« Older Entries

Nutella: good or bad?

Screen Shot 2017-01-18 at 2.29.36 PM

Turning White Wine into Red

Screen Shot 2017-01-11 at 11.48.07 AM

What takes place in our liver?

Screen Shot 2017-01-11 at 11.31.29 AM

Anesthesia

In 1853 the Queen’s personal physician, Dr. John Snow dripped an ounce of chloroform on a handkerchief which was then held next to the royal mouth as Prince Leopold was delivered.  Her Majesty was very happy with the experience and endorsed the use of chloroform.  Many women followed suit, sometimes even naming their newborn children “Anesthesia.”

YOU ASKED: Why do we refrigerate our eggs?

Screen Shot 2017-01-09 at 3.00.23 PM

You Asked: What are “oxo-biodegradable plastic” shopping bags?

question markPolyethylene shopping bags are a big convenience but they also present a big problem. While they can be recycled, many just get carelessly discarded and end up in the environment not only as an eyesore but as a danger to wildlife. Estimates are that only about 3% of plastics that can be recycled actually are. Polyethylene does not degrade easily in the environment and the bags can end up as pollutants for decades. Some clever chemistry can, however, help the situation.

If certain salts of iron, manganese, nickel or cobalt are incorporated into the polyethylene, polypropylene or polystyrenene molecular chains during manufacture, they will catalyze the breakdown of the polymers. But the breakdown requires the presence of oxygen because the mechanism of the degradation involves “oxidation,” which means forming bonds between some of the carbon atoms in the polymer and oxygen atoms supplied by oxygen in the atmosphere. Exposure to ultraviolet light speeds up the reaction

Once the chain has been “oxidized,” the bonds between the oxygen bearing carbons and their neighbours are significantly weakened and begin to break apart. The resulting short chains are then biodegraded by microbes basically to carbon dioxide and water. Depending on the extent of UV and oxygen exposure, and ambient temperature, oxo-biodegradable plastics visually disappear in as little as two months, although the process can take up to a year and a half. These bags will not degrade in a landfill and therefore will not generate methane, a potent greenhouse gas. They cannot be composted, but they can be recycled just like other polyethylene bags. The big advantage is a reduction in all those bags that end up fluttering from trees or floating in the ocean. Of course, until the plastic breaks down, it can still pose a risk to wildlife but there is no doubt that the oxo-biodegradable plastic is preferable to the conventional variety in terms of impact on the environment.

Read more

Linus Pauling: One of Dr. Joe’s Heroes

Click the image below to watch the video!

Screen Shot 2016-12-22 at 11.06.02 AM

 

Extracting the Goods

Screen Shot 2016-12-16 at 11.23.18 AM

« Older Entries
Blog authors are solely responsible for the content of the blogs listed in the directory. Neither the content of these blogs, nor the links to other web sites, are screened, approved, reviewed or endorsed by McGill University. The text and other material on these blogs are the opinion of the specific author and are not statements of advice, opinion, or information of McGill.