Microstructure and mechanical properties of Nb15Al10Ti alloy produced by mechanical alloying and high temperature processing.

In this work, an Nb15Al10Ti alloy produced by mechanical alloying was investigated. The milling of elemental powders of Nb, Al as well as TiAl intermetallic phase resulted in the formation of homogenous niobium solid solution, Nb(ss), and refinement of powder particles. Powder after milling was consolidated by conventional hot pressing at 1300 degrees C under pressure of 25 MPa as well as by hot isostatic pressing at 1200 degrees C under pressure of 1 GPa. Microstructure of consolidated material was examined by transmission electron microscopy, scanning electron microscopy and X-ray diffraction. Materials after consolidation were composed of three phases: niobium solid solution Nb(ss), Nb(3)Al intermetallic phase and titanium oxide dispersoid TiO. The analysis of the mechanical properties indicated that both refinement of microstructure as well as introduction of ductile Nb(ss) into the microstructure contributed to very high yield strength and fracture toughness satisfactory for this strength.

[Determination of the concentration of chorionic gonadotropin (HCG) and its free subunits in placental tissue during various periods of normal pregnancy]. / Die Konzentrationsbestimmung des Choriongonadotropin (HCG) und seiner freien Untereinheiten im Plazentagewebe in verschiedenen Perioden der normalen Schwangerschaft.

The aim of this study was to estimate HCG and its free subunits (alpha and beta) content in placental tissue and to determine the characteristic pattern of their ratio changes in the course of normal pregnancy. For this we used 47 samples of placental extracts. The tissue was extracted and gel filtrated on a calibrated Sephadex-G-100 column. Crude placental extracts and each fraction after chromatography were radioimmunoassayed for HCG, alpha HCG and beta HCG in a double antibody, homologous radioimmunoassay system. We obtained the following results: Peak of native HCG secretion occurred in 6-8 gestational week thereafter its concentration in placenta decreases. The absolute amount of free alpha HCG increased after the first trimester like to native HCG, but the relative quantity of alpha HCG exceeded that for HCG. In extracts from mature placenta quantity of free alpha HCG was about 5-10-fold more than HCG. In chorionic extracts from the first trimester we have proved the free beta subunit of HCG. It has not been found in extracts from mature placenta.

[Role of detection of alphafoetoprotein in serum of pregnant women with risk of abortion (author's transl)]. / Zur Wertigkeit des alpha-Fetoprotein-Nachweis im Serum von Schwangeren mit drohendem Abort.

Alpha, foetoprotein (AFP) was radio-immunologically determined in the serum of 109 pregnant women with imminent abortion and of 220 clinically intact women who were between the sixth and 22nd weeks of pregnancy. -- AFP values were found to be normal, within limits between 0.5 m and 2.0 m, in 84.8 per cent of the clinically intact women and in 83.3 per cent of those pregnant women with imminent abortion and favourable completion of pregnancy. Values were above or below normal in 73.3 per cent of those pregnant women who failed to complete pregnancy with good success.