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Category: nanotechnology – Page 113

Similar in function to ballast tanks in submarines or fish bladders, many water-based bacteria use gas vesicles to regulate their floatability. In a new publication in Cell, scientists from the Departments of Bionanoscience and Imaging Physics now describe the molecular structure of these vesicles for the first time. These gas vesicles were also recently repurposed as contrast agents for ultrasound imaging.

Gas vesicles (GVs) are hollow, cylindrical nanostructures made of a thin protein-based shell and filled with gas. Similar in function to ballast tanks in submarines or fish bladders, many water-based bacteria use these structures to regulate their floatability. “For example, certain cyanobacteria use gas vesicles to float to the surface in order to harvest light for photosynthesis, a phenomenon sometimes seen at enormous scale in toxic algal blooms,” says Arjen Jakobi, Assistant Professor at the Department of Bionanoscience.

There are very specific requirements for such structures: for bacteria to stay afloat, GVs must occupy a substantial proportion of the cell, which involves forming compartments that extend over hundreds of nanometers in size. To maximize floatability, the shell must be constructed from minimal material. At the same time, the shell needs to provide resistance to the pressure from the surrounding water to maintain the ability to float with changes in water depth. GVs have therefore evolved as rigid, thin-walled structures composed of a single protein that repeats many thousands of times to form the GV shell.

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Glass nanoparticles trapped by lasers in extreme vacuum are considered a promising platform for exploring the limits of the quantum world. Since the advent of quantum theory, the question at which sizes an object starts being described by the laws of quantum physics rather than the rules of classical physics has remained unanswered.

A team formed by Lukas Novotny (ETH Zurich), Markus Aspelmeyer (University of Vienna), Oriol Romero-Isart (University of Innsbruck), and Romain Quidant (Zurich) is attempting to answer precisely this question within the ERC-Synergy project Q-Xtreme. A crucial step on the way to this goal is to reduce the energy stored in the motion of the nanoparticle as much as possible, i.e. to cool the particle down to the so-called quantum ground-state.

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Lipid nanoparticles (LNPs) transport small molecules into the body. The most well-known LNP cargo is mRNA, the key constituent of some of the early vaccines against COVID-19. But that is just one application: LNPs can carry many different types of payload, and have applications beyond vaccines.

Barbara Mui has been working on LNPs (and their predecessors, liposomes) since she was a PhD student in Pieter Cullis’s group in the 1990s. “In those days, LNPs encapsulated anti-cancer drugs,” says Mui, who is currently a senior scientist at Acuitas, the company that developed the LNPs used in the Pfizer-BioNTech mRNA vaccine against SARS-CoV-2. She says it soon became clear that LNPs worked even better as carriers of polynucleotides. “The first one that worked really well was encapsulating small RNAs,” Mui recalls.

But it was mRNA where LNPs proved most effective, primarily because LNPs are comprised of positively charged lipid nanoparticles that encapsulate negatively charged mRNA. Once in the body, LNPs enter cells via endocytosis into endosomes and are released into the cytoplasm. “Without the specially designed chemistry, the LNP and mRNA would be degraded in the endosome,” says Kathryn Whitehead, professor in the departments of chemical engineering and biomedical engineering at Carnegie Mellon University.

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Experts consider glass nanoparticles kept inside extreme vacuum layers as potential platforms for examining the quantum world’s limits. However, a question in the field of quantum theory remains unanswered: at which size does an object start being described by quantum physics laws rather than classical physics laws?

Achieving Quantum-State Cooling in More Than One Direction Is Challenging

SciTechDaily reports that a research team attempted to precisely answer the question through the ERC-Synergy project Q-Xtreme. The team comprised Lukas Novotny from ETH Zurich, Markus Aspelmeyer from the University of Vienna, Oriol Romero-Isart from the University of Innsbruck, and Romain Quidant from Zurich.

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The soot produced by unburnt hydrocarbon flames is the second largest contributor to global warming, while also harming human health. Researchers have developed state-of-the-art, high-speed imaging techniques to study turbulent flames, yet they are limited to an imaging rate of million-frames-per-second. Physicists are therefore keen to obtain a complete picture of flame-laser interactions via single-pulse imaging.

In a new report published in Light: Science & Applications, Yogeshwar Nath Mishra and a research team at the Caltech Optical Imaging Laboratory, the NASA Jet propulsion lab, department of physics, and the Institute of Engineering Thermodynamics in the U.S., and Germany, used single-shot laser-sheet comprised ultrafast photography per billion frames per second, for the first time, to observe the dynamics of laser-flames.

The team noted laser-induced incandescence, elastic light scattering and the fluorescence of soot precursors such as polycyclic aromatic hydrocarbons in , with a single nanosecond laser pulse. The research outcomes provide strong experimental evidence to support soot inception and growth mechanisms in flames. Mishra and the team combined a variety of techniques to probe the short-lived species in turbulent environments to unravel the mysteries of hot plasma, nuclear fusion and sonoluminescence.

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Scientists are vigorously competing to transform the counterintuitive discoveries about the quantum realm from a century past into technologies of the future. The building block in these technologies is the quantum bit, or qubit. Several different kinds are under development, including ones that use defects within the symmetrical structures of diamond and silicon. They may one day transform computing, accelerate drug discovery, generate unhackable networks and more.

Working with researchers from several universities, scientists at the U.S. Department of Energy’s (DOE) Argonne National Laboratory have discovered a method for introducing spinning electrons as qubits in a host nanomaterial. Their test results revealed record long coherence times—the key property for any practical qubit because it defines the number of quantum operations that can be performed in the lifetime of the qubit.

Electrons have a property analogous to the spin of a top, with a key difference. When tops spin in place, they can rotate to the right or left. Electrons can behave as though they were rotating in both directions at the same time. This is a quantum feature called superposition. Being in two states at the same time makes electrons good candidates for spin qubits.

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Carbon nanotubes (CNTs) are cylindrical tube-like structures made of carbon atoms that display highly desirable physical properties like high strength, low weight, and excellent thermal and electrical conductivities. This makes them ideal materials for various applications, including reinforcement materials, energy storage and conversion devices, and electronics.

Despite such immense potential, however, there have been challenges in commercializing CNTs, such as their incorporation on plastic substrates for fabricating flexible CNT-based devices. Traditional fabrication methods require carefully controlled environments such as high temperatures and a clean room. Further, they require repeat transfers to produce CNTs with different resistance values.

More direct methods such as laser-induced forward transfer (LIFT) and thermal fusion (TF) have been developed as alternatives. In the LIFT method, a laser is used to directly transfer CNTs onto substrates, while in TF, CNTs are mixed with polymers that are then selectively removed by a laser to form CNT wires with varying resistance values.

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Skyrmions are extremely small with diameters in the nanoscale, and they behave as particles suited for information storage and logic technologies. In 1961, Tony Skyrme formulated a manifestation of the first topological defect to model a particle and coined it as skyrmions. Such particles with topologically stable configurations can launch a promising route toward establishing high-density magnetic and phononic (a discrete unit of quantum vibrational mechanical energy) information processing routes.

In a new report published in Science Advances, Liyun Cao and a team of researchers at the University of Lorraine CNRS, France, experimentally developed phononic skyrmions as new topological structures by using the three-dimensional (3D) hybrid spin of . The researchers observed the frequency-independent spin configurations and their progression toward the formation of ultra-broadband phononic skyrmions that could be produced on any solid structure.

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The RNA molecule is commonly recognized as messenger between DNA and protein, but it can also be folded into intricate molecular machines. An example of a naturally occurring RNA machine is the ribosome, that functions as a protein factory in all cells.

Inspired by natural RNA machines, researchers at the Interdisciplinary Nanoscience Center (iNANO) have developed a method called “RNA origami,” which makes it possible to design artificial RNA nanostructures that fold from a single stand of RNA. The method is inspired by the Japanese paper folding art, origami, where a single piece of paper can be folded into a given shape, such as a paper bird.

The in Nature Nanotechnology describes how the RNA origami technique was used to design RNA nanostructures, that were characterized by cryo– (cryo-EM) at the Danish National cryo-EM Facility EMBION. Cryo-EM is a method for determining the 3D structure of biomolecules, which works by freezing the sample so quickly that water does not have time to form ice crystals, which means that frozen biomolecules can be observed more clearly with the electron microscope.

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