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Category: chemistry

Nuclear physicists make new, high-precision measurement of the layer of neutrons that encompass the lead nucleus, revealing new information about neutron stars.

Nuclear physicists have made a new, highly accurate measurement of the thickness of the neutron “skin” that encompasses the lead nucleus in experiments conducted at the U.S. Department of Energy’s Thomas Jefferson National Accelerator Facility and just published in Physical Review Letters. The result, which revealed a neutron skin thickness of .28 millionths of a nanometer, has important implications for the structure and size of neutron stars.

The protons and neutrons that form the nucleus at the heart of every atom in the universe help determine each atom’s identity and properties. Nuclear physicists are studying different nuclei to learn more about how these protons and neutrons act inside the nucleus. The Lead Radius Experiment collaboration, called PREx (after the chemical symbol for lead, Pb), is studying the fine details of how protons and neutrons are distributed in lead nuclei.

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Circa 2020 o.,.o!

By Leah Crane.

Google researchers have used a quantum computer to simulate a chemical reaction for the first time. The reaction is a simple one, but this marks a step towards finding a practical use for quantum computers.

Because atoms and molecules are systems governed by quantum mechanics, quantum computers are expected to be the best way to precisely simulate them. These computers use quantum bits, or qubits, to store information and perform calculations. However, quantum computers have difficulty achieving the precision needed to simulate large atoms or chemical reactions.

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Nuclear physicists have made a new, highly accurate measurement of the thickness of the neutron “skin” that encompasses the lead nucleus in experiments conducted at the U.S. Department of Energy’s Thomas Jefferson National Accelerator Facility and just published in Physical Review Letters. The result, which revealed a neutron skin thickness of .28 millionths of a nanometer, has important implications for the structure and size of neutron stars.

The protons and neutrons that form the nucleus at the heart of every atom in the universe help determine each atom’s identity and properties. Nuclear physicists are studying different nuclei to learn more about how these protons and neutrons act inside the nucleus. The Lead Radius Experiment collaboration, called PREx (after the chemical symbol for lead, Pb), is studying the fine details of how protons and neutrons are distributed in lead nuclei.

“The question is about where the neutrons are in lead. Lead is a heavy nucleus—there’s extra neutrons, but as far as the is concerned, an equal mix of protons and neutrons works better,” said Kent Paschke, a professor at the University of Virginia and experiment co-spokesperson.

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A person can weed about one acre of crops a day. This smart robot can weed 20.

Carbon Robotics has unveiled the third-generation of its Autonomous Weeder, a smart farming robot that identifies weeds and then destroys them with high-power lasers.

The weedkiller challenge: Weeds compete with plants for space, sunlight, and soil nutrients. They can also make it easier for insect pests to harm crops, so weed control is a top concern for farmers.

Chemical herbicides can kill the pesky plants, but they can also contaminate water and affect soil health. Weeds can be pulled out by hand, but it’s unpleasant work, and labor shortages are already a huge problem in the agriculture industry.

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Others think we’re still missing fundamental aspects of how intelligence works, and that the best way to fill the gaps is to borrow from nature. For many that means building “neuromorphic” hardware that more closely mimics the architecture and operation of biological brains.

The problem is that the existing computer technology we have at our disposal looks very different from biological information processing systems, and operates on completely different principles. For a start, modern computers are digital and neurons are analog. And although both rely on electrical signals, they come in very different flavors, and the brain also uses a host of chemical signals to carry out processing.

Now though, researchers at NIST think they’ve found a way to combine existing technologies in a way that could mimic the core attributes of the brain. Using their approach, they outline a blueprint for a “neuromorphic supercomputer” that could not only match, but surpass the physical limits of biological systems.

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Li-ion batteries and other emerging lithium-based battery technologies are currently used to power a wide range of devices, including smartphones, laptops, tablets and cameras. Despite their advantages, batteries containing lithium do not always retain their performance over time.

One of the main reasons for the performance decay observed in some Li-based batteries is that the lithium contained within them sometimes becomes inactive or “dead.” This “dead lithium” can cause capacity decay and thermal runaway, which can ultimately reduce a battery’s lifespan and impair its performance.

Researchers at Zhejiang University of Technology in China and Argonne National Laboratory in the U.S. have recently devised a strategy to restore inactive lithium in Li anodes. This strategy, outlined in a paper published in Nature Energy, is based on a chemical reaction known as iodine redox.

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Circa 2019

To create neutrons in the high flux neutron generator, UC Berkeley researchers heat up deuterium atoms in a vacuum chamber to 50000 degrees Celsius to obtain an ionized plasma (pink glow), then accelerate the ions until they collide and fuse with other deuterium atoms implanted in the titanium cathode, releasing neutrons in the process. The spiral coil is the water-cooled radio-frequency antenna that heats the plasma, viewed through a quartz window into the vacuum chamber. (UC Berkeley photo by Cory Waltz)

In an underground vault enclosed by six-foot concrete walls and accessed by a rolling, 25-ton concrete-and-steel door, University of California, Berkeley, students are making neutrons dance to a new tune: one better suited to producing isotopes required for geological dating, police forensics, hospital diagnosis and treatment.

Dating and forensics rely on a spray of neutrons to convert atoms to radioactive isotopes, which betray the chemical composition of a substance, helping to trace a gun or reveal the age of a rock, for example. Hospitals use isotopes produced by neutron irradiation to kill tumors or pinpoint diseases like cancer in the body.

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Levitation has long been a staple of magic tricks and movies. But in the lab, it’s no trick. Scientists can levitate droplets of liquid, though mixing them and observing the reactions has been challenging. The pay-off, however, could be big as it would allow researchers to conduct contact-free experiments without containers or handling that might affect the outcome. Now, a team reporting in ACS’ Analytical Chemistry has developed a method to do just that.

Scientists have made devices to levitate small objects, but most methods require the object to have certain physical properties, such as electric charge or magnetism. In contrast, acoustic levitation, which uses sound waves to suspend an object in a gas, doesn’t rely on such properties. Yet existing devices for acoustic levitation and mixing of single particles or droplets are complex, and it is difficult to obtain measurements from them as a chemical reaction is happening. Stephen Brotton and Ralf Kaiser wanted to develop a versatile technique for the contactless control of two chemically distinct droplets, with a set of probes to follow the reaction as the droplets merge.

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Phosphorus, the element critical for life´s origin and life on Earth, may be even Venus.

Scientists studying the origin of life in the universe often focus on a few critical elements, particularly carbon, hydrogen, and oxygen. But two new papers highlight the importance of phosphorus for biology: an assessment of where things stand with a recent claim about possible life in the clouds of Venus, and a look at how reduced phosphorus compounds produced by lightning might have been critical for life early in our own planet’s history.

First a little biochemistry: Phosphine is a reduced phosphorus compound with one phosphorus atom and three hydrogen atoms. Phosphorus is also found in its reduced form in the phosphide mineral schreibersite, in which the phosphorus atom binds to three metal atoms (either iron or nickel). In its reduced form, phosphorus is much more reactive and useful for life than is phosphate, where the phosphorus atom binds to four oxygen atoms. Phosphorus is also the element that is most enriched in biological molecules as compared to non-biological molecules, so it’s not a bad place to start when you’re hunting for life.

In the second of the new papers, Benjamin Hess from Yale University and colleagues highlight the contribution of lightning as a source of reduced phosphorus compounds such as schreibersite. It has long been recognized that meteorites supplied much of the reduced phosphorus needed for the origin of life on Earth. But Hess thinks the contribution of lightning has been underestimated. For one thing, lightning was much more common early in our planet’s history. The authors calculate that it could have produced up to 10000 kilograms of reduced phosphorus compounds per year—which may have been enough to jump-start life, especially because we don’t know how much of the reduced phosphorus from meteorites actually survives (in that form) the impact on Earth.

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