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Category: nanotechnology

Scientists at the University of Tsukuba use computer calculations to propose a new way to rearrange the carbon atoms in a diamond to make it even harder, which may be useful in industrial applications that rely on synthetic cutting diamonds.

Researchers at the University of Tsukuba used computer calculations to design a new carbon-based material even harder than diamond. This structure, dubbed “pentadiamond” by its creators, may be useful for replacing current synthetic diamonds in difficult cutting manufacturing tasks.

Diamonds, which are made entirely of carbon atoms arranged in a dense lattice, are famous for their unmatched hardness among known materials. However, carbon can form many other stable configurations, called allotropes. These include the familiar graphite in pencil lead, as well as nanomaterials such as carbon nanotubes. The mechanical properties, including hardness, of an allotrope depend mostly on the way its atoms bond with each other. In conventional diamonds, each carbon atom forms a covalent bond with four neighbors. Chemists call carbon atoms like this as having sp3 hybridization. In nanotubes and some other materials, each carbon forms three bonds, called sp2 hybridization.

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Bright, iridescent colors observed in nature are often caused by light interference within nanoscale periodic lattices, inspiring numerous strategies for coloration devoid of inorganic pigments. Here, we describe and characterize the septum of the Lunaria annua plant that generates large (multicentimeter), freestanding iridescent sheets, with distinctive silvery-white reflective appearance. This originates from the thin-film assembly of cellulose fibers in the cells of the septum that induce thin-film interference–like colors at the microscale, thus accounting for the structure’s overall silvery-white reflectance at the macroscale. These cells further assemble into two thin layers, resulting in a mechanically robust, iridescent septum, which is also significantly light due to its high air porosity (70%) arising from the cells’ hollow-core structure. This combination of hierarchical structure comprising mechanical and optical function can inspire technological classes of devices and interfaces based on robust, light, and spectrally responsive natural substrates.

Structural color has captured the fascination of optical researchers through numerous observations throughout history, both in naturally occurring structures and in the animal world (1–3). Plants have also evolved structural colors to fulfill a variety of functions (4–7): Structurally colored leaves (8–10), flowers (11, 12), and fruits (4, 5, 13, 14) are used by plants to regulate light harvesting (8, 15–17) and attract pollinators (6, 7), while they are also believed to promote seed dispersal (4, 5). The few, so far, described plants whose fruits are structurally colored are understory species living in tropical regions, whose fruits reflect light spanning from deep metallic blue to green when ripe.

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A team of researchers from the Technion – Israel Institute of Technology has observed branched flow of light for the very first time. The findings are published in Nature and are featured on the cover of the July 2, 2020 issue.

The study was carried out by Ph.D. student Anatoly (Tolik) Patsyk, in collaboration with Miguel A. Bandres, who was a postdoctoral fellow at Technion when the project started and is now an Assistant Professor at CREOL, College of Optics and Photonics, University of Central Florida. The research was led by Technion President Professor Uri Sivan and Distinguished Professor Mordechai (Moti) Segev of the Technion’s Physics and Electrical Engineering Faculties, the Solid State Institute, and the Russell Berrie Nanotechnology Institute.

When waves travel through landscapes that contain disturbances, they naturally scatter, often in all directions. Scattering of light is a , found in many places in nature. For example, scattering of light is the reason for the blue color of the sky. As it turns out, when the length over which disturbances vary is much larger than the wavelength, the wave scatters in an unusual fashion: it forms channels (branches) of enhanced intensity that continue to divide, or branch out, as the wave propagates. This phenomenon is known as branched flow. It was first observed in 2001 with electrons, and had been suggested to be ubiquitous and occur also for all waves in nature, for example sound waves and even ocean waves. Now, Technion researchers are bringing branched flow to the domain of light: they have made an experimental observation of branched flow of light.

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Research at IIT-Istituto Italiano di Tecnologia (Italian Institute of Technology) has led to the revolutionary development of an artificial liquid retinal prosthesis to counteract the effects of diseases such as retinitis pigmentosa and age-related macular degeneration that cause the progressive degeneration of photoreceptors of the retina, resulting in blindness. The study has been published in Nature Nanotechnology.

The study represents the state of the art in retinal prosthetics and is an evolution of the planar artificial retinal model developed by the same team in 2017 and based on organic semiconductor materials (Nature Materials 2017, 16: 681–689).

The ‘second generation’ artificial retina is biomimetic, offers and consists of an aqueous component in which photoactive polymeric nanoparticles (whose size is 350 nanometres, thus about 1/100 of the diameter of a hair) are suspended, and will replace damaged photoreceptors.

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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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