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Nanotechnology Spotlight – Latest Articles

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Showing Spotlights 833 - 840 of 2140 in category (newest first):

 

Why is the (nano-)dose question so important?

quantum_dotsA substance might potentially be harmful or even toxic for a biological system, provided that the quantity or the concentration (the "dose") is high enough. This principle forms the basis for health standards which determine the maximum permissible concentration of contaminations, for example in food, water or in the environment. Dose calculation is of high relevance for risk assessment as well as for regulations, for instance to determine the maximum allowable concentration of chemicals and particles or to determine other limits which do not cause health problems. In the case of nanomaterials, especially for nanoparticles there is to date, no limit regulation or any other regulation referring to dose, because the definition of dose for nanoparticles does not exist. The wherefores will be explained in this dossier.

Posted: May 24th, 2012

Consumers, nanotechnology and responsibilities: Operationalizing the risk society

nano-ninaRisks are high on the agenda in our society, to the extent that we might refer to the society as a risk society. Our society experiences emerging technologies, like nanotechnology. Different actors respond to this in a variety of ways. Among these are the consumers, an important, but neglected category of actors in this context. Arguably it is in our role as consumers we first encountered nanotechnology, in the form of nano-enabled products at the consumers market. What consumers think and do, reacting to the mixed messages about benefits and risks of nanotechnology, contributes to how the risk society (with regard to nanotechnology) is developed, and in that sense becomes operationalized. The theme of this thesis is not just the responses of consumers (and how others perceive these) to the introduction of nanotechnology, but also a case study of how the risk society can be operationalized.

Posted: May 22nd, 2012

Nitric oxide nanoparticles effectively treat candidal burn infections

nanoparticlesCandida albicans is a leading fungal cause of burn infections in hospital settings. The prevalence of invasive candidiasis in burn cases varies widely, but it accounts as high as 23% of severe infection with a mortality rate ranging from anywhere to 14% to 70%. In a recent pre-clinical study, a nitric oxide releasing nanoparticle platform, which has previously been shown to be antibacterial to both gram positive and negative bacteria, as well as an accelerator of wound healing in excisional animal models, was found to be efficacious in clearing candidal burn infections in mice. This study represents one of many pre-clinical investigations demonstrating the efficacy of the NO nanoparticles as a broad spectrum antimicrobial agent as well as wound healing accelerant.

Posted: May 21st, 2012

International standards for trade in nanotechnology foods?

fruitsNanotechnology-based food and health products and food packaging materials are available to consumers in some countries already, and additional products and applications are currently in the research and development stage, and some may reach the market soon. In view of such progress, it is expected that nanotechnology-derived food products will be increasingly available to consumers worldwide in the coming years. Some of these products appear to already be in commercial use in other countries, raising the likelihood that they could become a part of our food supply in the near future, if they are not already. This article looks at how regulators are dealing with the pressures to commercialize nanotech foods and food packaging.

Posted: May 16th, 2012

Microcavity vastly enhances photoresponse of graphene photodetectors

graphene_photodetectorThere is currently a very strong interest in using graphene for applications in optoelectronics. Graphene-based photodetectors have been realized before. By using graphene, researchers make use of the internal electric field that exists at the interface of graphene and metal. However, the low optical absorption of graphene - only 2.3 % due to its monoatomic thickness - leads to a low responsivity of these devices. Several groups worldwide are therefore currently pursuing different approaches to increase the interaction length of light with graphene and enhance the optical absorption. One novel approach is based on the integration of graphene into an optical microcavity. The increased electric field amplitude inside the cavity causes more energy to be absorbed, leading to a significant increase of the photoresponse.

Posted: May 14th, 2012

Carbon nanotubes enhance performance of heat transfer nanofluids

carbon_nanotubesNanofluids - engineered colloidal suspensions of nanoparticles in a base fluid - are attracting a great deal of interest with their enormous potential to provide enhanced performance properties. Particularly with respect to heat transfer, and compared with more conventional heat transfer fluids (i.e. coolants) currently available, nanofluidic coolants exhibit enhanced thermal conductivity. Attempts to increase the thermal conductivity of heat transfer fluids using nanoparticles has been an active research area over the past decade. However, these attempts have not resulted in a significant improvement in conductivity due to the low thermal conductivity of nanoparticles and high thermal boundary resistance around the 0-dimensional nanoparticles. Researchers have therefore decided to produce a nanofluid using single-walled carbon nanotubes because of their much higher thermal conductivity and their ability to form connected networks with the neighboring carbon nanotubes, thereby increasing the heat transfer path.

Posted: May 11th, 2012

Graphene quilts take the heat away

grapheneGallium Nitride (GaN) is a semiconductor material commonly used in bright light-emitting diodes since the 1990s, which are now found in traffic lights and solid-state lighting. Thanks to its wide band gap, this very hard semiconductor material also finds applications in optoelectronic, high-power and high-frequency devices. However, a severe problem that afflicts high-power GaN electronic and optoelectronic devices is self-heating and the difficulties of heat removal. Researchers have now found an unusual solution for the thermal management problem of gallium-nitride technology: They demonstrated that thermal management of GaN transistors can be substantially improved via introduction of alternative heat-escaping channels implemented with graphene multilayers.

Posted: May 10th, 2012

Topological transitions in metamaterials could lead to more efficient solar cells, sensors, and LEDs

metamaterialPhysicists have uncovered a new method to manipulate light by borrowing an idea from the field of mathematical topology - topology is the mathematical field dealing with the properties of objects undergoing deformations, such as stretching and twisting. They created an artificial material, a "metamaterial", that can transform from regular dielectric - a substance like glass or plastic, which does not conduct electricity - to a medium that behaves like metal (reflects) in one direction and like dielectric (transmits) in the other. The research team expects optical topological transition to be the basis for a number of applications of both fundamental and technological importance through use of metamaterial-based control of light-matter interaction.

Posted: May 9th, 2012