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For the design of a magnetoelastic device for force measurements in tendons of prestressed concrete structures, magnetic and magnetoelastic measurement data of the BH-normal induction curve were determined for three prestressing steel specimens using a NPL-permeameter. These data were compared to three saturation models known from the literature: the linear (LSL), the quadratic (QSL) and the square-root (RSL) saturation law. The LSI, which was found to be the most suitable of them, is magnetoelastically generalized to the extended linear saturation law (ELSL). The magnetoelastic magnetization data of three selected prestressing steel specimens agree well with the ELSL-model equation. Model parameters, mechanical data and chemical composition of the three specimens are given.

In order to evaluate the role of aminopeptidases (APs) in drought response and their potential as protein markers to distinguish between stress tolerant and sensitive varieties, various AP activities were studied in roots and leaves of winter wheat seedlings, subjected to severe but recoverable soil drought stress. Two varieties with contrasting drought tolerance - Yantar (drought tolerant) and Miziya (sensitive) were compared. Activity changes under severe water stress and subsequent recovery were related to changes in the pools of the major redox buffers ascorbate and glutathione, changes in protein profiles and total proteolysis in roots and leaves. Glutathione was responsive to drought both in roots and leaves, with increased total pool and transient rise in the oxidized form; stronger response in the roots of Yantar was observed. The sensitive variety had higher ascorbate content in leaves under stress. Severe drought led to reversible changes in protein profiles and increase in major protease bands in leaves but not in roots. AP activities were partly independent from the predominant endoprotease activities. Highest activities in roots were detected with substrates releasing terminal leucine, lysine and metionine. In stressed leaves AP activities toward most of the substrates increased under drought, without clear differences comparing varieties. Activities tested with Gly-pNA were raised in leaves only in recovery from stress. In roots, the tolerant variety Yantar presented increased AP activities under stress with most of the substrates used except Leu-pNA and Phe-pNA, whereas the sensitive variety Miziya had almost unchanged AP activities. Based on activity profile changes, at least two different AP enzymes should exist in wheat. It remains to be established which activities towards different substrates reflect distinct aminopeptidases. [ABSTRACT FROM AUTHOR]

More frequent and more severe extreme events (e.g. flooding, drought, heat waves) were predicted from climate models for the next decades. Impacts of such events are relevant for crop productivity. Effects on a whole-plant level are the focus of this study. The influence of an extended drought period on solute allocation via the phloem was compared in two Bulgarian wheat varieties differing in drought susceptibility: "Sadovo" (drought-sensitive) and "Katya" (drought-tolerant). Young plants grown hydroponically on standard nutrient solution were transferred at the beginning of the experiment tofresh medium (controls) or to medium with polyethylene glycol 6000 (artificial drought). Radiolabeled solution (57Co, 109Cd, 134Cs) was introduced via a flap into the lamina of the third or fourth leaf of young plants (youngest fully expanded leaf before stress treatment). Export and allocation of the radiolabel were monitored by gamma spectrometry. 57Co, 109Cd and 134Cs are suitable radionuclides, since they are not metabolized and not released in gaseous form. The exported radionuclides were mainly found in the roots (30-50%) and in the younger leaves (30-60%), while only traces reached the older leaves indicating that only small quantities were transported back from the roots to the shoot via the xylem. A comparable percentage was transported from leaf 4 to leaves 5 and 6 in both varieties under control conditions. A much higher percentage was found in leaf 5 than in leaf 6 of "Katya" subjected to drought, while "Sadovo" was affected in the opposite direction. The results suggest that adaptations in the source/sink network are important for the drought susceptibility of wheat varieties. [ABSTRACT FROM AUTHOR]