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Category: chemistry – Page 250

Probability of a reaction occurring increases 100-fold and points to quantum control of chemistry.

A new step towards quantum control of chemistry has been achieved by researchers in the US, who found that tuning the magnetic field applied to colliding ultracold molecules could alter the probability of them reacting or undergoing inelastic scattering a 100-fold.1 The work could potentially prove useful for producing large ensembles of molecules in the same state and investigating their properties.

At room temperature, the random thermal motion of atoms and molecules blurs the quantum nature of chemistry. In an ultracold regime, however, this thermal motion is stilled, revealing chemical interactions as quantum interference processes between matter waves. Remarkable phenomena have been seen in ultracold atomic gases, such as the creation of Bose–Einstein condensates, in which atoms all enter the quantum ground state of a trap, allowing a macroscopic view of their quantum wavefunction. Wolfgang Ketterle at the Massachusetts Institute of Technology (MIT), whose group performed the new research, shared the 2001 physics Nobel prize for the creation of this condensate.

Cooling molecules to the ground state of a trap is much trickier than cooling atoms because they can contain thermal energy in so many internal degrees of freedom, and was only achieved by Jun Ye of JILA in the US and colleagues recently.2 In 2020, Ye’s group applied an electric field to potassium–rubidium molecules, which decay into diatomic potassium and rubidium molecules. The researchers showed that, at a specific field, the molecules were excited into states forbidden by quantum mechanics and could get close enough to react. This drastically slowed the decay rate. ‘For our system, we typically think that, if the two molecules get very close together, there is close to a 100% chance that they will undergo a chemical reaction,’ explains Kyle Matsuda, Ye’s PhD student and the 2020 paper’s lead author.

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Papers referenced in the video:
Association between low-density lipoprotein cholesterol and cardiovascular mortality in statin non-users: a prospective cohort study in 14.9 million Korean adults.
https://pubmed.ncbi.nlm.nih.gov/35218344/

Relationship between serum non-high-density lipoprotein cholesterol and incidence of cardiovascular disease.
https://pubmed.ncbi.nlm.nih.gov/21176640/

Non-HDL cholesterol paradox and effect of underlying malnutrition in patients with coronary artery disease: A 41,182 cohort study.
https://pubmed.ncbi.nlm.nih.gov/35168005/

Age and sex variation in serum albumin concentration: an observational study.
https://pubmed.ncbi.nlm.nih.gov/26071488/

Commonly used clinical chemistry tests as mortality predictors: Results from two large cohort studies.

Continue reading “The Association For Low LDL With An Increased CVD Mortality Risk Is Impacted” | >

Researchers at North Carolina State University have developed a new computational tool that allows users to conduct simulations of multi-functional magnetic nanoparticles in unprecedented detail. The advance paves the way for new work aimed at developing magnetic nanoparticles for use in applications from drug delivery to sensor technologies.

“Self-assembling , or MNPs, have a lot of desirable properties,” says Yaroslava Yingling, corresponding author of a paper on the work and a Distinguished Professor of Materials Science and Engineering at NC State. “But it has been challenging to study them, because computational models have struggled to account for all of the forces that can influence these materials. MNPs are subject to a complicated interplay between external magnetic fields and van der Waals, electrostatic, dipolar, steric, and .”

Many applications of MNPs require an understanding of how the nanoparticles will behave in complex environments, such as using MNPs to deliver a specific protein or drug molecule to a targeted cancer affected cell using external magnetic fields. In these cases, it is important to be able to accurately model how MNPs will respond to different chemical environments. Previous computational modeling techniques that looked at MNPs were unable to account for all of the chemical interactions MNPs experience in a given colloidal or biological environment, instead focusing primarily on physical interactions.

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The human brain, fed on just the calorie input of a modest diet, easily outperforms state-of-the-art supercomputers powered by full-scale station energy inputs. The difference stems from the multiple states of brain processes versus the two binary states of digital processors, as well as the ability to store information without power consumption—non-volatile memory. These inefficiencies in today’s conventional computers have prompted great interest in developing synthetic synapses for use in computers that can mimic the way the brain works. Now, researchers at King’s College London, UK, report in ACS Nano Letters an array of nanorod devices that mimic the brain more closely than ever before. The devices may find applications in artificial neural networks.

Efforts to emulate biological synapses have revolved around types of memristors with different resistance states that act like memory. However, unlike the the devices reported so far have all needed a reverse polarity to reset them to the initial state. “In the brain a change in the changes the output,” explains Anatoly Zayats, a professor at King’s College London who led the team behind the recent results. The King’s College London researchers have now been able to demonstrate this brain-like behavior in their synaptic synapses as well.

Zayats and team build an array of gold nanorods topped with a polymer junction (poly-L-histidine, PLH) to a metal contact. Either light or an electrical voltage can excite plasmons—collective oscillations of electrons. The plasmons release hot electrons into the PLH, gradually changing the chemistry of the polymer, and hence changing it to have different levels of conductivity or light emissivity. How the polymer changes depends on whether oxygen or hydrogen surrounds it. A chemically inert nitrogen chemical environment will preserve the state without any energy input required so that it acts as non-volatile memory.

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The development of functional nanomaterials has been a major landmark in the history of materials science. Nanoparticles with diameters ranging from 5 to 500 nm have unprecedented properties, such as high catalytic activity, compared to their bulk material counterparts. Moreover, as particles become smaller, exotic quantum phenomena become more prominent. This has enabled scientists to produce materials and devices with characteristics that had been only dreamed of, especially in the fields of electronics, catalysis, and optics.

But what if we go smaller? Sub-nanoparticles (SNPs) with particle sizes of around 1 nm are now considered a new class of materials with distinct properties due to the predominance of quantum effects. The untapped potential of SNPs caught the attention of scientists from Tokyo Tech, who are currently undertaking the challenges arising in this mostly unexplored field. In a recent study published in the Journal of the American Chemical Society, a team of scientists from the Laboratory of Chemistry and Life Sciences, led by Dr. Takamasa Tsukamoto, demonstrated a novel molecular screening approach to find promising SNPs.

As one would expect, the synthesis of SNPs is plagued by technical difficulties, even more so for those containing multiple elements. Dr. Tsukamoto explains: “Even SNPs containing just two different elements have barely been investigated because producing a system of subnanometer scale requires fine control of the composition ratio and particle size with atomic precision.” However, this team of scientists had already developed a novel method by which SNPs could be made from different metal salts with extreme control over the total number of atoms and the proportion of each element.

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The team noted that although other studies have been able to create nephrons and ureteric ducts from stem cells, these didn’t fully function as they would in real kidneys due to the absence of stromal cells, which are crucial for cell signaling. The team took embryonic stem cells from mice and induced these to differentiate into kidney-specific stromal cells, using a cocktail of chemicals meant to mimic those that would occur in vivo.

When they combined the stromal cells with nephron and ureteric bud cells (which they also created from stem cells), the result was a “kidney-like 3D tissue, consisting of extensively branched tubules and several other kidney-specific structures.”

According to the researchers, this is the most complex kidney structure that’s been generated from scratch in a lab. Though this study was done in mice, the team noted that it has already created the first two kidney components—nephron progenitors and ureteric buds—from human induced pluripotent stem cells (iPSCs). If they’re able to also create stromal cells from iPSCs, they said, “a similarly complex human kidney should be achievable.”

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Picture yourself hovering over an alien city with billions of blinking lights of thousands of types, with the task of figuring out which ones are connected, which way the electricity flows and how that translates into nightlife. Welcome to the deep brain.

Even in an era rapidly becoming known as the heyday of neuroscience, tracing the biochemical signaling among billions of neurons deep in the brain has remained elusive and baffling.

A team of Stanford University researchers managed to map out one such connection, buried inside the brain of a living, moving mammal as they manipulated its behavior. The feat offers an unprecedented close-up of the genesis of on a cellular level, and could offer insights into psychiatric puzzles such as autism, depression and anxiety.

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An analysis of radioactive chemicals in ice cores indicates one of the most powerful solar storms ever hit Earth around 7,176 B.C.

(Inside Science) — For a few nights more than 9,000 years ago, at a time when many of our ancestors were wearing animal skins, the northern skies would have been bright with flickering lights.

Telltale chemical isotopes in ancient ice cores suggest one of the most massive solar storms ever took place around 7,176 B.C., and it would have been noticed.

“We know that most high-energy events are accompanied by geomagnetic storms,” said Raimund Muscheler, a professor of geology at Sweden’s Lund University. “So it’s likely that there were visible auroras.”

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Scientists from the Max Planck Institute for Polymer Research, Paderborn University, and the University of Konstanz have succeeded in achieving a rare quantum state. They are the first to have demonstrated Wannier-Stark localization in a polycrystalline substance. Predicted around 80 years ago, the effect has only recently been proven — in a monocrystal. Until now, researchers assumed this localization to be possible only in such monocrystalline substances which are very complicated to produce. The new findings represent a breakthrough in the field of physics and could in future give rise to new optical modulators, for example, that can be used in information technologies based on light, among other things. The physicists have published their findings in the well-respected technical journal, Nature Communications.

Stronger and faster than lightning

The atoms of a crystal are arranged in a three-dimensional grid, held together by chemical bonds. These bonds can, however, be dissolved by very strong electric fields which displace atoms, even going so far as to introduce so much energy into the crystal that it is destroyed. This is what happens when lightning strikes and materials liquefy, vaporize or combust, for example. To demonstrate Wannier-Stark localization, the scientists’ experiments involved setting up electric fields of several million volts per centimeter, much stronger than the fields involved in lightning strikes. During this process, the electronic system of a solid — in this case, a polycrystal — is forced far from a state of equilibrium for a very short time. Wannier-Stark localization involves virtually shutting down some of the chemical bonds temporarily. This state can only be maintained for less than a picosecond — one millionth of one millionth of a second — without destroying the substance.

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Hydrogen is already a key component of chemical industrial processes and in the steel industry. So making clean hydrogen to use in those industrial processes is critical to reducing carbon emissions, says Jake Stones at market research firm Independent Commodity Intelligence Services (ICIS).

But as an energy source itself, hydrogen’s big advantage is its versatility according to Sunita Satyapal, who oversees hydrogen fuel cell technology for the Department of Energy.

“It’s often called the Swiss Army knife of energy,” she says.

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