Showing Spotlights 1057 - 1064 of 2140 in category (newest first):
Brain-computer interfaces, neural probes, brain implants - they all require intensive in vivo studies on how to best combine inorganic electronics with organic neurons. Currently, most neural culture studies suffer from the fact that their cells migrate on a flat surface and are directly exposed to the culture solution, which do not reflect the microenvironment in vivo - neurons, though, can alter their behaviors dramatically in response to the environment change. Ideal cultures, therefore, should mimic the native neural microenvironment to capture the normal cell behavior. This has motivated a group of researchers to come up with this a semiconductor nanomembrane tube approach, which provides a 3D confinement that can potentially isolate the cells from the culture solution. Since these tubes are made from a semiconductor material, it means that they can be integrated with electronic functionalities such as voltage sensors.
Mar 31st, 2011
Regenerative medicine, in particular the area of tissue regeneration, is seeing a rapidly growing field of novel biomaterials that can act as bioactive scaffolds that induce tissue regeneration; that is in contrast to the more traditional concept of passively accepted implant materials. In order to present biological stimuli to the physiological environment and trigger tissue repair, optimal integration of synthetic biomaterials within the surrounding tissue is of paramount importance. In that respect, hydrogels made from biodegradable polymers are ideal candidates since they are generally biocompatible, biodegradable, and, in some cases, injectable. New research has provided firm evidence for a feasible bottom-up approach for the preparation of injectable gels by employing oppositely charged gelatin nanospheres as building blocks.
Mar 30th, 2011
The power conversion efficiency of solar cells made of conjugated polymer/nanorod nanocomposites can be maximized when the nanocomposites are aligned perpendicularly between two electrodes for effective exciton dissociation and transport. To realize this, external fields can be applied to induce the self-assembly/alignment. The challenge is how to assemble them over a large scale - current self-assembly studies of cadmium selenide nanorods in literature are limited to only a micrometer scale. New design approaches are therefore needed to solve this problem. Due to their intrinsic structural anisotropy, nanorods possess many unique properties that make them potentially better nanocrystals than quantum dots for photovoltaics and biomedical applications.
Mar 29th, 2011
The complex processes inside living systems emerge from the interactions of countless molecules. Understanding these interactions at the single molecule level is of great importance because mechanisms governing their function can be revealed best by interrogating individual molecules. Scientists rely on single-molecule techniques that allow them to isolate individual molecules and sequentially transport them for measurement and, potentially, manipulation. Most commonly, molecules are interfaced with tools like optical tweezers and atomic force microscopes. These devices are precision force sensors. Many interactions among biological molecules are short lived. Their lifetimes can be as short as a nanosecond. The existing single molecule techniques are limited in their temporal resolution, probing the timescales on the order of several milliseconds to a second. In new work, researchers have extended the reach of single molecule experiments to the microsecond timescale.
Mar 28th, 2011
There are already several technologies that potentially allow mass production of graphene sheets; several of them are processing graphene in solution by exfoliating graphite. The general problem with this approach is however that is has been so far impossible to regenerate the undisturbed graphene lattice which was present prior to oxidation as decarboxylation inevitable takes place in the reduction step. In new work, researchers have now demonstrated the first bulk wet chemical exfoliation of graphite in association with an in situ covalent functionalization of intermediately generated graphene. With this novel chemical method, it is now possible to achieve covalently bonded functionalities without mechanical or sonochemical treatment. The covalent functionalization also protects the single-layer graphene from reaggregation and substrate-induced doping.
Mar 25th, 2011
In the decades-old quest to build artificial muscles, many materials have been investigated with regard to their suitability for actuator application (the ability of a material to reversibly change dimensions under the influence of various stimuli). Recently, hope in obtaining improved artificial muscles was revitalized by the discovery of the extraordinary mechanical and electrical properties of graphene and its chemical derivatives. A new study shows that electrical heating of graphene oxide nanoribbons mats results in reversible generation of 1.6% stress and maximum work capacity of about 40 J/kg, which is similar to that of natural muscle. Unlike previous studies, the team obtained the graphene material by chemical unzipping of multi-walled carbon nanotubes.
Mar 24th, 2011
Photonic crystals are used to guide and localize light for all-optical processing of signals/information; to engineer dispersion and slow light; to harvest light (collect and redirect); and thresholdless lasing, that can be engineered by setting spectral ranges where light can be emitted. so far, there have been no demonstrations of full photonic bandgap at visible wavelengths - i.e., that at a certain visible range (between 400 nm to 780 nm) determined by the 3D photonic crystal structure, the light is rejected (reflected) at all angles of incidence. Researchers have now used a 3D nano-sculpturing process to fabricate 3D photonic crystal. The great potential of these 3D photonic crystal lies in the possibility to control light on a sub-wavelength scale.
Mar 23rd, 2011
The commercial realization of carbon nanotube-based electronic devices and their integration into the existing silicon-based processor technologies is still hampered by the inability to scale up the - currently lab-based - fabrication processes to manufacture a large number of devices on a single chip. The fundamental issue of carbon nanotube device fabrication still remains the biggest challenge for effective commercialization of nanotube electronics. In a further step towards large-scale integration of single-walled carbon nanotubes (SWCNTs) into complex functional electronic circuits, researchers have now combined a previously developed dielectrophoretic deposition approach with SWCNT sorting using density gradient ultracentrifugation, ensuring high purity of SWCNTs in suspension and consequently in the assembled devices.
Mar 22nd, 2011