Showing Spotlights 1169 - 1176 of 2383 in category All (newest first):
Lithium-ion batteries have been widely used in many electronic devices that are important to our daily life. However, after a steady improvement of some 10-15% during the last two decades, the energy density of lithium-ion batteries is now approaching its theoretical limit set by the energies of cathode and anode materials used in these batteries. Therefore, in recent years, the pursuit of the next generation of energy storage systems has been intense globally. Among various electrochemical energy storage systems explored to date, the lithium-air (Li-air) battery is one of the most promising technologies, with a theoretical energy density nearly ten times that of conventional lithium-ion batteries. A novel air electrode consisting of an unusual hierarchical arrangement of functionalized graphene sheets delivers an exceptionally high capacity.
Nov 2nd, 2011
Using the CVD process, manufacturers can combine a metal catalyst such as iron with reaction gases such as hydrocarbon to form carbon nanotubes inside a high-temperature furnace. This process creates CNTs that are subsequently deposited in a collection environment and harvested into the desired end-product structural form. Understanding the processes in CVD growth of carbon nanotubes is important for their high yield and extended production. But even today, some 20 years since their discovery, the finer details of CNT growth mechanisms remain poorly understood. One of the issues that manufacturers have to grapple with is the levelling off and ultimate stoppage of CNT growth several minutes into the CVD process. This is referred to as catalyst poisoning - an inactivation or poisoning process of catalyst particles that has been attributed to an overcoat of amorphous carbon.
Oct 31st, 2011
Lipids are the main component of the outermost membrane of cells. Their role is to seperate the inner and outer media of the cell and prevent any ionic current between these two media. Because of this last property, lipid layers can be thought of as good ultra-thin insulators that could be used in the development of electronic devices. So far though, because of their inherent instability in air, their use in advanced processes has been limited. This might change, though, since researchers in France have shown the possibility to stabilize by polymerization a lipid monolayer with a thickness of 2.7 nm directly at the surface of H-terminated silicon surface therefore opening a whole new world of possibilities of the use of these layers. Now, they reported the electrical performance of stabilized lipid monolayers on H-terminated silicon.
Oct 27th, 2011
Analyzing the physicochemical processes that take place at surfaces and interfaces is an important aspect in materials science, catalysis, biochemistry and other fields. For many years, surface scientists have relied on powerful tools like X-ray Photoelectron Spectroscopy (XPS) and other spectroscopy techniques based on the detection of electrons. XPS reveals the elemental composition and chemical and electronic states of surfaces by irradiating a material with a beam of X-rays and measuring the energy and electrons that escape. However, it still remains a great experimental challenge to adapt powerful, surface sensitive tools such as XPS or to explore objects at ambient conditions. Researchers now demonstrate that graphene oxide membranes are a very promising window material for environmental cells to enable XPS studies of samples immersed in liquid or dense gaseous media.
Oct 25th, 2011
Breath analysis has been recognized as an increasingly accurate diagnostic method to link specific gaseous components in human breath to medical conditions and exposure to chemical compounds. Sampling breath is also much less invasive than testing blood, can be done very quickly, and creates as good as no biohazard waste. A recent review article in Environmental Science and Technology focuses on breath analysis as a tool for assessing environmental exposure and provides a good overview of the current state of diagnostic tools, leading studies in this field, and emerging technologies for hand-held breath analyzers. After describing the basics of breath analysis as a diagnostic tool, the authors discuss emerging chemical sensor technology ('electronic noses'), in particular two nanotechnology-based approaches, that are suitable to identify target analytes in breath.
Oct 24th, 2011
More than 100 companies around the world today are manufacturing carbon nanotubes and this number is expected to increase to more than 200 within the next five years, while there are more than 1,000 companies and institutions that are actively engaged in CNT research and development. This article looks at the market size, applications, processing technology and end-user products of carbon nanotubes. In addition, the study looks at industry leaders in the value chain, potential applications, products which are under development and are likely to enter the market in the next five to ten years. For this study, we have surveyed industry professionals/stakeholders in the CNTs value chain, extracted information from our proprietary in-house databases/ inter-linked databases as well as researched other primary and secondary sources and triangulated data and the findings are presented in this article.
Oct 20th, 2011
How often have you crumpled a sheet of paper in frustration and thrown it into the bin without further thought? You'll be amazed to hear that researchers - inspired by a trash can full of crumpled-up papers - have now applied this to solving one of the challenges of scaling up production of graphene sheets. One of the fascinating properties of crumpled paper balls is their strain-hardening effect - the harder you compress them, the stiffer they become, due to the formation of folded ridges that increase the strength. A similar effect has now been found in crumpled graphene balls. These crumpled particles exhibits strain-hardening behaviors, thus making them remarkable resistant to aggregation in both solution and dried states.
Oct 18th, 2011
The catalytic conversion of chemical to mechanical energy, which is ubiquitous in biological systems, also is the basis for many of the engine systems that nanotechnology researchers are developing. Catalytic 'engines' will be key components of active micron- and sub-micron scale systems for controlled movement, particle assembly, and separations. So far, most of these catalytic micro- and nanomotors use hydrogen peroxide as the fuel. The major problem associated with this is that the produced oxygen bubbles make the observation and detailed study of these motors difficult. Researchers at the Pennsylvania State University have now introduced a new bubble-free, high efficient nanomotor system that involves the operation of a miniaturized copper-platinum nanobattery.
Oct 17th, 2011