Resonance control of piezolaminated structures

This paper deals with a third order shear deformation finite element model wich is applied on the active resonance control thin plate/shell laminated structures with integrated piezoelectric layers of patches, acting as sensors and actuators. The finite element model is a single layer tringular nonconforming plate/shell element with 24 degrees of freedom for he generalized displacements, and one electrical potential degree of freedom for each piezoelectric element layer, wich are surface bonded on the laminated. The newwork method is considered to calculate the dynamic response of the laminated sructures forced to vibrate in the first natural frequency. To achieve a mechanism of active control of the structure dynamic response, a feedback control algorithm is used, coupling the sensor and active piezoelectric layers. The model is applied to the solution of one illustrative case, and the results are presented and discussed.

Germination requirements of Plantago algarbiensis seeds, an endangered species endemic to the Algarve region (South of Portugal)

The ecdysteroid, 20-hydroxyecdysone or beta-ecdysone, is a steroid hormone which plays a crucial role in molting, metamor- phosis and reproduction of arthropods. This ecdysteroid and its analogues have high potential to be used as insecticides. Previous studies in our laboratory have demonstrated that Vitex glabrata R.Br. (commonly known as Khai-Nao), an indigenous herbaceous plant of Thailand, synthesized and accumulated high quantity of 20-hydroxyecdysone. Therefore, the aim of this study was to investigate the effect of precursor and elicitors feeding on cell growth and 20-hydroxyecdysone production of V. glabrata suspension cultures. Plant cells were cultured in half strength MS medium containing 30 g/l glucose and supplemented with 2.0 mg/l 6- benzylaminopurine (BAP) and 1.0 mg/l 2,4-dichlorophenoxyacetic acid (2,4-D). Cells were incubated on a rotary shaker at 120 rpm under continuous light of 2000 lux at 25 °C. Sterilized cholesterol (5 and 10 mg/l) as precursor was added to the cell cultures on the day of inoculation, while chitosan (50, 100 and 200 mg/l) and methyl jusmonate (100 and 200 mM) as elicitors were added to the cell cultures on day 6 after cultivation.