All plants contain varying levels of phenolic acids (metabolites) thus playing an important role in resistance mechanisms as constituents of cell walls, as constitutive antimicrobial compounds of plants or induced in response to infection against many diseases, in particular fusarium head blight caused by Fusarium species. To this end, the objective of this research was to study the variation in phenolic acid composition during the kinetics of filling wheat grains, in order to determine the best variety resistant to fusarium head blight. For this purpose, free and bound phenolic analyses were carried out by HPLC-DAD on five durum wheat varieties at the stage 5 to 8 days after the flowering stage (early grains). We showed that at the level of the samples analyzed, several phenolic acids were present at different concentrations, but others were absent [ cis-ferulic acid (free phenolic acid), and sinapic acid (bound phenolic acid)]. The results also showed that the content of bound phenolic acids was much higher than that of free phenolic acids in all varieties. In addition, these phenolic acids existed in free soluble form or were mostly present in insoluble form bound to cell walls. For free acids, the results showed that significant amounts of transferulic acid were detected in comparison to all free phenolic acids (56.72 μg · g ^–1 DM for G10). For bound acids, ferulic acid is the main bound phenolic acid which has much higher levels (4913.92 μg · g ^–1 DM for G1), followed by p-coumaric acid (3098.99 μg · g–1 DM for G1). Moreover, the sum of monomers (bound acids) was much higher than that of dehydrodiferulic acids (DiFA).

The article provides results of the microstructure examinations and mechanical properties (hardness and microhardness tests) of the welded joint T91 steel taken from the live steam pipeline. Examined joint has been exploited for about 45 000 hours in a temperature of 535oC and the steam pressure equals to 13.5 MPa. Examined joint was made as a double bead by the additional materials with a different chemical composition. It was proved that the joint was characterized by a differential microstructure on the cross-section of the weld. Moreover, decarburized zone in the lower alloyed material and carbides zone in the higher alloyed material were revealed in the weld line and on the boundary penetration of beads. Furthermore, it was shown that the main mechanism of a joint degradation is a privileged precipitation of carbides on the grain boundaries, and an increase of their size.

Research was conducted on welded joints of martensitic steel Thor 115 made with two filler materials – CrMo91 and Ni 6082. The scope of the investigations included: non-destructive and destructive testing. The macro- and microstructural investigations revealed correct structure of the weld, without welding imperfections. In the joint welded with Ni 6082, the so-called Nernst’s layers and δ-ferrite grains were visible. The investigations of the analysed joints showed that their properties, i.e. tensile strength and impact strength, were higher than the required minimum, whereas hardness was lower than the maximum value of 350 HV permitted for this group.