Epitaxy on nanopatterned graphene enables the realization of a broad spectrum of freestanding single-crystalline membranes with substantially reduced defects.
Category: nanotechnology – Page 128
Skoltech scientists modeled the behavior of nanobubbles appearing in van der Waals heterostructures and the behavior of substances trapped inside the bubbles. In the future, the new model will help obtain equations of state for substances in nano-volumes, opening up new opportunities for the extraction of hydrocarbons from rock with large amounts of micro-and nanopores. The results of the study were published in the Journal of Chemical Physics.
The van der Waals nanostructures hold much promise for the study of tiniest samples with volumes from 1 cubic micron down to several cubic nanometers. These atomically thin layers of two-dimensional materials, such as graphene, hexagonal boron nitride (hBN) and dichalcogenides of transition metals, are held together by weak van der Waals interaction only. Inserting a sample between the layers separates the upper and bottom layers, making the upper layer lift to form a nanobubble. The resulting structure will then become available for transmission electron and atomic force microscopy, providing an insight into the structure of the substance inside the bubble.
The properties exhibited by substances inside the van der Waals nanobubbles are quite unusual. For example, water trapped inside a nanobubble displays a tenfold decrease in its dielectric constant and etches the diamond surface, something it would never do under normal conditions. Argon which typically exists in liquid form when in large quantities can become solid at the same pressure if trapped inside very small nanobubbles with a radius of less than 50 nanometers.
By helping scientists control a strange but useful phenomenon of quantum mechanics, an ultrathin invention could make future computing, sensing, and encryption technologies remarkably smaller and more powerful. The device is described in new research that was recently published in the journal Science.
This device could replace a roomful of equipment to link photons in a bizarre quantum effect called entanglement, according to scientists at Sandia National Laboratories and the Max Planck Institute for the Science of Light. It is a kind of nano-engineered material called a metasurface and paves the way for entangling photons in complex ways that have not been possible with compact technologies.
When photons are said to be entangled, it means they are linked in such a way that actions on one affect the other, no matter where or how far apart the photons are in the universe. It is a spooky effect of quantum mechanics, the laws of physics that govern particles and other very tiny things.
Molecules of the rare metallic element niobium can be used as molecular building blocks to design electrochemical energy storage materials. Mark Rambaran, Department of Chemistry at Umeå University, presents in his thesis a method for producing solid materials from aqueous solutions containing nano-sized niobium molecules, called polyoxoniobates.
“These polyoxoniobates are water-soluble and can be synthesized in large volumes. They act as molecular building blocks, in the same way as when a child stacks Lego bricks,” Mark Rambaran says. “They can be used to make a wide range of materials, including supercapacitors that facilitate lithium-ion storage.”
Synthesis of polyoxoniobates can be done with microwave irradiation, because it is a rapid and efficient alternative to conventional hydrothermal methods, Mark Rambaran shows in his thesis.
When the inside of a mollusk shell shimmers in sunlight, the iridescence isn’t produced by colored pigments but by tiny physical structures self-assembled from living cells and inorganic components. Now, a team of researchers at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) has developed a platform to mimic this self-assembly ability by engineering living cells to act as a starting point for building composite materials.
Engineered living materials (ELMs) use living cells as “materials scaffolds” and are a new class of material that might open the door to self-healing materials and other advanced applications in bioelectronics, biosensing, and smart materials. Such materials could mimic emergent properties found in nature—where a complex system has properties that the individual components do not have—such as iridescence or strength.
Borrowing from this complexity seen in nature, the Berkeley Lab researchers engineered a bacterium that can attach a wide range of nanomaterials to its cell surface. They can also precisely control the makeup and how densely packed the components are, creating a stable hybrid living material. The study describing their work was recently published in ACS Synthetic Biology.
In nature, wood, shells, and other structural materials are lightweight, strong, and tough. Significantly, these materials are made at the ambient temperature in the local environment – not at the high temperatures at which human-made structural materials are generally processed. Similar materials are difficult to make synthetically. In a review article in Nature Materials, a team of scientists assessed the common design motifs of a range of natural structural materials and determined what it would take to design and fabricate structures that mimic nature. They considered the remaining challenges to include the need for comprehensive characterization of strength and toughness to identify underlying multiscale mechanisms.
This comprehensive assessment provides new inspiration and understanding of design principles that may lead to more efficient synthetic approaches for advanced, lightweight structural materials for transportation, buildings, batteries, and energy conversion.
In the natural world, many of the structural materials (wood, shells, bones, etc.) are hybrid materials made up of simple constituents that are assembled at ambient temperatures and often have remarkable properties. Even though the constituent materials generally have poor intrinsic properties, the superior extrinsic properties of the hybrid materials are the result of the arrangement of hard and soft phases in complex hierarchical architectures, with dimensions spanning from the nanoscale to the macroscale. The resulting materials are lightweight and usually show interesting combinations of strength and toughness, even though these two key structural properties tend to be mutually exclusive. It is relatively easy to make materials that are strong or tough, but difficult to make materials that are both.
New research inspired by ice giants like Neptune and Uranus shows lasers can transform a common plastic into tiny diamonds.
Ralph C. Merkle is a computer scientist. He is one of the inventors of public key cryptography, the inventor of cryptographic hashing, and more recently a researcher and speaker of cryonics.
Videos in the talk: David Eagleman https://www.youtube.com/watch?v=-5tZtYns6kE molecular nanotechnology: https://www.youtube.com/watch?v=zqyZ9bFl_qg.
Filmed 2017/04/30
Researchers investigated the polarization-dependence of the force exerted by circularly polarized light (CPL) by performing optical trapping of chiral nanoparticles. They found that left-and right-handed CPL exerted different strengths of the optical gradient force on the nanoparticles, and the D-and L-form particles are subject to different gradient force by CPL. The present results suggest that separation of materials according to their handedness of chirality can be realized by the optical force.
Chirality is the property that the structure is not superimposable on its mirrored image. Chiral materials exhibit the characteristic feature that they respond differently to left-and right-circularly polarized light. When matter is irradiated with strong laser light, optical force is exerted on it. It has been expected theoretically that the optical force exerted on chiral materials by left-and right-circularly polarized light would also be different.
The research group at Institute for Molecular Science and three other universities used an experimental technique of optical trapping to observe the circular-polarization dependent optical gradient force exerted on chiral gold nanoparticles. Chiral gold nanoparticles have either D-form (right-handed) or L-form (left-handed) structure, and the experiment was performed using both.
Engineers at EPFL have found a way to insert carbon nanotubes into photosynthetic bacteria, which greatly improves their electrical output. They even pass these nanotubes down to their offspring when they divide, through what the team calls “inherited nanobionics.”
Solar cells are the leading source of renewable energy, but their production has a large environmental footprint. As with many things, we can take cues from nature about how to improve our own devices, and in this case photosynthetic bacteria, which get their energy from sunlight, could be used in microbial fuel cells.
In the new study, the EPFL team gave these bacteria a boost by inserting carbon nanotubes – tiny rolled-up sheets of graphene, a material that’s famously conductive. The nanotube-loaded bugs were able to produce up to 15 times more electricity than their non-edited counterparts from the same amount of sunlight.