The Coke and Mentos Experiment


This 3 minutes movie was released about two weeks ago. It displays The Extreme Diet Coke & Mentos Experiment #137. Incredible and funny, is it not? I read somewhere that Mentos company hired both guys for their next advertising campaign.

Since we are in a serious place here, it was but underhand lead-in for a lesson of physics and chemistry: how can little Mentos have such a tremendous effect on a peaceful bottles of Diet Coke? Everyone will agree on the premises: the carbon dioxide (CO2) compressed into the soda escapes so rapidly that the pressure pushes it out of the bottle. It's like shaking a bottle before you open it, but even more dramatic.

Several people theorized that a substance called gum arabic in the Mentos breaks the surface tension of the soda, allowing the CO2 bubbles to escape rapidly. This explanation doesn't completely work though, since several items that contain no gum arabic also cause soda to foam violently.

The primary cause appears to be physical, not chemical: when a liquid is supersaturated with gas, like soda is with CO2, gas is able to form bubbles on nucleation sites (that are places with high surface area in a very small volume, such as scratches on a surface or specks of dust).

Mentos seem to be loaded with nucleation sites: there are so many microscopic nooks and crannies on their surface that an incredible number of bubbles will form when you drop one in a bottle of soda. Since the Mentos are also heavy enough to sink, they react with the soda all the way to the bottom. The escaping bubbles quickly turn into a raging foam, and the pressure builds dramatically.

This mechanism is somewhat similar to the way people whose urine is supersaturated with uric acid or calcium crystals often develop kidney stones. Fortunately enough, crystals are not gas, which probably explains why people with kidney stones usually don't explode.

When I'm Sixty-Four

Sargent Pepper's
The Beatles — Sgt Pepper's  Lonely Hearts Club Band

When I'm sixty four was written by Paul McCartney, who sings it on Beatles' album Sgt. Pepper's Lonely Hearts Club Band, released 1967.

Paul McCartney turns 64 today.

When I get older losing my hair,
Many years from now.
Will you still be sending me a valentine
Birthday greetings bottle of wine?

If I'd been out till quarter to three
Would you lock the door?
Will you still need me, will you still feed me,
When I'm sixty-four?

You'll be older too,
And if you say the word,
I could stay with you.

I could be handy, mending a fuse
When your lights have gone.
You can knit a sweater by the fireside
Sunday mornings go for a ride,

Doing the garden, digging the weeds,
Who could ask for more.
Will you still need me, will you still feed me,
When I'm sixty-four?

Every summer we can rent a cottage,
In the Isle of Wight, if it's not too dear
We shall scrimp and save
Grandchildren on your knee
Vera ,Chuck & Dave.

Send me a postcard, drop me a line,
Stating point of view
Indicate precisely what you mean to say
Yours sincerely, wasting away

Give me your answer, fill in a form
Mine for evermore
Will you still need me, will you still feed me,
When I'm sixty-four?

Pregnant women should not take ACE Inhibitors

Normal ultrasound - 18 weeks pregnancy
Normal ultrasound - 18 weeks pregnancy

For the first time today, I felt it necessary to post something related to my work rather than my hobbies. The issue is worth to be told about indeed, for the information of the ten thousand people who read the present blog every day, ha-ha.

In a group of 209 babies born to women taking Angiotensin-Converting Enzyme inhibitor drugs (ACE inhibitors) in the early stages of pregnancy, a recent study reported that 18 or 7.1% of the infants were born with serious birth defects.

ACE inhibitors are a class of drugs used to treat high blood pressure. They work mainly by relaxing blood vessels and they are often prescribed to people with diabetes. ACE inhibitors include benazepril, captopril, enalapril, fosinopril, lisinopril, moexipril, quinapril, ramipril and trandolapril (these are international names, brand names mostly differ among countries).

Use of ACE inhibitors is contraindicated during the second and third trimesters of pregnancy because of their association with increased risk of fetopathy and renal side effects in the newborn. In contrast, they are not contraindicated in the first trimester of pregnancy — albeit animal reproduction studies have shown an adverse effect on the fetus — because there are no adequate and well-controlled studies in humans and potential benefits may warrant use of the drug in pregnant women despite potential risks, as indicated in drug information sheets (in Europe and USA at least).

The recent study determined that infants exposed to ACE inhibitors in first trimester were about 4 times more likely to suffer cardiovascular problems and 5 times more likely to have central nervous system malformations when compared to infants exposed to other medications or no antihypertensive drugs at all. One-third of the birth defects involved the heart, one-quarter the limbs or the face, and one-tenth involved the brain or spinal cord. Some defects, such as the heart problems, might be curable with surgery or other treatment, but others resulted in retardation or permanent disability.

As highlighted in an accompanying editorial, this study demonstrated the risks of taking known and unknown drugs before and during pregnancy. Women who are considering getting pregnant should talk to their doctor before taking any medications, since "birth defects caused by teratogenic treatments are preventable" the editorial said. "A woman who learns she is pregnant while taking an ACE inhibitor should immediately be switched to another antihypertensive agent to minimize the risk of fetopathy [...]. Detailed fetal ultrasonography and echocardiography at about 18 weeks of gestation should be offered to women who have taken such drugs in the first trimester of pregnancy."

Indeed. And also, one cannot but wonder: "what did pharmaceutical companies selling ACE inhibitors already know but did not say?"

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Timeless Music
The Magic Flute
by W. A. Mozart

Timeless Reading
Les Essais
by Michel de Montaigne