Nanotechnology - Technology for every facet of life
Tuesday, September 30, 2014
Monday, September 29, 2014
Scientists grow a new challenger to graphene
A team of researchers from the University of Southampton’s Optoelectronics Research Centre (ORC) has announced a new way to fabricate a potential challenger to graphene.
Graphene, a single layer of carbon atoms in a honeycomb lattice, is increasingly being used in new electronic and mechanical applications, such as transistors, switches and light sources, thanks to the unprecedented properties it offers: very low electrical resistance, high thermal conductivity and mechanically stretchable yet harder than diamond.
Now, ORC researchers have developed molybdenum di-sulphide (MoS2), a similar material to graphene that shares many of its properties, including extraordinary electronic conduction and mechanical strength, but made from a metal (in this case molybdenum combined with sulphur).
This new class of thin metal/sulphide materials, known as transition metal di-chalcogenides (TMDCs), has become an exciting complimentary material to graphene. However, unlike graphene, TMDCs can also emit light allowing applications, such as photodetectors and light emitting devices, to be manufactured.
Until recently, fabrication of TMDCs, such as MoS2, has been difficult, as most techniques produce only flakes, typically just a few hundred square microns in area.
Dr Kevin Huang, from ORC who has led the research, explains: “We have been working on the synthesis of chalcogenide materials using a chemical vapour deposition (CVD) process since 2001 and our technology has now achieved the fabrication of large area (>1000 mm2) ultra- thin films only a few atoms thick. Being able to manufacture sheets of MoS2 and related materials, rather than just microscopic flakes, as previously was the case, greatly expands their promise for nanoelectronic and optoelectronic applications.”
Dr Huang and his team published their findings in the latest issue of the journal Nanoscale. They are currently working with several UK companies and universities, as well as leading international centres at MIT and Nanyang Technological University (Singapore).
Ref : http://www.southampton.ac.uk/mediacentre/news/2014/sep/14_172.shtml#.VCKK_pSSxo4
Friday, September 26, 2014
Nanotubes help healing hearts keep the beat
A team led by bioengineer Jeffrey Jacot and chemical engineer and chemist Matteo Pasquali created the patches infused with conductive single-walled carbon nanotubes. The patches are made of a sponge-like bioscaffold that contains microscopic pores and mimics the body's extracellular matrix.
The nanotubes overcome a limitation of current patches in which pore walls hinder the transfer of electrical signals between cardiomyocytes, the heart muscle's beating cells, which take up residence in the patch and eventually replace it with new muscle.
The work appears this month in the American Chemical Society journal ACS Nano. The researchers said their invention could serve as a full-thickness patch to repair defects due to Tetralogy of Fallot, atrial and ventricular septal defects and other defects without the risk of inducing abnormal cardiac rhythms.
The original patches created by Jacot's lab consist primarily of hydrogel and chitosan, a widely used material made from the shells of shrimp and other crustaceans. The patch is attached to a polymer backbone that can hold a stitch and keep it in place to cover a hole in the heart. The pores allow natural cells to invade the patch, which degrades as the cells form networks of their own. The patch, including the backbone, degrades in weeks or months as it is replaced by natural tissue.
Researchers at Rice and elsewhere have found that once cells take their place in the patches, they have difficulty synchronizing with the rest of the beating heart because the scaffold mutes electrical signals that pass from cell to cell. That temporary loss of signal transduction results in arrhythmias.
Nanotubes can fix that, and Jacot, who has a joint appointment at Rice and Texas Children's, took advantage of the surrounding collaborative research environment.
"This stemmed from talking with Dr. Pasquali's lab as well as interventional cardiologists in the Texas Medical Center," Jacot said. "We've been looking for a way to get better cell-to-cell communications and were concentrating on the speed of electrical conduction through the patch. We thought nanotubes could be easily integrated."
Thursday, September 25, 2014
Future flexible electronics based on carbon nanotubes
Rsearchers from the University of Texas at Austin and Northwestern University have demonstrated a new method to improve the reliability and performance of transistors and circuits based on carbon nanotubes (CNT), a semiconductor material that has long been considered by scientists as one of the most promising successors to silicon for smaller, faster and cheaper electronic devices. The result appears in a new paper published in the journal Applied Physics Letters, from AIP Publishing.
In the paper, researchers examined the effect of a fluoropolymer coating called PVDF-TrFE on single-walled carbon nanotube (SWCNT) transistors and ring oscillator circuits, and demonstrated that these coatings can substantially improve the performance of single-walled carbon nanotube devices. PVDF-TrFE is also known by its long chemical name polyvinyledenedifluoride-tetrafluoroethylene.
"We attribute the improvements to the polar nature of PVDF-TrFE that mitigates the negative effect of impurities and defects on the performance of semiconductor single-walled carbon nanotubes," said Ananth Dodabalapur, a professor in the Cockrell School of Engineering at UT Austin who led the research. "The use of [PVDF-TrFE] capping layers will be greatly beneficial to the adoption of single-walled carbon nanotube circuits in printed electronics and flexible display applications."
The work was done in collaboration between Dodabalapur's group at UT Austin and Mark Hersam's group at Northwestern University as part of a Multi-University Research Initiative (MURI) supported by the Office of Naval Research.
A potential successor to silicon chips
Single-walled carbon nanotubes (SWCNT) are just about the thinnest tubes that can be wrought from nature. They are cylinders formed by rolling up a material known as graphene, which is a flat, single-atom-thick layer of carbon graphite. Most single-walled carbon nanotubes typically have a diameter close to 1 nanometer and can be twisted, flattened and bent into small circles or around sharp bends without breaking. These ultra-thin carbon filaments have high mobility, high transparency and electric conductivity, making them ideal for performing electronic tasks and making flexible electronic devices like thin film transistors, the on-off switches at the heart of digital electronic systems.
"Single-walled carbon nanotube field-effect transistors (FETs) have characteristics similar to polycrystalline silicon FETs, a thin film silicon transistor currently used to drive the pixels in organic light-emitting (OLED) displays," said Mark Hersam, Dodabalapur's coworker and a professor in the McCormick School of Engineering and Applied Science at Northwestern University. "But single-walled carbon nanotubes are more advantageous than polycrystalline silicon in that they are solution-processable or printable, which potentially could lower manufacturing costs."
Tuesday, September 16, 2014
Nano engineering advances bone-forming material
The advancement means the successful use of synthetic materials in bone grafts for human patients is a step closer. The material could also have potential future applications in fracture repair and reconstructive surgery.
Currently the patient's own bone, donated bone or artificial materials are used for bone grafts but limitations with all these options have prompted researchers to investigate how synthetic materials can be enhanced.
Dr Eddy Poinern and his team from the Murdoch Applied Nanotechnology Research Group worked with powdered forms of the bio ceramic hydroxyapatite (HAP) to form pellets with a sponge-like structure which were then successfully implanted behind the shoulders of four sheep by collaborators from the School of Veterinary and Life Sciences at Murdoch University.
HAP is already being used in a number of biomedical applications such as bone augmentation in dentistry because of its similarity to the inorganic mineral component of human bone. But treatments of HAP so that it can be successfully used in a bone graft have yet to be developed because of the complexities involved with compatibility and HAP's load bearing limitations.
FDA Advisory Committee Votes 14-1 in Favor of Saxenda (liraglutide) for Obesity
In continuation of my update on Lirglutide
Novo Nordisk today announced that the Endocrinologic and Metabolic Drugs Advisory Committee (EMDAC) of the Food and Drug Administration (FDA) has completed its meeting regarding the New Drug Application (NDA) for Saxenda, the intended brand name for liraglutide 3 mg, a once-daily human GLP-1 analogue for the treatment of obesity.
Monday, September 15, 2014
More efficient fuel cells for vehicles: Angling chromium to let oxygen through -- ScienceDaily
Rsearchers have been trying to increase the efficiency of solid oxide fuel cells by lowering the temperatures at which they run. More efficient fuel cells might gain wider use in vehicles or as quiet, pollution-free, neighborhood electricity generating stations. A serendipitous finding has resulted in a semiconducting material that could enable fuel cells to operate at temperatures two-thirds lower than current technology, scientists reported August 18 in Nature Communications.
Friday, September 12, 2014
Graphene paints a corrosion-free future: Keep food fresh longer? -- ScienceDaily
A thin layer of graphene paint can make impermeable and chemically resistant coatings which could be used for packaging to keep food fresh for longer and protect metal structures against corrosion, new findings from The University of Manchester show.
Friday, September 5, 2014
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