Category Technology/Electronics

Quick and easy coating process makes surfaces omniphobic. (© Wiley) Read more: Totally repellent – Quick and easy coating process makes surfaces omniphobic

Surfaces that repel all dirt and graffiti, are easy to clean, and cause liquids to bead up and slide off (like the frequently mentioned lotus blossom), are high on the wish lists of engineers and scientists. However, none of the technologies developed in the past has been a sweeping success. Scientists have now introduced a new method for making transparent, dirt-repellant coatings that can be applied very quickly and easily. The coatings repel both water and oily liquids and are stable at higher pressures and temperatures.

Prior approaches involved fluoropolymers (e.g. Teflon) and silicones...

Nearly 32X more sensitive than microphones of standard nickel-based construction, University of Belgrade researchers created a vibrating membrane – the part of a condenser microphone which converts the sound to a current, from graphene, with up to 15 dB higher sensitivity compared to a commercial microphone, at frequencies up to 11 kHz.

“We wanted to show that graphene, although a relatively new material, has potential for real world applications” explains Marko Spasenovic. “Given its light weight, high mechanical strength and flexibility, graphene just begs to be used as an acoustic membrane material.”

The graphene membrane, approximately 60 layers thick, was grown on a nickel foil using chemical vapour deposition, to ensure consistent quality across all the samples...

Schematic of a laser beam energizing a monolayer semiconductor made up of molybdenum disulfide (MoS2). The red glowing dots are particles excited by the laser. Credit: Der-Hsien Lien Read more at: http://phys.org/news/2015-11-defect-free-molecule-thick.html#jCp

An emerging class of atomically thin materials, monolayer semiconductors has generated a great deal of buzz in the world of materials science. Monolayers hold promise in the development of transparent LED displays, ultra-high efficiency solar cells, photo detectors and nanoscale transistors. Their downside? The films are notoriously riddled with defects, killing their performance.

But a UCLA, Berkeley, and Lawrence Berkeley National Lab team, has found a simple way to fix these defects via an organic superacid...

Left: Allowed states for the standard type-I Weyl fermion. When energy is tuned from below, at zero energy, a pinch in the number of allowed states guarantees the absence of many-body phenomena such as superconductivity or ordering. Right: The newly discovered type-II Weyl fermion. At zero energy, a large number of allowed states are still available. This allows for the presence of superconductivity, magnetism, and pair-density wave phenomena. Credit: B. Andrei Bernevig et al.

An international team of researchers has predicted the existence of a new type of particle called the type-II Weyl fermion in metallic materials. When subjected to a magnetic field, the materials act as insulators for current applied in some directions and as conductors for current applied in other directions...