Showing Spotlights 441 - 448 of 489 in category Fabrication Technologies and Devices (newest first):
Controlling the shape of nanostructures is one of the challenging issues presently faced by synthetic chemists and materials engineers. Various shapes of nanomaterials, such as sphere-, rod-, wire-, triangle-, cube-, and tube-outlines have been synthesized by various approaches. However, to produce nanostructures with high monodispersity is still one of the major issues to be solved. Most work in this area focused on inorganic or synthetically organic materials. Using pure biomolecules to produce nano- or micro-structures, without the assistance of inorganic materials, is rare. Biocompatible nanospheres have been and remain of intense interest for biosensor, drug delivery, and biomedical contrast imaging. A new research report coming out of China now shows that highly monodispersed nanospheres of cystine (a sulfur-containing amino acid) aggregate were successfully produced by a quite simple method without the assistance of any other inorganic materials. This work could be of great significance in the production of nanomaterials, biosensors, and drug delivery.
Oct 17th, 2006
Because of the huge effective surface area, the ability to blend different types of polymers, and the fact that the process is conducted at room temperature so that biological compounds can be loaded into the fibers, electrospinning has enormous potential to create new families of higher performance products across a wide array of industry sectors. For a technique invented in 1934, we are just now beginning to see its true potential.
Oct 5th, 2006
Seashells are natural armor materials. The need for toughness arises because aquatic organisms are subject to fluctuating forces and impacts during motion or through interaction with a moving environment. Nacre (mother-of-pearl), the pearly internal layer of many mollusc shells, is the best example of a natural armor material that exhibits structural robustness, despite the brittle nature of their ceramic constituents. This material is composed of about 95% inorganic aragonite with only a few percent of organic biopolymer by volume. New research at the university of South Carolina reveals the toughening secrets in nacre: rotation and deformation of aragonite nanograins absorb energy in the deformation of nacre. The aragonite nanograins in nacre are not brittle but deformable. The new findings may lead to the development of ultra-tough nanocomposites, for instance for armor material, by realizing the rotation mechanism.
Oct 2nd, 2006
Individual carbon nanotubes (CNTs) of different structural and thus electronic characteristics can be joined to build up three-terminal logic devices. However, today this can only be achieved using highly sophisticated nanomanipulation processes. The direct growth of intrinsic functional CNT elements such as Y-shaped CNTS (YCNTs) and helical CNTs (HCNTs) can be considered as an important alternative. YCNTs already have proven to show rapid and nonlinear transistor action without the need for external gating, while HCNTs could be used as inductive elements offering rapid signal processing. Additionally, HCNTs have shown operational functionality as high sensitivity force and mass sensors and are of great interest for nanoelectromechanical systems (NEMS). A research group in Spain now reports that sulfur may be used as a highly efficient additive in chemical vapor deposition (CVD) processes, allowing enhanced selectivity in the synthesis of helical and Y-shaped CNTs.
Sep 29th, 2006
Imagine to catch one, or a few, molecules dissolved in water, lock them up in a cage with a diameter of a few hundred nanometers, and keep them locked for a given length of time. Then bring these containers with the "captive" molecules to places within the solution where you want to have them, and release the captured molecules from their captivity on chemical command. Or simply keep the molecules in the cage "prison" locked up, add a few more different molecules to water, and watch their chemical reaction following movement across the container wall in "solitary" confinement within the containers with the molecules already captured. Such dreams of nanotechnologists have come much closer to reality as a result of a discovery made by a team of researchers, lead by Professor Julius Vancso of the University of Twente, from the MESA+ Institute for Nanotechnology collaborating with scientists of the Max Planck Institute of Colloids and Interfaces in Golm, Germany.
Sep 28th, 2006
With a better understanding of how fullerenes and nanotubes form, scientists and material engineers would be in a better position to provide conditions more favorable for the formation of a particular fullerene or a particular chirality and length nanotube. Researchers have used a number of computational and theoretical tools to explain the experimental observations and develop a picture of the dynamics for fullerene growth, yet no universally agreed model exists for the fullerene growth. To understand the phenomenon of fullerene growth during its synthesis, researchers modeled a minimum energy growth route using a semi-empirical quantum mechanics code. C2 addition leading to C60 was modeled and three main routes, i.e. cyclic ring growth, pentagon and fullerene road, were studied.
Sep 19th, 2006
New research coming out of France opens the route for the processing of numerous multifunctional materials with specific properties. So far, the design of new multifunctional devices based on the combination of different materials has been a real challenge in materials science. One way to develop multifunctional materials is the design of a surface at the nanometer scale. However, modifying the surface of materials by organizing nanoparticles of controlled size, morphology and amount of coverage into a uniform shell has proven to be a considerable hurdle. Numerous approaches are being developed for the synthesis of these materials using organic or inorganic coatings. French researchers used a coating process called supercritical fluid chemical deposition for nanomaterial surface design.
Sep 15th, 2006
The use of design concepts adapted from nature is a promising new route to the development of advanced materials, with biominerals providing an ample source of examples. For instance, Nature's ability to manipulate poor engineering materials such as calcium carbonate to produce skeletal materials with considerable fracture resistance is an ideal inspiration for this approach. Researchers in the UK now report a simple and general approach to single crystal growth, employing structured films of generic polymers to direct the growth of single crystals. By using straightforward patterning techniques they are able to access a large variety of patterns with a continuous range of length scales from the macroscopic to the nanometer level.
Sep 12th, 2006