Unique patterns made from tiny, randomly scattered silver nanowires have been created by a group of researchers from South Korea in an attempt to authenticate goods and tackle the growing problem of counterfeiting. The nanoscale ‘fingerprints’ are made by randomly dumping 20 to 30 individual nanowires, each with an average length of 10 to 50 µm, onto a thin plastic film, and could be used to tag a variety of goods from electronics and drugs to credit cards and bank notes. They have been presented in a recent paper published the journal Nanotechnology. According to the researchers, the fingerprints are almost impossible to replicate because of the natural randomness of their creation and the difficulty associated with manipulating such small materials.
From super-lubricants, to solar cells, to the fledgling technology of valleytronics, there is much to be excited about with the discovery of a unique new two-dimensional semiconductor, rhenium disulfide, by researchers at Berkeley Lab’s Molecular Foundry. Rhenium disulfide, unlike molybdenum disulfide and other dichalcogenides, behaves electronically as if it were a 2D monolayer even as a 3D bulk material. This not only opens the door to 2D electronic applications with a 3D material, it also makes it possible to study 2D physics with easy-to-make 3D crystals. Rhenium disulfide’s weak interlayer coupling should make this material highly useful in tribology and other low-friction applications. The new material should also be valuable for solar cell applications. It might also be a less expensive alternative to diamond for valleytronics.
Scientists at the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University have discovered a potential way to make graphene—a single layer of carbon atoms with great promise for future electronics—superconducting, a state in which it would carry electricity with 100 percent efficiency. Researchers used a beam of intense ultraviolet light to look deep into the electronic structure of a material made of alternating layers of graphene and calcium. While it’s been known for nearly a decade that this combined material is superconducting, the new study offers the first compelling evidence that the graphene layers are instrumental in this process, a discovery that could transform the engineering of materials for nanoscale electronic devices. The researchers saw how electrons scatter back and forth between graphene and calcium, interact with natural vibrations in the material’s atomic structure and pair up to conduct electricity without resistance. They reported their findings in Nature Communications.
Researchers from North Carolina State University have developed a new processing technique that makes light emitting diodes brighter and more resilient by coating the semiconductor material gallium nitride with a layer of phosphorus-derived acid. The researchers started with polar GaN, composed of alternating layers of gallium and nitrogen. To increase luminescence, they etched the surface of the material with phosphoric acid. At the same time, they added phosphonic groups – organic molecules containing phosphorus – that self-assembled into a monolayer on the surface of the material. This layer further increased luminescence and improved the stability of the GaN by making it less likely to react chemically with its environment. The paper, “In Situ Chemical Functionalization of Gallium Nitride with Phosphonic Acid Derivatives during Etching,” is published online in the journal Langmuir.
(Chemical & Engineering News) To supplement or even replace sutures, researchers have proposed applying sticky, biodegradable mats of polymer nanofibers onto surgical incisions to seal them and promote healing. But existing methods of depositing such mats aren’t compatible with living cells and tissues. Now, researchers have demonstrated that they can spray polymer nanofibers directly onto biological tissues using an airbrush from a hardware store. Mats of polymer nanofibers show potential not only for surgery but also as biodegradable, drug-releasing implants or as scaffolds for tissue engineering, says Peter Kofinas, a bioengineer at the University of Maryland, College Park. Current methods for making the mats—such as electrospinning, which involves electric current—would damage living cells if the mats were made in situ. To devise a way to create the mats directly on the tissue, Kofinas and colleagues adapted a commercial airbrush.