x ray diffraction

anonymous asked:

Why the strong feels against Watson and crick?

Because of this.

One sentence. Her hard work was STOLEN and they gave her one friggin sentence in the acknowledgement section. Meanwhile they’re riding the cash cow to fame and glory, heralded as these biological geniuses.

It seems like textbooks have become more progressive in the past 5 years or so, but the biology textbook I was issued in high school (published in the early 2000s) dedicated a small, 2-3 sentence paragraph to Rosalind Franklin (which mostly focused on explaining what X-ray crystallography was, not focusing on her contribution or Watson and Crick’s theft of her experimental data), while Watson and Crick received an entire full page spread with their iconic photograph, posing next to a giant DNA model. The most recent version of that textbook now has an entire page dedicated to Rosalind and even includes a picture of her, though!

(Pierce, B. 2012. Genetics: A Conceptual Approach. 4th ed.)

Watson and Crick took credit for Franklin’s work and got away with it because she was a woman. She couldn’t even be awarded the Nobel prize because she died as a result of the radiation from the very X-ray diffraction techniques she used to discover the structure of DNA. Women were not taken seriously in science back then and even still today there is a huge deficit of females in STEM fields.

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February 28th 1953: Watson and Crick discover DNA structure

On this day in 1953, scientists James D. Watson and Francis Crick discovered the chemical structure of DNA. They made the discovery of the double helix structure while building a cardboard model of the molecule in their laboratory at Cambridge University. Their model of DNA was based on an X-ray diffraction image taken by Rosalind Franklin and the fact that DNA bases are paired; due to her gender, Franklin is often forgotten in narratives of scientific history. Watson and Crick first announced their discovery to friends and it was not formally announced to the wider scientific community until April 25th. Watson, Crick and Maurice Wilkins were jointly awarded the 1962 Nobel Prize for Physiology or Medicine for their discoveries. The discovery was a groundbreaking moment for science, and lay the foundations for the research into DNA and the investigation of human genetics.

“We have found the secret of life.”
- Francis Crick

anonymous asked:

what kind of chemistry do you do?

I’m an inorganic synthetic chemist who specializes in a few heavy metals and a specific type of structure using different flexible ligands (I’m afraid I can’t be less vague; my research is specialized enough that it would be rather identifiable).

In general, I design molecules with my metal/ligand components and synthesize (or attempt to synthesize) them in lab. I then work the compounds up through crystallization so I can utilize single crystal x-ray diffraction on an instrument like this:

This bombards the crystal with x-rays and allows me to collect data to produce a structure of the molecule, which gives me bond lengths, angles, etc. This is the crystal I’m currently running (it’s huge and awful, really, but I just need to confirm what it is before I care about a better collection). The crystal looks enormous on the screen - and it is large by my usual standards - but in actuality, the loop the crystals sit on are quite small:

The crystals go on the very tip of that loop, so I do a lot of work under a microscope.

It’s a pretty neat process (when reactions behave), and for the most part I do enjoy my work. Bonus perk is that many of my compounds display luminescence, so I keep a black light handy:

Sea cucumbers can eviscerate themselves as a defense mechanism.

When using a microscope to study particularly small organisms, placing a drop of immersion oil on top of the slide cover will focus the light from the microscope and further magnify the specimen.

Rosalind Franklin died of ovarian cancer six years after using x-ray diffraction to identify the physical structure of DNA. Other people were awarded a Nobel Prize for her discovery; there is a very strict rule that a Nobel Prize cannot be given to someone who is dead. It isn’t like the Oscars. Her cancer was probably caused in part by excessive exposure to radiation.

A sound occuring below the frequency of twenty Hertz–the lowest sound usually detectable by the human ear–is referred to as infransound. Infrasonic noises may cause pain in the eardrum, and/or inexplicable feelings of dread.

When trying to identify which chamber of a human heart you are observing, it is helpful to know that the atria have smooth walls, whereas the ventricles’ are textured, and that the walls of the heart are much thicker on the left side than on the right.

Eels have not been observed spawning in nature.

The oldest confirmed wild bird is approximately sixty-six years old; her name is Wisdom and she has flown more than three million miles.

Human beings can also eviscerate themselves as a defense mechanism, but this is often called an Emotional Disturbance.

Scientists create 'diamond rain' that forms in the interior of icy giant planets

In an experiment designed to mimic the conditions deep inside the icy giant planets of our solar system, scientists were able to observe “diamond rain” for the first time as it formed in high-pressure conditions. Extremely high pressure squeezes hydrogen and carbon found in the interior of these planets to form solid diamonds that sink slowly down further into the interior.

The glittering precipitation has long been hypothesized to arise more than 5,000 miles below the surface of Uranus and Neptune, created from commonly found mixtures of just hydrogen and carbon. The interiors of these planets are similar – both contain solid cores surrounded by a dense slush of different ices. With the icy planets in our solar system, “ice” refers to hydrogen molecules connected to lighter elements, such as carbon, oxygen and/or nitrogen.

Keep reading

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Scientists create ‘diamond rain’ that forms in the interior of icy giant planets

SLAC’s X-ray laser and Matter in Extreme Conditions instrument allow researchers to examine the exotic precipitation in real-time as it materializes in the laboratory

In an experiment designed to mimic the conditions deep inside the icy giant planets of our solar system, scientists were able to observe “diamond rain” for the first time as it formed in high-pressure conditions. Extremely high pressure squeezes hydrogen and carbon found in the interior of these planets to form solid diamonds that sink slowly down further into the interior.

The glittering precipitation has long been hypothesized to arise more than 5,000 miles below the surface of Uranus and Neptune, created from commonly found mixtures of just hydrogen and carbon. The interiors of these planets are similar–both contain solid cores surrounded by a dense slush of different ices. With the icy planets in our solar system, “ice” refers to hydrogen molecules connected to lighter elements, such as carbon, oxygen and/or nitrogen.

Researchers simulated the environment found inside these planets by creating shock waves in plastic with an intense optical laser at the Matter in Extreme Conditions (MEC) instrument at SLAC National Accelerator Laboratory’s X-ray free-electron laser, the Linac Coherent Light Source (LCLS).

In the experiment, they were able to see that nearly every carbon atom of the original plastic was incorporated into small diamond structures up to a few nanometers wide. On Uranus and Neptune, the study authors predict that diamonds would become much larger, maybe millions of carats in weight. Researchers also think it’s possible that over thousands of years, the diamonds slowly sink through the planets’ ice layers and assemble into a thick layer around the core.

The research was published in Nature Astronomy on August 21.

“Previously, researchers could only assume that the diamonds had formed,” said Dominik Kraus, scientist at Helmholtz Zentrum Dresden-Rossendorf and lead author on the publication. “When I saw the results of this latest experiment, it was one of the best moments of my scientific career.”

Earlier experiments that attempted to recreate diamond rain in similar conditions were not able to capture measurements in real time, due to the fact that currently we can create these extreme conditions under which tiny diamonds form only for very brief time in the laboratory. The high-energy optical lasers at MEC combined with LCLS’s X-ray pulses–which last just femtoseconds, or quadrillionths of a second–allowed the scientists to directly measure the chemical reaction.

Other prior experiments also saw hints of carbon forming graphite or diamond at lower pressures than the ones created in this experiment, but with other materials introduced and altering the reactions.

The results presented in this experiment is the first unambiguous observation of high-pressure diamond formation from mixtures and agree with theoretical predictions about the conditions under which such precipitation can form and will provide scientists with better information to describe and classify other worlds.

Turning Plastic Into Diamond

In the experiment, plastic simulates compounds formed from methane–a molecule with just one carbon bound to four hydrogen atoms that causes the distinct blue cast of Neptune.

The team studied a plastic material, polystyrene, that is made from a mixture of hydrogen and carbon, key components of these planets’ overall chemical makeup.

In the intermediate layers of icy giant planets, methane forms hydrocarbon (hydrogen and carbon) chains that were long hypothesized to respond to high pressure and temperature in deeper layers and form the sparkling precipitation.

The researchers used high-powered optical laser to create pairs of shock waves in the plastic with the correct combination of temperature and pressure. The first shock is smaller and slower and overtaken by the stronger second shock. When the shock waves overlap, that’s the moment the pressure peaks and when most of the diamonds form, Kraus said.

During those moments, the team probed the reaction with pulses of X-rays from LCLS that last just 50 femtoseconds. This allowed them to see the small diamonds that form in fractions of a second with a technique called femtosecond X-ray diffraction. The X-ray snapshots provide information about the size of the diamonds and the details of the chemical reaction as it occurs.

“For this experiment, we had LCLS, the brightest X-ray source in the world,” said Siegfried Glenzer, professor of photon science at SLAC and a co-author of the paper. “You need these intense, fast pulses of X-rays to unambiguously see the structure of these diamonds, because they are only formed in the laboratory for such a very short time.”

Nanodiamonds at Work

When astronomers observe exoplanets outside our solar system, they are able to measure two primary traits–the mass, which is measured by the wobble of stars, and radius, observed from the shadow when the planet passes in front of a star. The relationship between the two is used to classify a planet and help determine whether it may be composed of heavier or lighter elements.

“With planets, the relationship between mass and radius can tell scientists quite a bit about the chemistry,” Kraus said. “And the chemistry that happens in the interior can provide additional information about some of the defining features of the planet.”

Information from studies like this one about how elements mix and clump together under pressure in the interior of a given planet can change the way scientists calculate the relationship between mass and radius, allowing scientists to better model and classify individual planets. The falling “diamond rain” also could be an additional source of energy, generating heat while sinking towards the core.

“We can’t go inside the planets and look at them, so these laboratory experiments complement satellite and telescope observations,” Kraus said.

The researchers also plan to apply the same methods to look at other processes that occur in the interiors of planets.

In addition to the insights they give into planetary science, nanodiamonds made on Earth could potentially be harvested for commercial purposes - uses that span medicine, scientific equipment and electronics. Currently, nanodiamonds are commercially produced from explosives; laser production may offer a cleaner and more easily controlled method.

Research that compresses matter, like this study, also helps scientists understand and improve fusion experiments where forms of hydrogen combine to form helium to generate vast amounts of energy. This is the process that fuels the sun and other stars but has yet to be realized in a controlled way for power plants on Earth.

In some fusion experiments, a fuel of two different forms of hydrogen is surrounded by a plastic layer that reaches conditions similar to the interior of planets during a short-lived compression stage. The LCLS experiment on plastic now suggests that chemistry may play an important role in this stage.

“Simulations don’t really capture what we’re observing in this field,” Glenzer said. “Our study and others provide evidence that matter clumping in these types of high-pressure conditions is a force to be reckoned with.”

anonymous asked:

omg thank you so much for putting rosalind franklin in the dna history post!!

And also:

i think it is more correct to say that in 1953 Watson and Crick stole Rosalind’s picture to build their model, and when they published it, of course they didn’t gave her any credit. I think it is important for people to know that Rosalind Franklin discovered the antiparallel structure of the DNA molecule, but since her studies and researches were published after Watson and Crick’s, she didn’t get any recognition until many years later. (Sorry for the long message!)

Hello Nonnies!!

We can’t not talk about Rosalind Franklin. She is an awesome lady that is slowly getting the recognition she deserves in the scientific community.

(We also went to an all girls catholic highschool with large emphasis on science, and her name always came up in all of the science classes. It’s pretty hard to forget her name now. We are also going to hijack these asks to give a more in-depth biography for Rosalind Franklin.)

Franklin was a gifted X-ray crystallographer. She was a research associate at King’s College London in 1951, moved to Birkbeck College in 1953. She died at the early age of 37 due to ovarian cancer. Really she should have gotten the same Nobel Prize that Watson, Crick, and Wilkins shared in 1962 for the discovery of the DNA double helix, but the Nobel Committee are pricks and don’t award prizes posthumously.

Franklin’s the one to first contribute the concept of the two forms of DNA; A-DNA (dried, short and fat), and B-DNA (wet, long and thin). Photo 51 (image from Wikipedia) is the x-ray diffraction pattern developed while at King’s College that leads to the discovery of DNA double helix structure.

There has been some controversies surrounding the nature of her work being used by Watson and Crick. Allegations where made that Photo 51 was shown to Watson by her colleague Wilkins without Franklin’s permission (bad science ethics here) but we are not sure how true that allegation is. Franklin did not gain much recognition for her contribution originally, all that was mentioned was a footnote acknowledging that it was based on “general knowledge” of Franklin’s unpublished contribution.

Rosalind Franklin is a good example of sexism in science. She’s not gaining a lot of posthumous recognition for her work. I would also like to think that she’s an awesome role model for a lot of girls pursuing science as a field of study.

Ok so some of you remember the crystallization stuff from my field study that I posted

Well it turns out today I got to take a much closer look at the crystals I made and shoot them through the X-ray machine.

So here’s one of the tubes with the MANY crystals of hemoglobin (with the drug). I showed you something like that last week.

I got to use the microscope to look at them up close and pick a good enough crystal to shoot through the X-ray diffraction machine. 

LOOK AT HOW FUCKING BEAUTIFUL THEY ARE

So the crystal we picked went under a glycerin/mother liquor solution to protect it from breaking down. (Below: the crystals on the left, the solution on the right, and the original mother liquor is behind the solution) 

Mother liquor is the liquid leftover after a crystallization btw.

So the crystal was picked up with a really tiny “lasso” tool so it could be hooked up onto the X-ray machine.

That tiny, pointy thing has a REALLY small hoop at the tip of it to pick the crystal up.

here’s a pic of it up close; that’s how small the hoop and crystal is

and this is the X-ray diffraction machine. 

The crystal is held up here:

and this “shoots” towards the crystal which lets it’s X-rays scatter and that gives us information on the crystalline structure. That ultimately lets us know about the structure of the individual molecules. 

Here’s an up close look at the crystal that was picked:

That’s after it was mounted on the X-ray machine. It’s hard to see cause it’s in front of the black screen.

and that’s the “X-ray” of the crystal we got. The individual dots are the individual components of the crystal. (We actually diffracted a second crystal to get a better x-ray because the dots were too close together on this one). This basically lets us see each unit cell of the crystal itself which would contain a repeat of the hemoglobin molecule with the drug/compound in this case.

By next week, I’ll be able to take a look at the actual protein structure of the Hb molecule and the drug and see how they bind together.

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you know what really grinds my gears? people excluding Rosalind Franklin from the discovery of the DNA double helix due to HER revolutionary photo in which she used x-ray diffraction, which is super dangerous by the way. don’t deny Rosalind Franklin credit for this crucial scientific discovery!!

7

This car was manufactured in 1965 by the Rolls-Royce Motor Cars Limited, Crewe, Cheshire. The car was fitted with a limousine body by Mulltner Park Ward and finished in Valentines Black.
When completed, the Phantom V was then delivered to John Lennon on June 3, 1965 with the license plate number being FJB111C. A guarantee was issued to John Lennon on 10 June 1965. The car measured 19 feet long and weighed three tons.
On December 21, 1965, John ordered a Sterno Radio Telephone and the number WEYBRIDGE 46676 assigned to it.
In 1966, the car had the rear seat modified to convert to a double bed. A custom interior/exterior sound system was installed along with a “loud hailer.” Other features that John Lennon had installed at this time were: Sony television; telephone and a portable refrigerator. On January 7, the car went in for a mileage check and the odometer had recorded 6,673 miles and on March 28, that same year, the car clocked in at 11,181 miles. Later, on February 4, in 1967, the odometer would record 29,283 miles clocked on the Rolls-Royce. Interestingly enough, John had his chauffeur and car sent over to Spain in 1966, while he was filming “How I Won the War”. It was reported that his Rolls-Royce Phantom V was painted with a matt black overall, which included the radiator and chrome trim.
But John eventually became restless with the “matt black overall” on the car and so in April of 1967, he took it upon himself to visit J.P. Fallon Limited, a coachworks company located in Chertsey, Surrey. He had in mind the possibility of having his car painted “psychedelic”. This was based on an idea by Marijke Koger (“The Fool” who was a member of Dutch team of gypsy artists). After discussing the idea, J.P. Fallon Limited commissioned Steve Weaver’s pattern of scroll and flowers for the Phantom V. The cost for having the work done came in at £2,000 and the car was painted by the original gypsies who made the gypsy wagon that was in Lennon’s garden
John’s newly painted psychedelic car drew some public outrage when a old woman attacked the car using her umbrella and yelling: “You swine, you swine! How dare you do this to a Rolls-Royce.” Obviously, the Rolls-Royce is passionately regarded in England as one of the many symbols of British dignity!
The Beatles used the Rolls exclusively in their heyday from 1966 to 1969.
In 1970, John Lennon and Yoko Ono had the Phantom V shipped to the United States. The car was loaned out to several rock stars such as the Rolling Stones, the Moody Blues, and Bob Dylan. When the car was available, the Lennon’s seldom used it and so consideration was given to sell it to an American buyer – but a deal never materialized. As a result, the car was put into storage in New York City.
Then in December, 1977, John and Yoko had serious problems with the United States Internal Revenue. The couple arranged to have a deal worked out where they would donate the car to the Cooper-Hewitt Museum in New York City, a part of the Smithsonian Institute, for a $225,000 tax credit.
From October 3, 1978 to January 7, 1979, the car was put on public display at the Cooper-Hewitt Museum and then returned to storage at Silver Hill, Maryland. There, the car would remain in storage and kept from public viewing for a while. The reason for this was because the museum could not afford the insurance coverage for public viewing on a full-time basis.
On June 29, 1985, the Cooper-Hewitt Museum decided to auction the car off through Sotheby’s. Before the auction began, The Rolls-Royce Phantom V was estimated by Sotheby’s to fetch between $200,000 to $300,000 (U.S.). When the car was sold, it pulled in a surprising $2,299,000 (U.S.) and was purchased by Mr. Jim Pattison’s Ripley International Inc., of South Carolina for exhibition at Ripley’s “Believe It Or Not” museum. The purchase of the Phantom V through Sotheby’s resulted it being listed as the most expensive car in the world and installed with the South Carolina license plates LENNON.
The Phantom V was then loaned to Expo ‘86 in Vancouver (Chairman: Mr. Jim Pattison) for exhibition. The American title was transferred from Ripley International Inc. to Jim Pattison Industries Ltd., in Canada (Mr. Jim Pattison is a well-known British Columbia business man.)
In 1987, Mr. Pattison presented the car as a gift to Her Majesty in Right of the Province of British Columbia and displayed in the Transportation Museum of British Columbia at Cloverdale (near Vancouver).
Then, in 1993, the car was transferred from the Transportation Museum and sent to the Royal British Columbia Museum in Victoria, British Columbia. Here the car would be kept for secure storage, displayed only for fund-raising and occasional use. The car was serviced and maintained by Bristol Motors of Victoria.
PAINT LONGEVITY ON LENNON’S ROLLS-ROYCE…
In order to protect the paint work on John Lennon’s famous Rolls-Royce Phantom V, the Royal Royal British Columbia Museum requested that the Canadian Conservation Institute (CCI) do a paint analysis on the car. Here are the test results as reported from the CCI:
“Samples were mounted as cross sections to determine the structure of the paint layers. Paint chips were also analysed using Fourier transform infrared spectroscopy, X-ray diffraction, X-ray microanalysis, and polarized light microscopy. The analysis revealed that both cellulose nitrate and an oil-modified alkyd resin media had been used and that the surface of the paint had been coated with an oil-modified alkyd resin varnish. A colourful array of pigments was identified, including chrome yellow, titanium white, ultramarine blue, and toluidine red.
"Based on the materials identified, cleaning and waxing the car was recommended; the analysis showed there was nothing in the paint that would be harmed by water or by the application of a protective wax coating. To minimize damage to the varnish and painted surface, it was also recommended that the car not be exposed to direct sunlight for long periods as this could cause deterioration of both the cellulose nitrate and the alkyd resin.”
However, over the years the car has had some paint cracking on the original top coat. Restoration work was applied.

From 9 March 1996 to 15 September 1996, John Lennon’s Rolls-Royce Phantom V was displayed at the National Museum of Science and Technology in Ottawa, with as passenger a sculpture of John by Joanne Sullivan.
“During the making of Sergeant Pepper John decided to have the Rolls-Royce painted. Colour and design were of the utmost priority and he employed a firm of barge and caravan designers to do it for him. The idea came to him when he bought an old gypsy caravan for the garden.”– Cynthia Lennon, from her book, “A Twist of Lennon”

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Single Crystal X-Ray Diffraction is a highly useful technique for chemists and biologists, because it allows us image molecules with virtually atomic fidelity, and is responsible in part for helping realise the structure of DNA and many important proteins 

X-Ray Diffraction [XR-D] works by firing X-rays at a target (in this case, a very small crystal that has been mounted upon a goniometer - the circular object in the second picture), and observing the scattering pattern the X-rays make as they diffract. By rotating the crystal around and striking it from a variety of locations a huge assembly of diffraction patterns can be collected. These form the basis of an electron density map. Since different atomic nuclei have differently sized electron clouds, an experienced crystallographer can assign atoms to certain spots in the electron density map. If the assignment agrees well with the data then he can build a crystal structure. 

The great thing about crystal structures is that they give chemists and biologists a peek at what the molecule really looks like, in an unambiguous sense. We can determined the geometry of the molecule. the bond angles between atoms and even the strength of those bonds (given by their bond length). For medicinal chemists and biologists, this kind of data (when taken from enzymes, and proteins) can be used to see if molecules fit into receptor sites or the active sites of biologically relevant molecules. A good crystal structure is often essential to producing medicinally relevant studies and compounds. 

Single Crystal XR-D is not infallible or easy to accomplish though. You must first obtain an X-ray quality crystal of your compound. This means you must have a very pure sample, and that it will in fact crystallize well. Often purification is a limiting factor for crystal studies - but very often you will encounter chemicals that are very reluctant to crystalize. Greasy compounds, like those with long hydrocarbon chains or which are found in cell membranes may be hard to crystallize, and extreme methods may be employed. 

This also highlights the other downfall of XR-D studies; the crystal form may not be the “native” conformation. If we crystallize a compound that is usually a liquid environment or is suspended in a cell membrane, then that compound will be in a different geometry than where it would be naturally. This can make assigning interactions even more difficult. 

None-the-less, most chemists and biologists are quite excited to produce high quality crystals, and to get structures from them. XR-D still tells us allot about a molecule. Where its strongest bonds are. Where its best sites of interaction are. How it may align itself with other molecules. That, and it is very gratifying to be able to show a chemical structure to your non-scientist buddies and say “I made this,”. 

Rosalind Franklin (25 July 1920 - 16 April 1958)

Rosalind Franklin is considered a pioneer molecular biologist who greatly contributed to the understanding of the fine molecular structure of DNA, RNA, viruses, coal, and graphite. Specifically, she is best know for her work on the X-ray diffraction images of DNA which led to the discovery of the DNA double helix. Crick and Watson’s 1953 model regarding the structure of DNA would not have been possible without her data. Franklin’s images of X-ray diffraction (shown above), which confirmed the helical structure of DNA, were shown to Watson without her approval or knowledge. For this reason, there is possibly no other female scientist with as much controversy surrounding her work. 

Franklin knew she wanted to be a scientist from an early age (15) and studied at Cambridge and graduated in 1941. After Cambridge, she spent three years in Paris where she learned X-ray diffraction techniques. She then returned to London in 1951 to work in John Randall’s laboratory at King’s College. It was there that Randall gave Franklin responsibility for her DNA project and where she met Wilkins. Wilkins was away when she was first hired on, and apparently when he returned he misunderstood her role and assumed she was a technical assistant, when she was in fact his peer. During her work on the DNA project (1951-1953) she came very close to solving the DNA structure. She was beaten to publication by Crick and Watson, which some believe could be attributed to the friction between Wilkins and herself. Wilkins showed Watson one of Franklin’s photographs of DNA, and apparently when Watson saw the photo the solution came to him. 

James Watson, Francis Crick, and Maurice Wilkins received a Nobel prize in Physiology or Medicine for the double-helix model of DNA in 1962. This was four years following Franklin’s death at age 37 from ovarian cancer. Debate on the amount of credit due to Franklin for the DNA model continues to this day. 

“Science and everyday life cannot and should not be separated." 

Atomic-level view provides new insight into translation of touch into nerve signals

Whether stubbing a toe or stroking a cat, the sensation of touch starts out as a mechanical force that is then transformed into an electrical signal conveying pain or other sensations. Tiny channels in neurons act as translators by helping to formulate that signal to the brain. However, scientists know little about the fine details of how these channels work.

(Image caption: Molecular roadblock: The TRAAK channel (purple and orange) dampens sensations by letting potassium ions escape from a neuron. Researchers found the channel uses a never-before-seen system for blocking that flow of ions when it closes: A lipid (yellow) from the neuron membrane (gray) protrudes into the channel.)

New work at Rockefeller University has revealed that one such channel in humans responds to mechanical force using a never-before-seen mechanism. Researchers led by Roderick MacKinnon, John D. Rockefeller Jr. Professor and head of the Laboratory of Molecular Neurobiology and Biophysics examined the TRAAK channel, which is involved in painful touch sensation, at the molecular and atomic levels, finding that it works by reducing the flow of potassium ions that create an electrical signal. The researchers’ findings were released today (December 3) in Nature.

”It is fascinating to wonder how living cells evolved molecules capable of turning small mechanical forces, such as those associated with touch, into electrical signals in the nervous system. That question served as the impetus for this work,” MacKinnon says.

The channels that act as gates in the membranes that envelop neurons, including TRAAK, allow electrically charged atoms, called ions, to move in or out. It’s this movement that is the basis for an electrical signal that carries information. TRAAK channels are one of 78 types of channels in the human body that transport potassium ions; there are other devoted to other ion types. By allowing potassium to trickle out of the neuron, TRAAK normally quiets the neurons, balancing out other channels, which would otherwise create a strong electrical signal for pain.

“TRAAK acts kind of like the brakes on a painful touch sensation, while other channels act as the gas. If you take away the brakes, innocuous touch becomes painful,” says first author Stephen Brohawn, a postdoc in the lab.

Prior work in the lab has shown TRAAK responds to membrane tension – that is stretching caused by a physical force. However, it wasn’t clear how this force caused the channel to open. In fact, scientists had previously only explained the workings of two mechanical-force sensing channels, both of which are found in bacteria.

After purifying the protein that makes up TRAAK, the team crystallized it and determined its structure using X-ray diffraction analysis. Based on the pattern produced by X-rays bounced off the crystallized protein, scientists can infer the structure of the molecule. But because it is difficult to get high-quality crystals from TRAAK, the researchers used antibodies that targeted it to create a sort of scaffold to help guide the formation of crystals.

In the structural images revealed by this work, the researchers found a unique system is responsible for holding off the flow of ions. TRAAK’s central cavity, through which the ions must pass, is flanked by two spiral-shaped chains called helices. When both of these chains are kinked upward, the channel is open so potassium can leave the cell. But when one of these two chains relaxes downward, it uncovers a sort of side door into the center of the neuron membrane.

Neuron membranes, like all cell membranes, consist of two layers of molecules called lipids that have heads facing outward and greasy chains extending inward. When TRAAK’s side door is open, one of those greasy chains, called an acyl chain, pokes into TRAAK’s central cavity, blocking it so no potassium can pass. No known channel uses a mechanism like this.

“This is the first time anyone has seen, at a molecular level, how mechanical force can open a channel in animals, including humans,” Brohawn says. “When the membrane stretches, TRAAK widens, sort of like a dot on a balloon that expands as it is inflated. That wider conformation pulls the helices upward, preventing an acyl chain from blocking the channel, and so leaving it open for potassium ions.”

“The direct involvement of lipid molecules in the gating mechanism begins to explain another well-known property of TRAAK channels – that their gating is sensitive to general anesthetics and other molecules known to enter the lipid membrane where they insert themselves between its acyl chains. By doing so, it appears these anesthetics can shut down pain sensations by locking TRAAK in an open position,” MacKinnon says.

Researchers map quantum vortices inside superfluid helium nanodroplets

First ever snapshots of spinning nanodroplets reveal surprising features

Scientists have, for the first time, characterized so-called quantum vortices that swirl within tiny droplets of liquid helium. The research, led by scientists at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), the University of Southern California, and SLAC National Accelerator Laboratory, confirms that helium nanodroplets are in fact the smallest possible superfluidic objects and opens new avenues to study quantum rotation.

“The observation of quantum vortices is one of the most clear and unique demonstrations of the quantum properties of these microscopic objects,” says Oliver Gessner, senior scientist in the Chemical Sciences Division at Berkeley Lab. Gessner and colleagues, Andrey Vilesov of the University of Southern California and Christoph Bostedt of SLAC National Accelerator Laboratory at Stanford, led the multi-facility and multi-university team that published the work this week in Science.

The finding could have implications for other liquid or gas systems that contain vortices, says USC’s Vilesov. “The quest for quantum vortices in superfluid droplets has stretched for decades,” he says. “But this is the first time they have been seen in superfluid droplets.”

Superfluid helium has long captured scientist’s imagination since its discovery in the 1930s. Unlike normal fluids, superfluids have no viscosity, a feature that leads to strange and sometimes unexpected properties such as crawling up the walls of containers or dripping through barriers that contained the liquid before it transitioned to a superfluid.

Helium superfluidity can be achieved when helium is cooled to near absolute zero (zero kelvin or about -460 degrees F). At this temperature, the atoms within the liquid no longer vibrate with heat energy and instead settle into a calm state in which all atoms act together in unison, as if they were a single particle.

For decades, researchers have known that when superfluid helium is rotated–in a little spinning bucket, say–the rotation produces quantum vortices, swirls that are regularly spaced throughout the liquid. But the question remained whether anyone could see this behavior in an isolated, nanoscale droplet. If the swirls were there, it would confirm that helium nanodroplets, which can range in size from tens of nanometers to microns, are indeed superfluid throughout and that the motion of the entire liquid drop is that of a single quantum object rather than a mixture of independent particles.

But measuring liquid flow in helium nanodroplets has proven to be a serious challenge. “The way these droplets are made is by passing helium through a tiny nozzle that is cryogenically cooled down to below 10 Kelvin,” says Gessner. “Then, the nanoscale droplets shoot through a vacuum chamber at almost 200 meters-per-second. They live once for a few milliseconds while traversing the experimental chamber and then they’re gone. How do you show that these objects, which are all different from one another, have quantum vortices inside?”

The researchers turned to a facility at SLAC called the Linac Coherent Light Source (LCLS), a DOE Office of Science user facility that is the world’s first x-ray free-electron laser. This laser produces very short light pulses, lasting just a ten-trillionth of a second, which contain a huge number of high-energy photons. These intense x-ray pulses can effectively take snapshots of single, ultra-fast, ultra-small objects and phenomena.

“With the new x-ray free electron laser, we can now image phenomenon and look at processes far beyond what we could imagine just a decade ago,” says Bostedt of SLAC. “Looking at the droplets gave us a beautiful glimpse into the quantum world. It really opens the door to fascinating sciences.”

In the experiment, the researchers blasted a stream of helium nanodroplets across the x-ray laser beam inside a vacuum chamber; a detector caught the pattern that formed when the x-ray light diffracted off the drops.

The diffraction patterns immediately revealed that the shape of many droplets were not spheres, as was previously assumed. Instead, they were oblate. Just as the Earth’s rotation causes it to bulge at the equator, so too do rotating nanodroplets expand around the middle and flatten at the top and bottom.

But the vortices themselves are invisible to x-ray diffraction, so the researchers used a trick of adding xenon atoms to the droplets. The xenon atoms get pulled into the vortices and cluster together.

“It’s similar to pulling the plug in a bathtub and watching the kids’ toys gather in the vortex,” says Gessner. The xenon atoms diffract x-ray light much stronger than the surrounding helium, making the regular arrays of vortices inside the droplet visible. In this way, the researchers confirmed that vortices in nanodroplets behave as those found in larger amounts of rotating superfluid helium.

Armed with this new information, the researchers were able to determine the rotational speed of the nanodroplets. They were surprised to find that the nanodroplets spin up to 100,000 times faster than any other superfluid helium sample ever studied in a laboratory.

Moreover, while normal liquid drops will change shape as they spin faster and faster–to resemble a peanut or multi-lobed globule, for instance–the researchers saw no evidence of such shapeshifting in the helium nanodroplets. “Essentially, we’re exploring a new regime of quantum rotation with this matter,” Gessner says.

“It’s a new kind of matter in a sense because it is a self-contained isolated superfluid,” he adds. “It’s just all by itself, held together by its own surface tension. It’s pretty perfect to study these system


IMAGE…This is an illustration of analysis of superfluid helium nanodroplets. Droplets are emitted via a cooled nozzle (upper right) and probed with x-ray from the free-electron laser. The multicolored pattern (upper left) represents a diffraction pattern that reveals the shape of a droplet and the presence of quantum vortices such as those represented in the turquoise circle with swirls (bottom center).

Credit: Felix P. Sturm and Daniel S. Slaughter, Berkeley Lab.

The first diffraction pattern from the brightest synchrotron light source in the world is here! The electrons whizzing around at nearly the speed of light at Brookhaven’s National Synchrotron Light Source II create a high-energy x-ray beam, which was steered toward a sample of sulfur-doped tantalum selenide just yesterday. When the beam hits the sample, the x-rays scatter off the atoms within the material, creating this gorgeous array of rings. 

This special compound has a strange characteristic: At low temperatures, electrons in both the pure tantalum selenide and sulfur-doped tantalum compounds spontaneously form into charge density waves, like ripples on the surface of a pond. These ripples have different wavelengths, and when they cross over one another, instead of canceling out electronic activity, they surprisingly create superconductivity – the pure lossless transfer of electricity.  

“It is like mixing red paint and white paint, and instead of getting pink you get blue after mixing,” said professor Simon Billinge, joint appointee with Brookhaven and Columbia University. Data from the X-ray Powder Diffraction beamline will help us understand how charge density waves in materials may lead to superconductivity. That’s super important for our nation’s energy future, but it also means we’ll have some more beautiful diffraction patterns to gaze at. Lucky us. 

I finally found a solvent mixture that can be used to crystallize one of the most interesting thermofluorescent compound (it changes it’s emission under UV light when cooled or warmed). Now I only need to grow small single crystals for an X-ray diffraction to know the exact structure of this compound.

Want to know a bit more about thermofluorescence? Just check out these posts: http://labphoto.tumblr.com/tagged/thermofluorescence

mr-cappadocia  asked:

I loved that deceptive as fuck post you made about Rosalind Franklin. She wasn't awarded the Nobel prize was because she was *dead*. You have to be *alive* to win the Nobel Prize. There's other important bits you "forgot". Photo 51, for example, wasn't even taken by her but by Gosling, who was working under Wilkins at time he shared the photo WITHOUT HER CONSENT!!! Look, I understand you're a Feminist so you need to lie fucking endlessly and shit on men at every opportunity, but I mean come on.

Hi there - I loved your sarcastic as fuck praise an equal amount! :)

I said in the first paragraph she was dead by the time the Nobel was awarded.

Photo 51 was developed by Gosling under her supervision - she had come in with the X-ray diffraction expertise from her previous work, had trained him up, and was working with him. He was working for her. I can understand if you are saying that Gosling should get full credit, but that is a debatable point, and one on which I don’t agree. 

Gosling was not the one to share the photo.

I indicated a lack of consent on her part in the writeup.


Look, these writeups are long and about complicated subjects. I abbreviate stories (like the work behind Photo 51) because the writeups are long enough as is. I wrote badly of Wilkins, Crick, and Watson because they did dishonorable things. Wilkins and Crick, I noted, made up for it and tried to salvage her name. Watson, less so.

Lastly, my sympathies on not liking the entry, and I understand you seemingly have some strong ideological objections to the entire idea for this project. However. If you’re going to approach me, please do so in a more measured fashion. I’m a human being. I have a long history of amending and updating my words when I get something wrong. I don’t have a lot of ego about this. But coming at me with insults is not the way to start a dialogue.