Showing Spotlights 1673 - 1680 of 2382 in category All (newest first):
Scintillation - a flash of light, lasting only nanoseconds to microseconds, produced in a particular material when it absorbs ionizing radiation - is one of the main methods used for the detection of ionizing radiation. Scintillators are very versatile and can be used for detecting almost all types of radiation in a wide range of energy from several electron volts (eV) to tens of billion of electron volts (GeV). Scintillation is useful for sensing alpha, beta and gamma radiation as well as other nuclear particles and in some cases determining the particle type. For example, organic scintillators can sense fast neutrons emitted spontaneously from fissile isotopes of uranium and plutonium, enabling passive detection of nuclear weapons. The detection and identification of subatomic particles is not only important for nuclear nonproliferation efforts but is a wide-ranging scientific problem with implications for medical devices, radiography, biochemical analysis, particle physics, and even astrophysics. Scientists from the Sandia National Laboratories in California have now proposed that metal-organic frameworks (MOFs) could potentially offer the desired level of structural control, leading to an entirely new class of radiation detection materials.
Jan 14th, 2009
Conventional vaccine development is based on the body's successful approach to dealing with viral infections. Unfortunately, standard vaccine technologies are ineffective against some of the most devastating infectious diseases such as HIV. A key role in developing cell-mediated immunity against viruses is played by so-called T-cells, which belong to a group of white blood cells known as lymphocytes. One variant of T-cells (cytotoxic T lymphocytes) directly attacks body cells that are infected with a virus or malignant or abnormal tumor cells. These 'killer' T-cells are called into action by 'helper' T-cells, which also activate other immune cells to produce antibodies. HIV, though, takes over helper T-cells and uses them to replicate itself. A major focus in AIDS research has therefore been the development of a 'T-cell vaccine' that induces T-cell immunity. While it was shown that peptides in blood could effectively stimulate T cell immunity in monkeys, and peptides are considered safe vaccine antigens, proteases in vivo can rapidly degrade peptide-based vaccines and this has limited their utility to date. New research by scientists in Australia represents an important finding for vaccine delivery as it demonstrates a feasible method for protecting biologically active peptides for delivery to antigen presenting cells (APCs).
Jan 13th, 2009
Civilization as we know it would, literally, fall apart without techniques to join materials together. With its historic development tracing back to the Bronze Age, welding has been one of the key technologies that serves modern industry in broad areas such as construction, manufacturing, and engineering. As we have reported in a previous Nanotechnology Spotlight, this Bronze Age technique could prove very useful in building complex nanostructures. Researchers at the University of Sheffield in the UK have now demonstrated the ability to reliably weld individual nanowires and nanoobjects into complex geometries with controllable junctions. This represents a significant breakthrough for the current and future bottom-up localized assembly, integration, and repair of micro- and nanodevices.
Jan 12th, 2009
Stakeholders attending the second annual "Safety for Success" dialogue last October in Brussels agreed that while many activities had taken place during the past year towards the responsible development and regulation of nanotechnologies more effort was needed. Discussion highlighted three areas that require coordinated effort from all parties: 1) Developing trustworthy information on products containing nanomaterials that are on or near the market, and on how they are tested. 2) Meaningful public engagement on the basis of shared definitions of nanotechnology. 3) Ongoing regulatory reviews to provide clear guidance to industry on how to interpret regulatory frameworks, and clear indications to the public about action being taken in cases where relevant risk data is limited or uncertain. In addition, the meeting identified a number of key points that need to be addressed in order to meet these three priorities.
Jan 9th, 2009
Olfaction, our sense of smell, depends on the capability of specialized sensory cells in the nose to detect airborne odorant molecules. These olfactory cells contain specific protein molecules that acts as 'olfactory receptors' - they bind only to specific odorant molecules present in the air inhaled through the nose. When such a binding event occurs, the olfactory receptors change their shape and this deformation triggers chemical and electrical signals which are eventually transmitted to the brain through neurons. So, in a nutshell, this is how we smell. Human and especially some animal noses (think bomb-sniffing dogs) are very sophisticated and extremely sensitive gas sensors that can distinguish between very similar gas molecules. Researchers have been trying for a while to replicate the human olfactory sense - a concept called electronic nose (e-nose). While most nanotechnology-based efforts have focused on nanowires, new research conducted in Korea has demonstrated the detection of specific odorant molecules with a single-carbon-atomic resolution using a human olfactory receptor-functionalized carbon nanotube based sensor.
Jan 8th, 2009
One of the issues in using carbon nanotubes for applications is the challenge of separating metallic from semiconducting single-walled carbon nanotubes (SWCNT) after production. Developing a rapid and parallel technique for the electronic characterization of high-density arrays of SWCNT devices is essential for future large-scale production processes of nanoelectronics components. Currently used methods for electronic characterization of SWCNT devices and arrays are time consuming to set up, slow to execute, and not suitable for large-scale deployment. These methods include direct electron transport measurements and scanning probe microscopy, which can map the surface potential along a nanotube; again, a very slow technique with limited ability to be integrated into the process flow for microelectronic fabrication and characterization. More recent demonstrations of sorting nanotubes with DNA have been more promising but are very early stage. Researchers in Germany have now presented Voltage-Contrast Scanning Electron Microscopy (VC-SEM) as a new technique for the characterization of molecular electronic devices and device arrays.
Jan 7th, 2009
The emerging field of transparent and flexible electronics not only holds the promise of a new class of device components that would be more environmentally benign than current electronics; being able to print transparent circuits on low-cost and flexible plastic substrates also opens up the possibility of a wide range of new applications, ranging from windshield displays and flexible solar cells to clear toys and artificial skins and even sensor implants. Three broad application areas for this technology are taking shape: transparent displays; flexible displays; and transparent/flexible electronics. Traditional materials used for transparent electronics include indium tin oxide films and indium oxide nanowires. In their search for materials that can offer even higher mobility and therefore even better performance, researchers have turned to single-walled carbon nanotubes .New work at the University of Southern California has now demonstrated the great potential of massively aligned single-walled carbon nanotubes for high-performance transparent electronics.
Jan 6th, 2009
The flurry of recent announcements regarding reports, international cooperations, and new research activities that deal with the potential risks of manufactured nanomaterials is a clear indication that the field of nanotoxicology is gaining momentum - and not too soon. While there still is no coherent international approach to determining if and what risks are posed by what kind of nanotechnology materials, individual research groups are picking certain areas of concern and forge ahead with - often highly specific - toxicology studies. A lack of standards and definitions makes these early investigations hard to compare and sometimes they even contradict each other, a situation that is especially confusing in risk assessments of carbon nanotubes. Some studies, though, present findings that, on the face of it, are especially worrying in their potential implications and deserve much more attention to be sorted out one way or another. A recent report on the toxicity of metal nanoparticles in soil is such an example.
Jan 5th, 2009