PDL stops the rot
This item is not about ‘who’d’ve thought it?’, but is firmly in the ‘why would anybody think to try it out in the first place (but aren’t you glad they did!)?’ category.
Husnu Gerengi (Duzce University, Turkey) demonstrates that juice from the fruit of the date palm (Phoenix dactylifera – PDL) inhibits corrosion of aluminium alloy AA7075 in 3.5 % NaCl (the salt strength of ‘average’ seawater). The relevance of this is that the alloy is commonly used in body panels of the cooling system in cars, in hydrogen gas vessels with high-temperature applications, and in the aerospace industry (where you definitely don’t want metal bits corroding and dropping off of the aircraft – not when it’s up in the air anyway).
Although inorganic, anti-corrosion chemicals are used for aluminium alloys, they frequently contain chromates, which are highly toxic, as graphically demonstrated in the film Erin Brockovich. Safer, more environmentally benign solutions are therefore sought. Although date juice seems an unlikely thing to try, experimentation was inspired by anti-corrosion success of Hymn Rehan with leaf extract of PDL. Quite why Rehan was inspired to try out leaf extracts in this way is a mystery for another day (scrutiny of his paper doesn’t reveal the answer). Although date juice contains several sugars, Gerengi suggests that it is the glucose component that is adsorbed onto the aluminium’s surface and is the main component in the inhibitory effect.
[For more on this fascinating area of ‘green chemistry’ and corrosion-inhibition by plant extracts, why not try this review by Ambrish Singh et al. or this one by Joseph Buchweishaija? – Ed.]
Image: Wikimedia Commons.
Dates, the sticky, sweet fruits of the date palm (Phoenix dactylifera), are the product of sexual reproduction in that plant and borne on the female plants of this dioecious species. Globally, about 15 million metric tonnes of dates are produced annually from 100 million date palm trees and represent a staple food in many Middle Eastern and North African nations. Given this economic importance it is important to know if an individual tree is male or female. Up to now breeders have had to wait for 5 years before they could tell the sex of a tree. That process is likely to be speeded up dramatically with the discovery by Eman Al-Dous et al. (Nature Biotechnology; doi:10.1038/nbt.1860) of sequences of the genome that are linked to gender. The work, which represents the first genome sequence of a member of the palm family (Arecaceae) – and, indeed, of the higher taxonomic ranking, the order Arecales – has also identified genetic markers likely to facilitate breeding of traits such as superior fruit quality and more convenient ripening times into the best current cultivars. The group also propose that the date palm employs an XY system of gender inheritance, similar to that used by humans. In case you were wondering, parthenocarpy is known in this species, but the seedless fruit is smaller and of lower quality than the sexually produced product (http://en.wikipedia.org/wiki/Date_%28fruit%29#Food_uses).
Dioecy has evolved independently several times during the evolution of flowering plants, but knowledge of the mechanisms involved is poor. Phoenix dactylifera is a dioecious species displaying strong dimorphism between pistillate and staminate flowers, and Daher et al. (pp. 255–266) describe the transition of reproductive buds from a bisexual to a unisexual stage. They find that unisexuality of date palm flowers results from cell cycle arrest of sterile sex organs, rather than from cell death.