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04.09.2017

what is sarin?

Sarin. The deadly gas.

As you’ve probably heard by now, sarin nerve agent was probably behind the death of more than 80 people in Syria last week. Bashar al-Assad is suspected of using the gas against civilians last week, in what is surely one of the most heinous acts of the ongoing Syrian Civil War. News media showed images of the victims struggling to breathe moving President Donald Trump to engage in a missle strike on Thursday night. The name sarin is an acronym of the four scientists who created it: Gerhard Schrader, Otto Ambros, Gerhard Ritter, and Hans-Jürgen von der Linde.

But what is sarin, and why is it so deadly?

Sarin is a clear colorless gas, that is also known as GB. In it’s purest form it has not taste and no odor. The organophosphorus compound is manufactured by humans, and not found in nature. It was first manufactured in the 1930s.

Sarin is deadly becuse it attacks the nervous system preventing proper degradation acetylcholine at neuromuscular junctions. The nerve gas binds to acetylcholinesterase, an enzyme that degrades the acetylcholine, to send signals between nerves and muscles. This means that when someone is exposed to sarin, even at very low levels, their nerve signals don’t communicate properly with muscles. The muscles do not contract or expand as they usually would. Death after sarin exposure will usually occur as a result suffocation due to the inability to control the muscles involved in breathing. Death usually occurs within 1 to 10 minutes after exposure.

Is there a cure?

There is an antidote for sarin exposure. Atropine treats the physiological symptoms of poisoning, but does not reverse the muscular symptoms. Biperiden is sometimes used as an alternative to atropine due to its better blood–brain barrier penetration and higher efficacy. The drug pralidoxime can regenerate cholinesterase activity, but only if administered within a 5 hour window.

09.21.2016

the science of terror

A string of bombs detonated over the weekend in New York City and New Jersey. The police have arrested Ahmad Khan Rahami in connection with the attacks. C&EN explores the attacks from a scientific angle, looking at the likelihood that two materials – one called Tannerite and another named hexamethylene triperoxide diamine, or HMTD – were used as explosives. On Tannerite:

“It is impossible,” says Daniel Tanner, CEO of Tannerite Sports. Only a high-velocity bullet travelling at a minimum of 610 meters per second can trigger their exploding targets to go off. Tannerite is also resistant to fire, friction, and hard impacts. It cannot be merely jolted into exploding, suggesting that normal bomb triggers wouldn’t set it off. Furthermore, Tanner says finding aluminum or ammonium nitrate residue isn’t enough to say Tannerite was used. “Tannerite is not a compound,” he says. “It is a trademark.”

“Tannerite is not going to go off by itself,” Oxley says. “It is very stable stuff.

And on HMTD:

“HMTD is not stable and not nice stuff. You can easily set it off,” Oxley says. “To use HMTD there has to be some synthesis involved,” she says. Thus far, there are no reports as to how Rahami could have made or obtained HMTD for use in the bombs.

04.10.2016

yvette fay francis-mcbarnette

The New York Times ran an obituary commemorating the life of Dr. Yvette Francis-McBarnette. I had never heard of her but found her life story inspirational, especially for budding minority scientists.

Dr Yvette Fay Francis-McBarnette

Yvette immigrated to New York City from Jamaica with her parents and at 14 years old she began studies at Hunter College. After completing a bachelor’s degree in physics, she began a master’s degree in chemistry at Columbia University. Then she went on to be come only the second black woman to earn a medical degree from Yale University.

As a physician, she made tremendous progress in studying and treating sickle cell anemia in young patients. Sickle cell disease deforms the shape of red blood cells, making them rigid and harder to pass through capillaries. It can lead to oxygen deprivation in organs and tissues and also severe pain. The disease is more prevalent in black and Mediterranean populations.Yvette pioneered new antibiotic treatments for the disease and established the Foundation for Research and Education in Sickle Cell Disease. And she did all of this work during the 1950s and 60s when women had fewer opportunities and less support than exists today, doubly so for black women.