Forwarded from edu.shimichi
🎧 So this is it, with Kit Chapman as our guide through the superheavies, we’ve scaled the highest peak of the periodic table, landing on the enormous element 118, oganesson.
Shimichi
Shimichi.ir – Oganesson: Chemistry in its element
So this is it, with Kit Chapman as our guide through the superheavies, we’ve scaled the highest peak of the periodic table, landing on the enormous element 118, oganesson.
Yuri Oganessian
I’m Yuri Oganessian. I’m a physicist, and in this laboratory I’m the scientific director – I’m responsible for the scientific programme of the laboratory. We have three different programmes of research, one of them is heavy element research. My own interest is heavy and superheavy element research, and I’ve been doing that practically all my life!
First of all, after university, when I come in the lab, I came to the group of professor Flerov, so the interests of the group were not defined by me but by Flerov, who was head of the group. But when we started to do that, it is not only just the properties of the element. It is also nuclear reaction, nuclear interaction, type of decay, nuclear fission, alpha emission and so on and so on. Actually the wide field of nuclear physics – and chemistry of course! It looks, for me, very interesting and I continued that, I didn’t change the area of the research. I am still interested.
Kit Chapman
That’s the voice of a scientist whose name will be remembered forever. Since he joined Flerov’s team at the Joint Institute for Nuclear Research in 1958, Yuri Oganessian, a Russian-born scientist of Armenian descent, has been one of the field leaders when it comes to element discovery. In the 1970s, he was the first to try the cold fusion technique that would lead to the discovery of elements 107 to 113. In the 1990s, it was his hot fusion that expanded the periodic table to complete its seventh row.
But the element that bears his name, element 118, oganesson, almost went to someone else. In 1999, a team at Lawrence Berkeley National Laboratory claimed to have made oganesson by firing krypton into lead. When other teams failed to replicate the results, the claim came under scrutiny. It didn’t take long to find out what happened. In 2002, the claim was retracted by all but one of the authors: Victor Ninov. The lab found that Ninov had fabricated results; re-examination of his earlier work, at GSI in Darmstadt, Germany, showed that original data had been altered there, too. The Ninov scandal rocked element discovery – but the world wouldn’t have to wait long for the real element 118 to emerge.
element 117, fate struck. Berkelium has a very short half-life, and some had decayed into californium. To their surprize, the team made element 118, its half-life of under 0.2 seconds causing it to decay into livermorium, then flerovium, and finally copernicium. It was the smoking gun the team needed to prove the element had been created.
The naming of the element in his honour, decided by his friends and co-workers, has skyrocketed Yuri Oganessian to the world stage. In 2017, Armenia recognised him with stamps in his honour. They all bear the oganesson to coperncium discovery chain that confirmed the last element in the seventh row of the periodic table.
But what does Oganessian himself make of all of the attention?
Yuri Oganessian
Phew… it is difficult to say because it’s a proposal from my collaborators, you know? We work in collaboration with American colleagues – [Lawrence] Livermore National Laboratory, Oak Ridge National Laboratory, Vanderbilt university, Knoxville university, Texas A&M university – all these people were involved in this. They came to this conclusion after all six elements which we synthesised, to give to me. Of course, I mean, it is a great honour for me, if my friends, my colleagues want to express this opinion. I’m still not in a suitable position, in suitable form to say more than that to say more than that! I’m just looking and there’s a lot of things to do! It’s not the final stop, the finish of the story. We may have to go far.
Yuri Oganessian
I’m Yuri Oganessian. I’m a physicist, and in this laboratory I’m the scientific director – I’m responsible for the scientific programme of the laboratory. We have three different programmes of research, one of them is heavy element research. My own interest is heavy and superheavy element research, and I’ve been doing that practically all my life!
First of all, after university, when I come in the lab, I came to the group of professor Flerov, so the interests of the group were not defined by me but by Flerov, who was head of the group. But when we started to do that, it is not only just the properties of the element. It is also nuclear reaction, nuclear interaction, type of decay, nuclear fission, alpha emission and so on and so on. Actually the wide field of nuclear physics – and chemistry of course! It looks, for me, very interesting and I continued that, I didn’t change the area of the research. I am still interested.
Kit Chapman
That’s the voice of a scientist whose name will be remembered forever. Since he joined Flerov’s team at the Joint Institute for Nuclear Research in 1958, Yuri Oganessian, a Russian-born scientist of Armenian descent, has been one of the field leaders when it comes to element discovery. In the 1970s, he was the first to try the cold fusion technique that would lead to the discovery of elements 107 to 113. In the 1990s, it was his hot fusion that expanded the periodic table to complete its seventh row.
But the element that bears his name, element 118, oganesson, almost went to someone else. In 1999, a team at Lawrence Berkeley National Laboratory claimed to have made oganesson by firing krypton into lead. When other teams failed to replicate the results, the claim came under scrutiny. It didn’t take long to find out what happened. In 2002, the claim was retracted by all but one of the authors: Victor Ninov. The lab found that Ninov had fabricated results; re-examination of his earlier work, at GSI in Darmstadt, Germany, showed that original data had been altered there, too. The Ninov scandal rocked element discovery – but the world wouldn’t have to wait long for the real element 118 to emerge.
element 117, fate struck. Berkelium has a very short half-life, and some had decayed into californium. To their surprize, the team made element 118, its half-life of under 0.2 seconds causing it to decay into livermorium, then flerovium, and finally copernicium. It was the smoking gun the team needed to prove the element had been created.
The naming of the element in his honour, decided by his friends and co-workers, has skyrocketed Yuri Oganessian to the world stage. In 2017, Armenia recognised him with stamps in his honour. They all bear the oganesson to coperncium discovery chain that confirmed the last element in the seventh row of the periodic table.
But what does Oganessian himself make of all of the attention?
Yuri Oganessian
Phew… it is difficult to say because it’s a proposal from my collaborators, you know? We work in collaboration with American colleagues – [Lawrence] Livermore National Laboratory, Oak Ridge National Laboratory, Vanderbilt university, Knoxville university, Texas A&M university – all these people were involved in this. They came to this conclusion after all six elements which we synthesised, to give to me. Of course, I mean, it is a great honour for me, if my friends, my colleagues want to express this opinion. I’m still not in a suitable position, in suitable form to say more than that to say more than that! I’m just looking and there’s a lot of things to do! It’s not the final stop, the finish of the story. We may have to go far.
Three models to predict the tendency of a water to form CaCO3 scale:
• The Langelier-Saturation Index (LSI)
• The Ryzner Stability Index (RSI)
• The Puckorius Scaling Index (PSI)
Shimichi.ir
• The Langelier-Saturation Index (LSI)
• The Ryzner Stability Index (RSI)
• The Puckorius Scaling Index (PSI)
Shimichi.ir
LSI = pH - pHs
where pH is the actual pH, and pHs is the pH at saturation. pHs is indicating the other parameters.
Shimichi.ir
where pH is the actual pH, and pHs is the pH at saturation. pHs is indicating the other parameters.
Shimichi.ir
🎧 This week, Kat Arney investigates the biological pigment that links sun tans, squid ink and browning bananas.
Shimichi
Shimichi.ir – Melanin: Chemistry in its element
🎧 This week, Kat Arney investigates the biological pigment that links sun tans, squid ink and browning bananas.
Kat Arney
Beauty may only be skin deep, as the old cliché goes, but melanin – a biological compound mainly known for its role in skin colour – is responsible for much more than just a sun tan. The name comes from the ancient Greek word melanos, meaning dark, and is thought to have first been coined by the Swedish chemist Jacob Berzelius, one of the founding fathers of modern chemistry.
While the word ‘melanin’ is now generally used to refer to dark pigments found in mammals, there are many different types of melanin. It’s the most common pigment in the animal kingdom, but plants, bacteria and fungi also contain versions of melanin – in fact, the brown colour of over-ripe bananas is due to melanin produced by oxidation in the skin.
Whatever the source, melanin is a polymer made up from long chains of modified amino acids and usually packed into tiny granules. (As an aside, polymer is another word first used by Berzelius, although in a different context to the way we use it today, and he’s also credited with inventing the word protein).
ach are controlled by a number of different genetic variations. Dark skin and hair are rich in eumelanin, but pale skin and blond hair have only a smattering while albino people lack melanin altogether. Adding a dash of phaeomelanin into the mix results in strawberry blonde hair, and a big dose is responsible for fiery red.
Phaeomelanin is also responsible for the darker pink skin colouration of certain body parts, such as lips, nipples and genitals, while eumelanin is to blame for moles and freckles. And as sun-seekers everywhere will know, exposure to ultraviolet rays from the sun or a tanning bed leads to a boost in melanin production in the skin and that resulting suntan. It was thought for many years that the sole function of melanin in the skin was as an inbuilt biological sun-screen, which explains why people living in less sunny latitudes have paler skin, but researchers now think that is an overly simplistic explanation.
Because tyrosine is an aromatic amino acid, meaning that it contains a ring of six carbonatoms, the resulting polymer is particularly rich in carbon rings. This creates a structure that’s very good at absorbing a range of light wavelengths from visible to ultraviolet, explaining its dark colour and UV protective properties. But these kinds of chemicals are also very good at mopping up damaging free radicals and toxic molecules, so scientists now think that melanin plays a more general role in maintaining the health of the skin.
To make matters more complicated, melanin isn’t only found in skin and hair. Melanin in the iris determines eye colour, in conjunction with the levels of other molecules. Lots of melanin leads to dark brown eyes, lower levels result in hazel or green, while blue eyes are due to having little melanin. It’s also found in the retina where it helps to cut down on rogue light scattering inside the eyeball, much like painting the inside of a camera black.
Melanin also turns up in the brain in an unusual form known as neuromelanin, located in a region known as the substantia nigra, literally translated as ‘dark matter’. The neurodegenerative condition Parkinson’s disease is caused by the gradual death of brain cells in this area, and some researchers have suggested that a loss of neuromelanin – along with its protective effects – might be linked to the condition. The pigment is also found in the inner ear, although exactly what it’s doing there is still a bit of a mystery.
Other species have come up with alternative uses for melanin. It gives colour to animal fur, bird feathers and butterfly wings. The iridescent sheen seen on the shells of insects such as beetles is due to carefully constructed, highly refractive layers of melanin pigments. Melanins play a role in determining the infectiousness of certain moulds, and protect microorganisms from UV light and chemical damage.
Dipping into the sea, one important natural source o
Kat Arney
Beauty may only be skin deep, as the old cliché goes, but melanin – a biological compound mainly known for its role in skin colour – is responsible for much more than just a sun tan. The name comes from the ancient Greek word melanos, meaning dark, and is thought to have first been coined by the Swedish chemist Jacob Berzelius, one of the founding fathers of modern chemistry.
While the word ‘melanin’ is now generally used to refer to dark pigments found in mammals, there are many different types of melanin. It’s the most common pigment in the animal kingdom, but plants, bacteria and fungi also contain versions of melanin – in fact, the brown colour of over-ripe bananas is due to melanin produced by oxidation in the skin.
Whatever the source, melanin is a polymer made up from long chains of modified amino acids and usually packed into tiny granules. (As an aside, polymer is another word first used by Berzelius, although in a different context to the way we use it today, and he’s also credited with inventing the word protein).
ach are controlled by a number of different genetic variations. Dark skin and hair are rich in eumelanin, but pale skin and blond hair have only a smattering while albino people lack melanin altogether. Adding a dash of phaeomelanin into the mix results in strawberry blonde hair, and a big dose is responsible for fiery red.
Phaeomelanin is also responsible for the darker pink skin colouration of certain body parts, such as lips, nipples and genitals, while eumelanin is to blame for moles and freckles. And as sun-seekers everywhere will know, exposure to ultraviolet rays from the sun or a tanning bed leads to a boost in melanin production in the skin and that resulting suntan. It was thought for many years that the sole function of melanin in the skin was as an inbuilt biological sun-screen, which explains why people living in less sunny latitudes have paler skin, but researchers now think that is an overly simplistic explanation.
Because tyrosine is an aromatic amino acid, meaning that it contains a ring of six carbonatoms, the resulting polymer is particularly rich in carbon rings. This creates a structure that’s very good at absorbing a range of light wavelengths from visible to ultraviolet, explaining its dark colour and UV protective properties. But these kinds of chemicals are also very good at mopping up damaging free radicals and toxic molecules, so scientists now think that melanin plays a more general role in maintaining the health of the skin.
To make matters more complicated, melanin isn’t only found in skin and hair. Melanin in the iris determines eye colour, in conjunction with the levels of other molecules. Lots of melanin leads to dark brown eyes, lower levels result in hazel or green, while blue eyes are due to having little melanin. It’s also found in the retina where it helps to cut down on rogue light scattering inside the eyeball, much like painting the inside of a camera black.
Melanin also turns up in the brain in an unusual form known as neuromelanin, located in a region known as the substantia nigra, literally translated as ‘dark matter’. The neurodegenerative condition Parkinson’s disease is caused by the gradual death of brain cells in this area, and some researchers have suggested that a loss of neuromelanin – along with its protective effects – might be linked to the condition. The pigment is also found in the inner ear, although exactly what it’s doing there is still a bit of a mystery.
Other species have come up with alternative uses for melanin. It gives colour to animal fur, bird feathers and butterfly wings. The iridescent sheen seen on the shells of insects such as beetles is due to carefully constructed, highly refractive layers of melanin pigments. Melanins play a role in determining the infectiousness of certain moulds, and protect microorganisms from UV light and chemical damage.
Dipping into the sea, one important natural source o
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و نمک های آن به عنوان یک ترکیب بیس فسفونات از جمله مهمترین متیلن فسفونات های مورد استفاده در شوینده ها و محصولات بهبهود دهنده آب می باشد.
www.shimichi.com
@shimichi
و نمک های آن به عنوان یک ترکیب بیس فسفونات از جمله مهمترین متیلن فسفونات های مورد استفاده در شوینده ها و محصولات بهبهود دهنده آب می باشد.
www.shimichi.com
@shimichi
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