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Study co-led by Berkeley Lab reveals how wavelike plasmons could power up a new class of sensing and photochemical technologies at the nanoscale.

Wavelike, collective oscillations of electrons known as “plasmons” are very important for determining the optical and electronic properties of metals.

In atomically thin 2D materials, plasmons have an energy that is more useful for applications, including sensors and communication devices, than plasmons found in bulk metals. But determining how long plasmons live and whether their energy and other properties can be controlled at the nanoscale (billionths of a meter) has eluded many.

Circa 2016

Not all important scientific research is cool looking, or has a cool name. But now and then you get something with both. These self-assembling carbon nanotubes are created with a process called Teslaphoresis. If you’ve read a more impressive-sounding sentence today, I’d like to hear it.

Even the lab of Rice University chemist Paul Cherukuri looks like a proper mad scientist’s lair. But don’t let the flashy trappings fool you: this is a very significant development.

Continue reading “Teslaphoresis-activated self-assembling carbon nanotubes look even cooler than they sound” »

Anyons – the particle-like collective excitations that can exist in some 2D materials – tend to bunch together in a two-dimensional conductor. This behaviour, which has now been observed by physicists at the Laboratory of Physics of the ENS (LPENS) and the Center for Nanoscience and Nanotechnologies (C2N) in Paris, France, is completely different to that of electrons, and experimental evidence for it is important both for fundamental physics and for the potential future development of devices based on these exotic quasiparticles.

The everyday three-dimensional world contains two types of elementary particles: fermions and bosons. Fermions, such as electrons, obey the Pauli exclusion principle, meaning that no two fermions can ever occupy the same quantum state. This tendency to flee from each other is at the heart of a wide range of phenomena, including the electronic structure of atoms, the stability of neutron stars and the difference between metals (which conduct electric current) and insulators (which don’t). Bosons such as photons, on the other hand, tend to bunch together – a gregarious behaviour that gives rise to superfluid and superconducting behaviours when many bosons exist in the same quantum state.

Within the framework of quantum mechanics, fermions also differ from bosons in that they have antisymmetric wavefunctions – meaning that a minus sign (that is, a phase φ equal to π) is introduced whenever two fermions are exchanged. Bosons, in contrast, have symmetric wavefunctions that remain the same when two bosons are exchanged (φ=0).

Prof. Dong Sung Kim and his joint research team presented a new technology that can increase the amount of power generated by a triboelectric nanogenerator. The research team developed a high-efficiency integrated circuit to obtain reliable and practical electrical energy from the triboelectric nanogenerator.

Nanoparticle superlattice films that form at the solid-liquid interface are important for mesoscale materials but are challenging to analyze on the onset of formation at a solid-liquid interface. In a new report on Science Advances, E. Cepeda-Perez and a research team in materials, physics and chemistry in Germany studied the early stages of nanoparticle assembly at solid-liquid interfaces using liquid-phase electron microscopy. They observed oleylamine-stabilized gold nanoparticles to spontaneously form thin layers on a silicon nitride membrane window of the liquid enclosure. In the first monolayer, the assembly maintained dense packings of hexagonal symmetry independent of the nonpolar solvent type. The second layer displayed geometries ranging from dense packing in a hexagonal honeycomb structure to quasi-crystalline particle arrangements—based on the dielectric constant of the liquid. The complex structures made of weaker interactions remained preserved, while the surface remained immersed in liquid. By fine-tuning the properties of materials involved in nanoparticle superlattice formation, Cepeda-Perez et al. controlled the three-dimensional (3D) geometry of a superlattice, including quasi-crystals (a new state of matter).

Nanoparticles that are densely packed into two or three dimensions can form regular arrays of nanoparticle superlattices. For example, semiconductor particle superlattices can act as “meta” semiconductors when doped with particles to form new mesoscale materials, while plasmonic particles in dense superlattices can couple to form collective modes with angle-dependent and tunable wavelength responses. Large electric fields can occur between such particles for surface-enhanced Raman spectroscopy. Superlattices can be developed at liquid-liquid, gas-liquid and solid-liquid interfaces, where static and dynamic interactions between particle-substrate, particle-particle and particle-liquid interactions can dictate the structure of superlattices. However, it remains difficult to predict such structures in advance. For example, simulating the assembly of superlattices at multiple stages is not yet possible, with very little in-lab real-space data available for modeling.

Just as a literature buff might explore a novel for recurring themes, physicists and mathematicians search for repeating structures present throughout nature.

For example, a certain geometrical structure of knots, which scientists call a Hopfion, manifests itself in unexpected corners of the universe, ranging from particle physics, to biology, to cosmology. Like the Fibonacci spiral and the golden ratio, the Hopfion pattern unites different scientific fields, and deeper understanding of its structure and influence will help scientists to develop transformative technologies.

Continue reading “Novel insight reveals topological tangle in unexpected corner of the universe” »

Meticulously organised fatty acids are responsible for the bacteria-killing, superhydrophobic nanostructures on cicada wings. The team behind the discovery hopes that its work will inspire antimicrobial surfaces that mimic cicada wings for use in settings such as hospitals.

When in contact with dust, pollen and – importantly – water, the cicadas’ superhydrophobic wings repel matter to self-clean. These extraordinary properties are down to fatty acid nanopillars, periodically spaced and of nearly uniform height, that cover the wings.

Past work has generally only described cicadas’ wings as ‘waxy’ and not explained how these fatty acids nanopillars give rise to unique traits. Nor is it known exactly why cicada wings evolved antibacterial nanostructures. These gaps in our knowledge exist, in part, because of how diverse the cicada family is. But Marianne Alleyne’s group at the University of Illinois, Urbana–Champaign, along with colleagues at Sandia National Labs, set out to understand what role chemistry plays in the wings of two evolutionarily divergent species.

Circa 2019 o.o

There are enormous methods such as physical, chemical, and biological, for the synthesis of metallic nanoparticles (MNPs), which has become a matter of focus among material scientists. Green chemistry-based MNP synthesis is an area, which has gained much importance presently due to their non-toxicity and monodispersed nanoparticle preparation methodologies. Among green synthesis methods, plants are considered as efficient candidates for nanoparticle synthesis. The meticulous formation of different sizes and shapes of the nanoparticles using plants has spurred encouraging interest. The rate kinetics and stability of nanoparticle synthesis are well studied as well as appreciated in the arena of materials. Their capability to sequester metal ions and fastidiously define the dimensions using a plethora of capping proteins such as glutathione and phytochelatins is intriguing giving it a monodispersed size. This review is a comprehensive understanding of the metal nanoparticles synthesized by plants and apprehends the mechanism of nanoparticle synthesis exhaustively.

The startup claims to be “the world’s top supplier of graphene” and plans to release a non-flammable, environmentally friendly lithium battery that can charge “18 times faster than anything that is currently available on the market” — within the next year.