Under any prescribed electromechanical

loading, the volume fraction of each domain in a grain is obtained by minimizing the sum of the potential energy and switching the related dissipation energy of the whole grain using the sequential quadratic programming optimization algorithm. Similar to the phase field model, this model also does not require the imposition of any a priori domain-switching criterion. The computational efficiency of this model is fairly high and it is feasible to study 3-D cases using numerous grains. The domain texture evolution process can also be calculated step by step and shown using the pole figures of the polar axis. Simulation results on the morphotropic lead titanate zirconate ceramics under uniaxial electromechanical loading show that with the increase of the Wnt inhibitor uniaxial compression, both the D-E hysteresis loops and the butterfly curves becomes more flat and the electric coercive field becomes less distinct, which is in good agreement with existing experimental results. The calculated domain-texture evolution process indicates that when the compression is large enough, the domains have been constrained with their polar axis aligned JQ-EZ-05 order in those planes nearly perpendicular to the compressive direction and almost cannot switch under moderate electric loading, thus leading to

the more flat D-E hysteresis loops and butterfly curves. (C) 2011 American Institute of Physics. [doi:10.1063/1.3569583]“
“We have investigated photosynthetic changes of fully expanded pea leaves infected systemically Selleck ARN-509 by pea enation mosaic virus (PEMV) that often attacks legumes particularly in northern temperate regions.

A typical compatible virus host interaction was monitored during 40 post-inoculation days (dpi). An initial PEMV-induced decrease in photosynthetic CO2 assimilation was detected at 15 dpi, when the virus appeared in the measured leaves. This decrease was not induced by stomata closure and corresponded with a decrease in the efficiency of photosystem II photochemistry (Phi(PSII)). Despite of a slight impairment of oxygen evolution at this stage, PSII function was not primarily responsible for the decrease in Phi(PSII). Chlorophyll fluorescence imaging revealed that Phi(PSII) started to decrease from the leaf tip to the base. More pronounced symptoms of PEMV disease appeared at later stages, when a typical mosaic and enations appeared in the infected leaves and oxidative damage of cell membranes was detected. From 30 dpi, a degradation of photosynthetic pigments accelerated, stomata were closing and corresponding pronounced decline in CO2 assimilation was observed. A concomitant photoprotective responses, i.e. an increase in non-photochemical quenching and accumulation of de-epoxidized xanthophylls, were also detected.