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Researchers Observe Nanoparticles Ripening in Solution at Record-Breaking Resolution – AZoNano

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A textbook process called “Ostwald ripening,” named after the Nobel Prize-winning chemist Wilhelm Ostwald, has directed the design of new materials such as nanoparticles for decades. These are tiny materials that appear to be so small that they are not visible to the naked eye.

New video footage captured by Berkeley Lab scientists reveals for the first time that nanoparticle growth is directed not by difference in size, but by defects. Image Credit: Haimei Zheng/Berkeley Lab. Courtesy of Nature Communications.

As per this theory, small particles dissolve and then redeposit onto the surface of huge particles, and the large particles continue to grow until all of the small particles have dissolved.

But at present, new video footage that has been captured by Berkeley Lab researchers discloses that nanoparticle growth has been directed not by differences in size but by flaws.

The scientists recently reported their findings in the Nature Communications journal.

This is a huge milestone. We are rewriting textbook chemistry, and it’s very exciting.

Haimei Zheng, Study Senior Author and Adjunct Professor, Materials Science and Engineering, University of California, Berkeley

Zheng is also a senior scientist in the materials sciences division in Berkeley Lab.

For the study, the scientists suspended a solution of cadmium sulfide (CdS) nanoparticles with hydrogen chloride (HCl) and cadmium chloride (CdCl2) in a custom liquid sample holder.

The scientists uncovered the solution with an electron beam to generate Cd-CdCl2 core-shell nanoparticles (CSNPs) — which appeared to look like a flat, hexagonal disc where cadmium chloride forms the shell and cadmium atoms develop the core.

With the help of a new method known as high-resolution liquid cell transmission electron microscopy (LC-TEM) at the Molecular Foundry, the scientists captured real-time and atomic-scale LC-TEM videos of Cd-CdCl2 CSNPs maturing in solution.

In one of the experiments, an LC-TEM video displays a small Cd-CdCl2 core-shell nanoparticle blending with a huge Cd-CdCl2 CSNP to develop a bigger Cd-CdCl2 CSNP. But the direction of growth was headed not by a variation in size but by a crack defect in the shell of the initially bigger CSNP.

The finding was very unexpected, but we’re very happy with the results.

Qiubo Zhang, Study First Author and Postdoctoral Researcher, Materials Sciences Division, University of California, Berkeley

The scientists state that their work is the highest resolution LC-TEM video that has ever been recorded. The progress — tracking how nanoparticles ripen in solution in real time — was made possible by a custom-made and ultrathin “liquid cell” that holds a small amount of liquid between two carbon-film membranes on a copper grid.

The scientists observed the liquid sample through ThemIS, a specific electron microscope at the Molecular Foundry that has the potential to record atomic-scale variations in liquids at a speed range of 40 to 400 frames per second. The high-vacuum environment of the microscope helps keep the liquid sample intact.

Our study fills in the gap for nanomaterial transformations that can’t be predicted by traditional theory. I hope our work inspires others to think of new rules to design functional nanomaterials for new applications.

Haimei Zheng, Study Senior Author and Adjunct Professor, Materials Science and Engineering, University of California, Berkeley

Zheng pioneered LC-TEM at Berkeley Lab in 2009 and is also a leading expert in the field.

Journal Reference:

Zhang, Q., et al. (2022) Defect-mediated ripening of core-shell nanostructures. Nature Communications. doi.org/10.1038/s41467-022-29847-8.

Source: https://www.lbl.gov/

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Jupiter will be its brightest in 59 years Monday. Here's how to see it for yourself – CBC News

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You may have noticed a bright “star” in the eastern sky after sunset, but that’s no star: it’s the mighty planet Jupiter, and it’s almost at its peak brightness.

Jupiter, the largest planet in our solar system, is reaching opposition, an event that occurs when a celestial object rises in the east as the sun sets in the west, putting both the sun and the object on opposite sides of Earth.

But what also makes this special is that the planet will be the closest it has been to Earth in 59 years, meaning it will also be brighter than usual.

The reason planets vary in their distance from Earth is because their orbits aren’t perfectly circular, but rather slightly elliptical.

This image of Jupiter and its moons Io (lower left) and Ganymede (upper right) was acquired by amateur astronomer Damian Peach on Sept. 12, 2010, when Jupiter was close to opposition. South is up and the ‘Great Red Spot’ is visible in the image. (NASA/Damian Peach)

While Jupiter’s opposition happens roughly every 13 months, it’s not common for it to coincide with its closest approach, making this a particularly special treat.

How to see it

At its farthest, Jupiter can be as far as 966 million kilometres away, but on Monday, it will be about 591 million kilometres from Earth. The last time it was this close was in October 1963. And it won’t be this close again until 2129.

You can find the planet in the east after sunset. It’s hard to miss, even from a light-polluted city, as it is the brightest object in the sky. 

As the night progresses, it rises higher into the sky, eventually appearing in the southeast around 11 p.m. ET. on Monday.

You don’t need a telescope or binoculars to see it, but if you do have a pair of binoculars or a telescope, you can have some fun over the coming days. 

One of the special things about Jupiter is its four brightest moons: Callisto, Io, Ganymede and Europa. They orbit Jupiter in a timescale visible from Earth night after night, and even hour after hour — if you’re patient. 

This sky map shows the positions of four of Jupiter’s moons the following night of the opposition, on Sept. 27 at roughly 10:30 p.m. ET. (Stellarium)
This sky chart shows the positions of four of Jupiter’s 80 moons at 10:30 p.m. ET on Sept. 26. (Stellarium)

If you do have a telescope, you can view the moons — and the amazing cloud bands of the gaseous planet, which make for a stunning sight. Also, according to Sky & Telescope magazine, the Great Red Spot will begin its transit — or its crossing — at 8:44 p.m. ET Monday. You can find local times using the publication’s online app or find its app and others like it for your cellphone or tablet. 

Saturn will also be visible in the sky. It currently lies in the south around 10 p.m. ET, but it’s more difficult to spot as it’s not as bright as Jupiter.

You can find several free apps available for download on Android phones and iPhones — such as Stellarium, Star Walk and Sky View — that will help you identify what you see in the night sky, including planets and where to find them.

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NASA Will Crash A Spacecraft Into An Asteroid For Science! – Forbes

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NASA will intentionally crash a spacecraft into an orbiting asteroid at high speed in the coming hours. The DART mission will attempt to prove that an unmanned space probe can autonomously navigate to a target asteroid and intentionally collide with it. The technique, called kinetic impact, could be used to re-direct an asteroids that may pose a threat to Earth, should one ever be discovered.

NASA’s Double Asteroid Redirection Test – a first-of-its-kind experiment – will try to alter the orbit of one of two gravitationally bound asteroids in orbit around the Sun. This binary asteroid system is known as Didymos, and the smaller “moonlet” of the pair, Dimorphos, will be the first asteroid in the Solar System to be the target of a humanmade “kinetic impactor”.

The 1,2 x 1,3 x 1,3-meter space probe will intercept the Didymos system at 7:14 p.m. on Monday, with DART slamming into the 160-meters wide Dimorphos at roughly 6,6 kilometers per second a few hours later if everything goes as planned.

The target asteroid Dimorphos, orbiting the larger Didymos, poses no threat to Earth, and even a successful impact will alter its orbit by just 0,4 millimeters. Any changes in the orbital parameters will be precisely measured using telescopes on Earth. The experiment results will be used to validate and improve computer models for kinetic impacts.

In the last few hours of DART’s life, it will send a constant stream of images to Earth.

“This is an amazing moment for our space program,” so Elena Adams, the mission systems engineer at the Johns Hopkins Applied Physics Laboratory.

“For the first time, we will move a celestial body intentionally in space, beyond Earth orbit! This test goes beyond international borders, and really shows what we can accomplish if we all work together as one team and as one Earth.”

Material provided by the European Space Agency and NASA.

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Squirrels, volcanoes, and ancient DNA – TownAndCountryToday.com – Town and Country TODAY

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ATHABASCA — What does the research into ground squirrels dating back 50,000 years have to do with ancient DNA or volcanoes? 

Those are some of the fascinating details Scott Cocker, a paleoecologist and PhD student at the University of Alberta (U of A), will be discussing in a Zoom presentation hosted by Science Outreach – Athabasca Sept. 27 at 7 p.m. 

“I’m interested in the ground squirrels themselves because we jokingly refer to them as furry botanists,” Cocker said in a Sept. 15 interview. “They were grabbing plants; they were grabbing whatever they could grab before they went into hibernation. So, they would store all this stuff in their nest and then the nest is what we find 40,000 years later or whatever have you … frozen in the permafrost with all those seeds or with bones of other animals. They are basically like little archives of the Ice Age and Yukon.” 

Cocker realized while everyone was distracted by larger creatures like woolly mammoths and woolly rhinos, they didn’t offer as much information on life at the time as ground squirrel nests could. 

“The ecosystem and the environment, we call that the mammoth steppe and for a long time that’s what everyone referred to; the mammoth steppe this, the mammoth steppe that, and it’s just because the mammoths are big and charismatic,” he said. “But my whole thesis is that if you really want to understand the mammoth steppe and the environment that they were living in, you actually have to look to things like the ground squirrels because they tell us way more about the environment than the mammoths do.” 

Throw in some new sequencing of DNA which allows scientists to accurately identify a species from just small pieces of DNA. 

“In the last 20 years, it’s something that’s been developed,” he said. “We can work with modern DNA really easily because stranded DNA are in the count of millions … but once that organism dies and sits around for a while, then the DNA starts to degrade, and it breaks down over time and so we end up with these really short little pieces of DNA.” 

Then mix in the aftermath of a volcanic eruption in southern Alaska 25,000 years ago which covered the area with up to a metre of ash and it changes how all fauna lived and you have the basics of Cocker’s presentation. 

“How did that impact the animals and plants at the time of the eruption? Because it definitely was one of the largest in the last million years in this part of the world,” Cocker said. “It completely covered the plants. Think about (the) ground squirrels or the voles and mice and stuff that … rely on foraging and you’re half the size of the ash fall, you’re gonna struggle.” 

The link to the presentation can be found on the Science Outreach – Athabasca website and social media and will start at 7 p.m. Sept. 27. 

hstocking@athabasca.greatwest.ca 

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