Showing Spotlights 1641 - 1648 of 2425 in category All (newest first):
A few days ago we ran a Nanowerk Spotlight on a nanostructuring technique that uses an extremely narrow electron beam to knock individual carbon atoms from carbon nanotubes with atomic precision, a technique that could potentially be used to change the properties of the nanotubes. In contrast to this deliberately created defect, researchers are concerned about unintentional defects created by electron beams during examination of carbon nanomaterials with transmission electron microscopes like a high-resolution transmission electron microscope (HRTEM). For a long time it has been thought that if the accelerating voltage of electrons could be reduced to 80 kV in an electron microscope, then the electrons would not possess sufficient energy to cause knock-on damage in carbon nanomaterials. Knock-on damage occurs when electrons are scattered by the nucleus of the atom they are probing. Upon scattering, energy is transferred. In some circumstances this energy can be large enough to dislodge the atom from its position. A British-German team has examined how electrons accelerated at 80 kV interact with singe-walled carbon nanotubes and shown that in some circumstances SWCNTs were unstable.
Jun 25th, 2009
Gas sensing applications are numerous in our modern society and include process monitoring, environmental compliance, health applications, homeland security, agriculture, etc. Gas sensors often operate by detecting the subtle changes that deposited gas molecules make in the way electricity moves through a surface layer. Thus, the more surface available, the more sensitive the sensor will be. Nanoscale materials are intriguing materials for next-generation nanotechnology gas sensors since their relative surface areas are so large. A problem with existing gas nanosensors is the cross-interference of other gas analytes. For instance, carbon nanotube based gas sensors for the prominent air pollutant nitrogen dioxide have shown strong interference of ethanol and ammonia gases to the NO2 response. Another cross-interference often is caused by humidity, i.e. the water vapor in the air. New research now demonstrates how the manufacturing of a nanosensor for ammonia gas can be tuned to eliminate the interference of water vapor. The trick lies in accurately controlling the synthesis of the sensing nanomaterial.
Jun 23rd, 2009
A broad spectrum of therapeutics or effector molecules that address several areas of medicine, from inflammation, to cancer, and regenerative medicine, are insoluble in water (they are soluble primarily in solvents generally regarded as unsuitable for injection). The water insolubility of these therapeutics limits the means by which those compounds can be administered to the body. Rapid strategies to package and disperse these drugs in biocompatible vehicles while also maintaining their potent activity can have major implications in advancing fundamental, translational, and commercial/scale-up aspects of accelerating their clinical impact. A new study now shows a way in which nanodiamonds can be applied towards enhancing water dispersion of otherwise poorly watersoluble therapeutics. It realizes a high throughout strategy to solubilize a broad range of water-insoluble drugs, which coupled with the innate biocompatibility of nanodiamonds, provides an important foundation towards a nanotechnology platform approach for advanced drug delivery.
Jun 22nd, 2009
One of the outstanding challenges in nanotechnology generally, and in the exploitation of so-called 'bottom-up' assembly of basic nanoscale building blocks such as nanowires, is the development of techniques for assembling large numbers of such nanostructures into more complex systems and precisely specified patterns in an accurate, deterministic manner. For instance, it is possible to build transistors, optical devices, and sensors with very specific properties using nanowires. Thus many useful applications of nanowires will depend on the ability to take these building blocks and organize them in some deterministic way in order to ultimately construct and interface with a nanowire-based system. New work demonstrates the basic capability for, and elucidates some of the guiding principles in, the use of dielectrophoretic behavior to direct the placement of large numbers of nanowires on complex, pre-patterned structures as might be required for integration of nanowires with, for example, silicon-based microelectronic circuitry. It shows that a high level of placement precision can be achieved by paying careful attention to the signal frequency as well as the macroscopic electrode architecture that is employed.
Jun 19th, 2009
The manifold properties of carbon nanotubes (as well as other carbon nanomaterials such as fullerenes and graphene) are related to the various ways the carbon atoms can be arranged to form the tube lattice. Studies have shown that atomic-scale defects in these lattices can strongly influence the electronic and mechanical properties of the nanotubes. The simplest defect type is a vacancy where an atom is missing from the lattice site. Such defects can also be seen as chemically active sites for tube side wall functionalization. Due to the difficulty of observing vacancies directly, it remained unclear under what conditions vacancies in nanotubes are stable or exist at all. Researchers have now demonstrated a technique that allows them to remove carbon atoms from carbon nanotubes with atomic precision and in a controlled way with an extremely focused electron beam.
Jun 18th, 2009
As nanotechnologies are increasingly becoming the focus of public interests and concerns, there is a risk that public opinion is shaped by either fearmongering or unrealistic expectations. Public engagement in policy making, i.e. having a say in decisions about technological developments that will affect people's lives significantly, should be based on objective information and facts. Public engagement is one of the processes that allows for increased social inclusion. Engagement seeks to achieve increased two-way information flow and knowledge exchange as well as increase overall technological literacy. Previously, we have reported about a German approach to embedding nanotechnology developments in society and covered the social aspects of nanotechnology in Europe. Today, we are showcasing an example from Down Under.
Jun 17th, 2009
From a risk and safety point of view it is impossible to draw any definite conclusions as far as today's nanomaterials are concerned. Although gaining steam, nanotoxicological research is still scarce; standards are just emerging; and scientific findings can be contradicting each other because the underlying assumptions and methodologies vary. One initiative that tried to shed light on this issue is a recently completed global review of completed and near completed environment, health and safety research on nanomaterials and nanotechnology. The resulting EMERGNANO report is a unique attempt to identify and assess worldwide progress in relation to nanotechnology risk issues. The review doesn't provide any new data or conclusions but is offeres a fairly comprehensiv identification, stocktaking and analysis of of research carried out worldwide on nanotechnology safety, including that relating to hazard, exposure, risk assessment and regulation.
Jun 16th, 2009
Reciprocating devices are a common part of the macroscopic world. Examples of reciprocating machines are petrol and diesel engines or a hydraulic pump. At the core of these machines is a piston and cylinder assembly where the piston executes a reciprocating motion inside the cylinder. Reciprocating motion like that in a piston has not been available in a nanoscale machine until now. Ned Seeman and his team at New York University have designed a DNA device that exhibits reciprocal motion. They have used the PX-JX2 device, a robust sequence-dependent nanomechanical DNA machine, as the basis for constructing a pair of reciprocal devices, wherein one device assumes one state, while the other device assumes the opposite state.
Jun 11th, 2009