A low‐strain domain has been identified in the metamorphosed, mostly highly deformed volcanic and sedimentary rocks of the early Archaean Isua supracrustal belt. This domain contains well‐preserved volcanic and sedimentary features, including basaltic pillow lavas, pillow breccia, heterogeneous volcanic breccia, amygdules in metabasalt, and polymict conglomerate dominated by recrystallized chert and volcanic clasts. The low‐strain domain is bounded by highly deformed rocks mostly derived from basalt, chert, and banded iron formation. These discoveries demonstrate that some primary features have escaped the pervasive metasomatism dominant in other parts of the belt and, furthermore, strengthen the characterization of the Isua supracrustals as a typical greenstone belt.

The first part of the paper presents an accompanying investigation to a thermomechanical processing route of gamma-TiAl turbine blades. By means of scanning electron microscopy and energy dispersive X-ray (EDX) analysis, the chemical homogeneity and the microstructures of gamma-TiAl as-cast ingots, work pieces and the final turbine blades are determined. We find that the local Al-content in as-cast ingots can vary by more than 1.5 at.%. Large chemical inhomogeneities present in as-cast ingots can only be eliminated to a certain degree by subsequent thermomechanical processing. An additional aim of the study is to assess the influence of a thermomechanical processing on the morphology of titanium boride precipitates and the alpha2-Ti3Al-phase. The second part of the paper contains a detailed analytical study devoted to homogenization of a range of gamma-TiAl cast alloys. Different microstructures are generated in a laboratory-scale argon-arc furnace by both rapid and slow solidification rates and an additional homogenization treatment, respectively. Quantitative EDX analysis shows that only rapid solidification of ingots with a subsequent homogenization treatment leads to a nearly chemically homogeneous microstructure.

This article contains a detailed description of a reliable method for the inoculation of potato tubers with Phytophthora infestans. This technique was developed as a general basic method for greenhouse and field trials to study the development of the primary inoculum source in potato crops. It was applied to increase the reproducibility of infections from tubers to sprouts. Afterwards the pathogen was detected in light sprouts and stems at different stadiums of plant growth by the polymerase chain reaction‐based test (PCR). From this it follows that Phytophthora infestans is able to grow directly up into the stem from the tuber as mycelium. In the course of plant growth the concentration of mycelium fell below the detection limit in some of the assayed stems on account of dilution effects, although the symptoms occurred in the following period. Apparently the pathogen is also able to cause symptoms in the plant at very low concentrations.

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