Browsing all articles in Publications
Mar
9

Chemically driven thermopower waves

nanotube conducting heatA team of scientists at MIT have discovered a previously unknown phenomenon that can cause powerful waves of energy to shoot through minuscule wires known as carbon nanotubes. The discovery could lead to a new way of producing electricity, the researchers say.

The phenomenon, described as thermopower waves, “opens up a new area of energy research, which is rare,” says Michael Strano, who was the senior author of a paper describing the new findings that appeared in Nature Materials. The lead author was Wonjoon Choi, a doctoral student in mechanical engineering.

A carbon nanotube (shown in the illustration made by Christine Daniloff) can produce a very rapid wave of power when it is coated by a layer of fuel and ignited, so that heat travels along the tube. Like a collection of flotsam propelled along the surface by waves travelling across the ocean, it turns out that a thermal wave — a moving pulse of heat — travelling along a microscopic wire can drive electrons along, creating an electrical current.

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Mar
8

Physicists find a way to see through opaque materials

Materials such as paper, paint, and biological tissue are opaque because the light that passes through them is scattered in complicated and seemingly random ways. A new experiment conducted by researchers at the City of Paris Industrial Physics and Chemistry Higher Educational Institution (ESPCI ParisTech) has shown that it’s possible to focus light through opaque materials and detect objects hidden behind them, provided you know enough about the material. The experiment is reported in Physical Review Letters.

seeing_through_opaque_materials

Knowing enough about the way light is scattered through materials would allow physicists to see through opaque substances, such as the sugar cube on the right. In addition, physicists could use information characterizing an opaque material to put it to work as a high quality optical component, comparable to the glass lens shown on the left.

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Mar
5

Iron-Clad Fibers: A Metal-Based Biological Strategy for Hard Flexible Coatings

Researchers at the Max Planck Institute of Colloids and Interfaces and collaborators at the University of California at Santa Barbara and the University of Chicago believe they have uncovered the basis how marine mussels use the byssus, a bundle of tough and extensible fibres, to fasten securely to wave-swept rocky coastlines.

mussel_fibres

(I) Mussels attach to hard surfaces in the marine intertidal zone with the byssus. (II) Byssal threads are extensible fibers with a hard and rough-textured protective cuticle (scanning electron microscopy). The knobby morphology of the cuticle originates from granular inclusions embedded in a continuous matrix. (III) The amount of dopa-iron complexes was found to be much higher in the granules than the matrix, which likely leads to their differences in mechanical performance during stretching. (Image: Matt Harrington, Max Planck Institute of Colloids and Interfaces)

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Mar
3

A novel graphene hybrid

graphene hybridRice University researchers have found a way to stitch graphene and hexagonal boron nitride (h-BN) into a two-dimensional quilt that offers new paths of exploration for materials scientists. The technique has implications for application of graphene materials in microelectronics that scale well below the limitations of silicon determined by Moore’s Law. New research demonstrates a way to achieve fine control in the creation of such hybrid, 2-D structures.

Layers of h-BN a single atom thick have the same lattice structure as graphene, but electrically the materials are at opposite ends of the spectrum: h-BN is an insulator, whereas graphene, the single-atom-layer form of carbon, is highly conductive. The ability to assemble them into a single lattice could lead to a rich variety of 2-D structures with electric properties ranging from metallic conductor to semiconductor to insulator.

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Mar
3

Smart capsules for water treatment with recyclable carbon nanotube cores

TEM image of the CNT core-in-hematite shell structures. (Image: Dr. Choi, KBSI)

TEM image of the CNT core-in-hematite shell structures. (Image: Dr. Choi, KBSI)

Numerous nanomaterials are in various stages of research and development, each possessing unique functionalities that are potentially applicable to the remediation of industrial wastewater, groundwater, surface water and drinking water. The main goal for most of this research is to develop low-cost and environmentally friendly materials for removal of heavy metals from water.

Drinking or ground water could be contaminated by heavy metal ions such as lead, chromium, and arsen discarded from industrial waste water. These heavy metal ions are regarded as highly toxic pollutants which could cause a wide range of health problem in case of a long-term accumulation in the body.

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Feb
25

Piezoelectric ribbons printed onto rubber

piezoelectric ribbons on rubberThe development of a method for integrating highly efficient energy conversion materials onto stretchable, biocompatible rubbers could yield breakthroughs in implantable or wearable energy harvesting systems. Being electromechanically coupled, piezoelectric crystals represent a particularly interesting subset of smart materials that function as sensors/actuators, bioMEMS devices, and energy converters. Yet, the crystallization of these materials generally requires high temperatures for maximally efficient performance, rendering them incompatible with temperature-sensitive plastics and rubbers.

Scientists from the Princeton University and the California Institute of Technology have found a way to overcome these limitations by presenting a scalable and parallel process for transferring crystalline piezoelectric nanothick ribbons of lead zirconate titanate (PZT) from host substrates onto flexible rubbers over macroscopic areas. Fundamental characterization of the ribbons by piezo-force microscopy indicates that their electromechanical energy conversion metrics are among the highest reported on a flexible medium.

Source: original article

Feb
23

Silicon-coated Nanonets to build better batteries

nanonetA tiny scaffold-like titanium structure of Nanonets coated with silicon particles could pave the way for faster, lighter and longer-lasting Lithium-ion batteries, according to a team of Boston College chemists who developed the new anode material using nanotechnology.

The web-like Nanonets developed in the lab of Boston College Assistant Professor of Chemistry Dunwei Wang offer a unique structural strength, more surface area and greater conductivity, which produced a charge/re-charge rate five to 10 times greater than typical Lithium-ion anode material, a common component in batteries for a range of consumer electronics, according to findings published in the American Chemical Society journal Nano Letters.

In addition, the Nanonets proved exceptionally durable, showing a negligible drop-off in capacity during charge and re-charge cycles. The researchers observed an average of 0.1% capacity fade per cycle between the 20th and the 100th cycles.

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Feb
16

Nanotech Discovery May Green Chemical Manufacturing

Nanotech catalystA new nanotech catalyst developed by McGill University Chemists Chao-Jun Li, Audrey Moores and their colleagues offers industry an opportunity to reduce the use of expensive and toxic heavy metals. Catalysts are substances used to facilitate and drive chemical reactions. Although chemists have long been aware of the ecological and economic impact of traditional chemical catalysts and do attempt to reuse their materials, it is generally difficult to separate the catalyzing chemicals from the finished product. The team’s discovery does away with this chemical process altogether.

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Jan
27

A force that guides the electrons is revealed

A team of researchers led by Professor Louis Taillefer from Université de Sherbrooke, has solved a 10 years long mystery on the behavior of electrons in superconducting materials at high temperatures. In the pseudogap phase, electrons are orientated spontaneously in a preferred direction. This fundamental discovery, published in the Nature journal, removes a major obstacle to the development of superconducting materials.

Superconductors are materials that conduct electricity without resistance. They are extremely promising in terms of technology, particularly for the transport of energy, maglev trains, magnetic medical imaging, wireless communications, quantum computing and many other applications.

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