Diurnal and Nocturnal; Log-Blog #07; Sunday, September 16, 2007
(the journal saga of Word Info continues)
A few words from the September 8, 2007, copy of the New Scientist
A rational reason for negative attitudes about dissecting in science classes by children
Why so few schoolchildren do not choose to study science may be explained in a written discussion by Roger Lock in a recent issue of The Biologist, (volume 54, page 59) on the educational importance of children dissecting animals and plants.
Lock suggested that this could involve ethical problems for children of certain religions. "Some schools," he said, "address this issue by asking students to provide their own hearts or kidneys."
Care about "bottoms up"!
On the underside of the boxes of copier paper that arrived at Dyane Silvester's office were the words: "This is the bottom of the box. If you are reading this, the box is upside down, or you need a hobby."
Further, on the wrapper of each ream of paper, there was a note boasting of the high quality of the paper that concludes: ". . . but be aware, it's no substitute for boring or irrelevant content. Please ensure you check this before you press print."
Silvester wonders if the paper-manufacturing company employs someone to make up text like this for its packaging; or has management not yet noticed what's going on?
A new word (for me, at least) is now in existence: oxo-degradable plastic
As I was opening the wrapper of my September 8 issue of New Scientist, I noticed the message printed on the plastic covering: "This polythene is oxo-degradable" with another message saying "recycle" Followed by the words: "When you have finished with this magazine please recycle it."
Of course a search on Google resulted in many sources of information about "oxo-degradable" and "oxo-biodegradable" plastics; so, I will share part of one commercial article which seems to sufficiently summarize what the subject is about.
There are many different types of oxo-biodegradable plastics
When considering packaging and bags, the most important distinction needs to be made between hydro-biodegradable plastics and oxo-biodegradable plastics.
Oxo-biodegradable plastics (also referred to as oxo-degradable plastics) are normal petrochemical based polymers which have a small amount of prodegradant added during the production of the plastic.
The prodegradants act as a catalyst to speed up the degradation process of the plastic and is normally a transition metal.
Some of these metals are considered trace elements and are essential for life; such as, cobalt which is essential for the formation of vitamin B12.
These bags retain all of the advantages of normal plastic bags; however, they provide effective solutions to the compost and landfill industries with minimal disruption of consumer behavioral patterns.
With continued oxidation and reduction in polymer length, the molecular weight of the plastic is reduced to below 40,000, at which point the molecules can be attacked and processed by the enzymic activities of fungi and bacteria. This results in the complete biodegradation of the plastic.
The rate at which this entire process is completed varies with the design of the plastic i.e. which type of polymer is used, the addition rate of the prodegradants, and the type of active ingredient in the prodegradants.
An additional important variable consists of external energy be applied to the plastic; for example, if plastic is littered and thereby receives direct ultra violet light, the disintegration process is hastened, causing the film to break down within weeks. Thereafter biodegradation occurs.
In an industrial compost environment operating at approximately 60°C, the generated heat will ensure disintegration will be complete within the normal compost processing time of 12 weeks, followed by biodegradation and bio assimilation when mixed into soil.
The rate of the biodegradation stage will depend on the type of environment the disintegrated particles end up in.
If placed in soil, the relatively large molecules of polymer are only assimilated by certain microbes. These are the same organisms which assimilate lignin (which is comprised of large naturally occurring polymer molecules).
Lignin makes up the majority of the humus content of compost, thus the rate of degradation depends on the availability of those microbes and it can take four to five years for the carbon in the polymer to be completely absorbed back into the environment.
Because of this slow absorption rate much of the carbon in the plastic is converted into biomass with only a portion being converted to carbon dioxide.
Oxo-biodegradable bags can be used for numerous products and applications because they retain all of the properties of existing plastic such as strength, clarity, water resistance and low cost
Index of journal, or log-blog entries, regarding the Word Info site activities.
Although today's journal did not include anything about entries into the Word Info site, I wanted to include the info in the journal for its humor and the introduction to a word which is apparently being applied more and more often to the "green" tendencies by some companies.