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Category: nanotechnology – Page 198

Graphene’s unique 2-D structure means that electrons travel through it differently than in most other materials. One consequence of this unique transport is that applying a voltage doesn’t stop the electrons like it does in most other materials. This is a problem, because to make useful applications out of graphene and its unique electrons, such as quantum computers, it is necessary to be able to stop and control graphene electrons.

An interdisciplinary team of scientists from the Universidad Autonoma de Madrid (Spain), Université Grenoble Alpes (France), International Iberian Nanotechnology Laboratory (Portugal) and Aalto University has solved this long-standing problem. The team included experimental researchers Eva Cortés del Río, Pierre Mallet, Héctor González‐Herrero, José María Gómez‐Rodríguez, Jean‐Yves Veuillen and Iván Brihuega and theorists including Joaquín Fernández-Rossier and Jose Lado, assistant professor in the department of Applied Physics at Aalto.

The experimental team used atomic bricks to build walls capable of stopping the electrons. This was achieved by creating atomic walls that confined the electrons, leading to structures whose spectrum was then compared with theoretical predictions, demonstrating that electrons were confined. In particular, it was obtained that the engineered structures gave rise to nearly perfect confinement of electrons, as demonstrated from the emergence of sharp quantum well resonances with a remarkably long lifetime.

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Quantum computers have the potential to revolutionise the way we solve hard computing problems, from creating advanced artificial intelligence to simulating chemical reactions in order to create the next generation of materials or drugs. But actually building such machines is very difficult because they involve exotic components and have to be kept in highly controlled environments. And the ones we have so far can’t outperform traditional machines as yet.

But with a team of researchers from the UK and France, we have demonstrated that it may well be possible to build a quantum computer from conventional silicon-based electronic components. This could pave the way for large-scale manufacturing of quantum computers much sooner than might otherwise be possible.

The theoretical superior power of quantum computers derives from the laws of nanoscale or “quantum” physics. Unlike conventional computers, which store information in binary bits that can be either “0” or “1”, quantum computers use quantum bits (or qubits) that could be in a combination of “0” and “1” at the same time. This is because quantum physics allows particles to be in different states or places simultaneously.

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DNA replication is a process of critical importance to the cell, and must be coordinated precisely to ensure that genomic information is duplicated once and only once during each cell cycle. Using super-resolution technology a University of Technology Sydney led team has directly visualized the process of DNA replication in single human cells.

This is the first quantitative characterization to date of the spatio-temporal organization, morphology, and in situ epigenetic signatures of individual replication foci (RFi) in single human at the nanoscale.

The results of the study, published in PNAS (Proceedings of the National Academy of Sciences) give new insight into a poorly understood area of DNA replication namely how replication origin sites are chosen from thousands of possible sites.

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‘Twisted’ layers of 2D materials produce photonic topological transition at ‘magic’ rotation angles.

Monash researchers are part of an international collaboration applying ‘twistronics’ concepts (the science of layering and twisting 2D materials to control their electrical properties) to manipulate the flow of light in extreme ways.

The findings, published today in the journal Nature, hold the promise for leapfrog advances in a variety of light-driven technologies, including nano-imaging devices; high-speed, low-energy optical computers; and biosensors.

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A team of researchers affiliated with several institutions in the U.S. has conducted an analysis of the system-wide costs and benefits of using engineered nanomaterials (ENMs) on crop-based agriculture. In their paper published in the journal Nature Nanotechnology, the group describes their analysis and what they found.

As scientists have come to realize that vast improvements in agricultural practices are needed if future generations are going to be able to grow enough food to feed the expected rise in population. They have increasingly turned to technology-based solutions, rather than just looking for biological advances. One such approach involves the design and use of ENMs on crops as a means of improving pest control and fertilizer efficiency. Prior research has shown that some ENMs can be mixed into the soil as a form of pest control or as a means of diverting fertilizer directly to the roots, reducing the amount required. In a similar vein, some prior research has shown that ENMs can be applied to parts of the plant above-ground as a means of pest control. What has been less well studied, the researchers note, is the overall impact of ENMs on crops and the environment.

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To the general public, lasers heat objects. And generally, that would be correct.

But lasers also show promise to do quite the opposite — to cool materials. Lasers that can cool materials could revolutionize fields ranging from bio-imaging to quantum communication.

In 2015, University of Washington researchers announced that they can use a laser to cool water and other liquids below room temperature. Now that same team has used a similar approach to refrigerate something quite different: a solid semiconductor. As the team shows in a paper published today (June 23, 2020) in Nature Communications, they could use an infrared laser to cool the solid semiconductor by at least 20 degrees C, or 36 F, below room temperature.

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With a new nanoparticle that converts light to heat, a team of researchers has found a promising technology for clearing water of pollutants.

Trace amounts of contaminants such as pesticides, pharmaceuticals and perfluorooctanoic acid in drinking water sources have posed significant health risks to humans in recent years. These micropollutants have eluded conventional treatment processes, but certain chemical processes that typically involve ozone, hydrogen peroxide or UV light have proven effective. These processes, however, can be expensive and energy-intensive.

A new nanoparticle created by Yale University engineers as part of an effort for the Rice-based Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment (NEWT) could lead to technologies that get around those limitations. The particle is described in a study published this week in the Proceedings of the National Academy of Sciences.

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Rapid progress has been made in recent years to build these tiny machines, thanks to supramolecular chemists, chemical and biomolecular engineers, and nanotechnologists, among others, working closely together. But one area that still needs improvement is controlling the movements of swarms of molecular robots, so they can perform multiple tasks simultaneously.

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Researchers at Empa and EPFL have created one of the smallest motors ever made. It’s composed of just 16 atoms, and at that tiny size it seems to function right on the boundary between classical physics and the spooky quantum realm.

Like its macroscopic counterparts, this mini motor is made up of a moving part (the rotor) and a fixed part (the stator). The stator in this case is a cluster of six palladium atoms and six gallium atoms arranged in a rough triangular shape. Meanwhile, the rotor is a four-atom acetylene molecule, which rotates on the surface of the stator. The whole machine measures less than a nanometer wide.

The molecular motor can be powered by either thermal or electrical energy, although the latter was found to be much more useful. At room temperature, for example, the rotor was found to rotate back and forth at random. But when an electric current was applied using an electron scanning microscope, the rotor would spin in one direction with a 99-percent stability.

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