Oxine sorption by binary mixtures of montmorillonite and silica gel was studied at pH 5 as a function of oxine concentration and mixture composition. The investigation was made to resolve the problem of the determination of the oxine sorbed by each substance, inasmuch as the total amount sorbed by the mixture is the only value accessible experimentally. By the application of the thermodynamic method of partial quantities, the apparent and partial specific sorption by the clay and by the gel were calculated. These sorption values were found to increase with oxine concentration and to decrease as the proportion of the clay increased in the mixtures.

Several elicitors, stimulating induced resistance mechanisms, have potential in preventing or mitigating pathogen infections. Some of these compounds, triggering the production of jasmonic acid (JA), a precursor of herbivore-induced plant volatiles, could also play a central role in indirect resistance to pest species, by improving beneficial arthropod performance, and necrotrophic pathogens. In the current work, Trichoderma gamsii/T. asperellum and silica gel treatments – alone and in combination – were studied to evaluate the plant defence mechanism on grapevines (Vitis vinifera L.) by laboratory and field trials. JA production level was measured before and after Plasmopara viticola infection on potted vines. JA production induced by silica gel was higher than that caused by Trichoderma before infection. In Trichoderma-treated plants, JA production increased after P. viticola inoculation. In vineyard field trials, Mymaridae (Hymenoptera: Chalcidoidea) showed higher captures in transparent sticky traps on silica gel-treated plants, in comparison with control. On the other hand, no significant attraction was detected for Ichneumonoidea and other Chalcidoidea in silica gel and T. gamsii/T. asperellum-treated plants. The potential effects of elicitors are discussed, in the frame of attract and reward strategy.

The function of acid-activated sepiolite clay was evaluated for use in the clarification of apple juice. Optimizing the clarification process was done using response surface methodology (RSM) considering juice turbidity as a response. The efficiency of sepiolite in terms of clarification was compared to that of bentonite and a combination of these fining agents with gelatin and silica gel at optimal conditions. The conditions of 0.05% clay concentration at a temperature of 50°C for 7 h were deemed optimal in terms of juice clarification. The present results showed that treatment of sepiolitegelatin-silica gel was the most active fining agent with 99.7% reduction in apple-juice turbidity. The rate of turbidity, the viscosity, the total phenolic contents and the colour changes were fitted to first-, zero-, first- and zero-order kinetic models, respectively.

Wax filaments > 100 μm long on the epidermis of johnsongrass leaves and culms occurred only around the edge of costal cork-silica cell pairs and intercostal silica cells. Silica cells alternating with cork cells occurred in rows over veins. Solitary or occasionally paired cork-silica cells occurred between veins. The high silicon content of silica cells was verified with X-ray mapping of silicon. X-ray analysis also indicated that wax filaments contained silicon. Scanning electron micrographs (SEM) of dislodged intercostal silica cells showed that wax filaments emerged from an integument that surrounded the silica cell. It is theorized that at high ambient temperatures the silica gel in silica cells provides the localized cooling necessary to solidify liquid wax constituents as they are extruded onto the surface of the plant.