Liberal Arts Blog — Selenium (Se) — Trace Amounts Key To Cellular Function; Industrial Sources And Uses; Photovoltaic And Photoconductive Effect
Liberal Arts Blog — Wednesday is the Joy of Science, Engineering, and Technology Day
Today’s Topic — Selenium (Se) — trace amounts key to cellular function; industrial sources and uses; photovoltaic and photoconductive effect
Selenium is essential to human reproduction and the metabolism of thyroid hormones.
Its industrial uses include glass making and photocells. It was discovered by the Swedish chemist Jacob Berzelius in 1817, but it was not until 1975 that an American scientist figured out the vital role in plays in the human body. “The metallic form of selenium has the curious property of conducting electricity a thousand times better when light falls on its surface and so it is used in photoelectric cells, light meter, solar cells and photocopiers.”
Every day is a great day to marvel at the mysteries of the Periodic Table! The intricacies of each and how they combine with others to make things like us, non-stick frying pans, and ozone-destroying chlorofluorocarbons!
This is the 27th in a series on the marvels and mysteries of the Periodic Table.
We began with phosphorus, then nitrogen, potassium, sodium, calcium, oxygen, hydrogen, chlorine, carbon, copper, iron, and lead. Then we proceeded to silicon, zinc, magnesium, gold, platinum. Then a break to discuss the eclipse. Then a return with molybdenum, helium, Iodine, manganese, lithium, fluorine, and most recently, titanium.
What do you know about selenium that the rest of us might delight to learn?
Experts — please chime in. Correct, elaborate, elucidate.
“EVERY CELL IN THE BODY CONTAINS MORE THAN A MILLION ATOMS OF SELENIUM”
1. Areas of highest concentration: thyroid, hair, kidneys, testicles.
2. “The recommended maximum daily intake is 450 micrograms.”
3. “Above this we risk selenium poisoning, the most obvious symptoms of which are extremely foul breath and body odor, sometimes experienced by those working with selenium in industry.”
NB: used as an ingredient in multivitamins and infant formula.
“IN 1975 SELENIUM WAS PROVED TO BE AN ESSENTIAL ELEMENT FOR HUMANS”
1. “Yogesah Awasthi, based in Galveston in Texas, discovered that it was part of the antioxidant enzyme, gultathione peroxidase, which eliminates peroxides before they can become dangerous free-radicals.”
2. ‘Then in 1991, Professor Dietrich Behne at the Hagn-Meitner Institute in Berlin found selenium in another enzyme, deiodinase, which promotes hormone production in the thyroid gland.”
3. “Most people get their daily dose of selenium from breakfast cereals and bread.” Other sources; fish (tuna, cod, salmon), offal (liver, kidney), nuts (Brazil nuts, peanuts).
FROM METALLURGY AND GLASS TO PHOTOCELLS, SOLAR CELLS, AND PHOTOCOPIERS
1. The principal source of selenium: “the slime that settles at the bottom of tanks when copper is refined electrolytically, this slime may contain up to 5% selenium” (Emsley)
2. “Selenium is used to make pigments for ceramics, paint, and plastics.”
3. “Selenium has both a photovoltaic (converts light to electricity) and a photoconductive action (electrical resistance decreases with increased illumination). It is therefore useful in photocells, solar cells, and photocopiers. It can also convert AC electricity to DC electricity so is extensively used in rectifiers.”
NB: “Selenium is toxic to scalp fungus that causes dandruff so it is used in some anti-dandruff shampoos. Selenium is also used as an additive to make stainless steel.”
ETYMOLOGY (the Greek moon goddess) AND DISCOVERY (Berzelius, 1817. below)
1. Selenium is named after Selene, the Greek goddess of the Moon (sister of the sun God, Helios, and the dawn goddess, Eos.)
2. It was discovered by the great Swedish chemist Jons Jacob Berzelius (1779–1848) considered to be along with Robert Boyle, John Dalton, and Antoine Lavoisier, to be “one of the founders of modern chemistry.”
Jöns Jacob Berzelius — Wikipedia
Selenium — Element information, properties and uses | Periodic Table
John Emsley, Nature’s Building Blocks: An A-Z Guide to the elements — highly recommended.
Definitely my favorite chemistry book of all time.
QUOTE OF THE MONTH
“Make your own Bible. Select and collect all the words and sentences that in all your readings have been to you like the blast of a trumpet.”
- Ralph Waldo Emerson
My spin — then periodically review, re-rank, and exchange your list with those you love. I call this the “Orion Exchange” because seven is about as many as any human can digest at a time. Game?
A LINK TO THE LAST FOUR YEARS OF POSTS ORGANIZED BY THEME:
PDF with headlines — Google Drive
ATTACHMENT BELOW -
#1 A graphic guide to justice (9 metaphors on one page).
#2 “39 Songs, Prayers, and Poems: the Keys to the Hearts of Seven Billion People” — Adams House Senior Common Room Presentation, (11/17/20)
NB: Palestine Orion (Decision) — let’s exchange Orions, let’s find Rumi’s field (“Beyond all ideas of right and wrong, there is a field. Meet me there” Rumi, 13 century Persian Sufi mystic)
YOUR TURN
Please share the coolest thing you learned this week related to science, engineering, or technology.
Or, even better, the coolest or most important thing you learned in your life related to science and engineering.
This is your chance to make someone else’s day. Or to cement in your mind something that you might otherwise forget. Or to think more deeply about something dear to your heart. Continuity is key to depth of thought.
