Friday, March 30, 2018

When to drop the “ad” and “ab” prefixes

The prefixes ad and ab are generally used with the meaning toward and away from, respectively. But not within every context is the meaning and distinction that clear. An interesting example comes with the terms adsorption and absorption—near homophones. The noun adsorption refers to the attraction of something toward the interface of an object, while absorption means that something has been drawn into the bulk of the object through the interface. But where does the interface end and where does the bulk begin? And what if the subject of interest is found both at the interface and inside the object?

Adsorption and absorption phenomena are studied in physical chemistry. They play a key role in many chemical engineering processes. Chemical species such as neutral molecules and ions may stick to a material surfaces and/or diffuse deeper into the substrate material. Robert Kunin, who worked in the field of ion exchange, thoughtfully elaborated on the “ad-versus-ab controversy” in the 1950s:  
If we consider adsorption processes strictly as confined to changes occurring at an interface or surface and absorption as those processes involving solids engulfing substances throughout their entire structure, then ion exchange phenomena may fall into both categories and might therefore be more safely considered as a sorption process, a term that avoids the controversy between the devotees of the ad and ab prefixes. --- [Robert Kunin, 1958].

Kunin elected to use the term adsorption within his book on ion-exchange resins, considering that “energy considerations of ion exchange are more closely related to true adsorptive processes.”

Often, your particular context will clarify whether to speak of  ad- or absorption. When in doubt or with excusable lack of commitment to detail, the unprefixed word sorption—as implied by Kunin—should be the word of choice. The expression “ad/ab-sorption” is possible, but may confuse more than help.

Keywords: terminology, prefix use, physicochemical vocabulary.



Robert Kunin: Ion Exchange Resins. John Wiley & Sons, Inc., New York, 1958 (Second Edition); page 5.

Saturday, March 10, 2018

What is the wood-wide web?

The expression wood-wide web is a play on the term world-wide web. Both terms refer to communication networks. But in the case of the wood-wide web, communication is non-digital: it is chemical. Trees and other plants are able to send signals and communicate via airborne substances including hormones. In addition to wireless communication, forest trees share information and resources through wired underground root systems in cooperation with networks of mycorrhizal fungi.

Richard Grant recently wrote about the complex life of trees in a Smithsonian article [1].  He met with Peter Wohlleben—a German logger-turned-forest-conservationist, who is known for his book The Hidden Life of Trees: What They Feel, How They Communicate. Therein, Wohlleben describes the wood-wide web in non-technical prose backed up with scientific research results and related literature. Grant recalls in his article how Wohlleben talked about trees forming alliances among themselves and with other species [1]:

“Some are calling it the ‘wood-wide web,’ ” says Wohlleben in German-accented English. “All the trees here, and in  every forest that is not too damaged, are connected to each other through underground fungal networks. Trees share water and nutrients through the networks, and also use them to communicate. They send distress signals about drought and disease, for example, or insect attacks, and other trees alter their behavior when they receive these messages.”

Other great writings that explain the world-wide web—plus examples of involved species—can be found in journals and blog posts [2-5].

What is the main difference between the wood-wide web and the world-wide web?
The latter is man-made, while, what is called the wood-wide web, is a complex biological system understood as a result of natural selection. World-wide webs—yes, we need to use the plural form since we don't talk about a global structure but locally confined worlds—may be around since the first time when trees and forests began struggling or thriving on earth's landscape.
Keywords: forest ecology, plant science, terminology, communication, signaling, networking.

Forest around Tahoe Meadows above Lake Tahoe: How connected is it?


References and more to explore

[1] Richard Grant: The Whispering of the Trees. Smithsonian, March 2018, 48 (10), pp. 48-57.
[2] Robert Macfarlane: The Secrets of the Wood Wide Web. The New Yorker, August 7, 2016. Link:
[3] Emily Stone: The Wood Wide Web. Featured by William Graham. Link:
[4] How Plants Work: The Wood-Wide-Web: Are Plants Inter-Connected by a Subterranean Fungal Network? Link:
[5] Z. T. Evans: Introduction ot the Wood-wide Web. Tellurian Studies, December 2, 2015. Link: