a homogeneously distributed
debris of very small nanocrystals is present in the amorphous matrix that is
not resolved by X-ray diffraction. After heating to 773 K, the crystallization
of the amorphous structure leads to a fully nanocrystalline structure of small
grains (10 - 20 nm in diameter) of the non-equilibrium Zr2Al phase. It is
concluded that the debris retained in the amorphous phase acts as nuclei. After
heating to 973 K the grains grow to about 100 nm in diameter and the compound
Zr3Al starts to form, that is corresponding to the alloy composition
Follicular fluid content and oocyte quality: from single biochemical markers to metabolomics
The assessment of oocyte quality in human in vitro fertilization (IVF) is getting increasing attention from embryologists. Oocyte selection and the identification of the best oocytes, in fact, would help to limit embryo overproduction and to improve the results of oocyte cryostorage programs. Follicular fluid (FF) is easily available during oocyte pick-up and theorically represents an optimal source on non-invasive biochemical predictors of oocyte quality. Unfortunately, however, the studies aiming to find a good molecular predictor of oocyte quality in FF were not able to identify substances that could be used as reliable markers of oocyte competence to fertilization, embryo development and pregnancy. In the last years, a well definite trend toward passing from the research of single molecular markers to more complex techniques that study all metabolites of FF has been observed. The metabolomic approach is a powerful tool to study biochemical predictors of oocyte quality in FF, but its application in this area is still at the beginning. This review provides an overview of the current knowledge about the biochemical predictors of oocyte quality in FF, describing both the results coming from studies on single biochemical markers and those deriving from the most recent studies of metabolomic