R&D UPDATES
05/01/2007
Nanocoating kills bacteria and viruses
LaamScience is working to commercialize a covalent nanocoating that, when subjected to light, produces agents that have been shown to kill or inactivate virtually all viruses and most bacteria. The company’s coating combines a process that amplifies the number of reactive sites on the fiber surface and covalently attaches a light-activated antimicrobial agent. The methodology is similar to photodynamic therapy that has already found substantial use in treating HIV and various cancers. The coating inactivates with virtually all viruses and does not require customized formulations.
LaamScience plans to optimize the technology for specific market applications, including personal respirator filters (masks); hospital-oriented furnishings, supplies, and furniture; and HVAC air filtration systems.
The light-activated coating is catalytic in nature, and the antimicrobial agents are continuously produced as long as the surface is exposed to visible light. Light momentarily elevates the coatings to a higher energy state. The coating transfers this energy to form an activated antimicrobial agent with a lifetime of less than a microsecond. The coating is regenerative, and the self-decontaminating surface remains virtually virus-free as long as it is exposed to visible light.
Test data have demonstrated a 99.2% to 99.99% kill rate of Vaccinia virus (a close relative of the smallpox virus) and influenza viruses (see table) as well as Gram-positive bacteria under light conditions of relatively short exposure at normal light intensities. Because the antimicrobial agent generation and interaction with the virus or Gram-positive bacteria will only occur in close proximity to the surface, LaamScience believes that it will not be harmful to humans or other large organisms.
Studies are continuing to improve viral inactivation using more-effective coatings with less-intense light, expanding the types of virus and bacteria tested, and showing the antimicrobial activity and ruggedness of the coatings in real-world testing.
Chemical components of the coating are well-characterized and are known entities that lessen the probability of biological incompatibilities. Furthermore, the coating is permanently bonded to the textile surface and does not contain leeching compounds. All components are water soluble, which aids safe manufacturing conditions. Biocompatibility testing (cytotoxicity, skin irritation, and skin sensitization) is underway.
UC claims world record in long, aligned nanotube arrays
University of Cincinnati (UC) engineering researchers have developed a composite catalyst and optimal synthesis conditions for oriented growth of multi-wall carbon nanotube arrays. And UC says it now leads the world in the synthesis of extremely long, aligned carbon nanotube arrays.
Research by Vesselin Shanov and Mark Schulz, co-directors of the University of Cincinnati Smart Materials Nanotechnology Laboratory, along with Yun YeoHeung and students, led to the invention of the method for growing long nanotube arrays. The researchers-in conjunction with First Nano, a division of CVD Equipment Corp.-have used the method to produce 18mm nanotube arrays on their EasyTube System using a chemical vapor deposition (CVD) process.
In a regrowth experiment on a separate substrate, the researcher produced an 11-mm-long array, which they were able to later peel completely off the substrate. Without additional processing, the same substrate was reused for a successive growth that yielded an 8-mm-long array.
The substrate is a multi-layered structure; a composite catalyst forms on top of an oxidized silicon wafer. Creating it requires a cleanroom environment and thin-film deposition techniques that can be scaled up to produce commercial quantities. Nanotube synthesis is carried out in a hydrogen/hydrocarbon/water/argon environment at 750°C.
The achievement fuels hope that continuous growth of nanotubes in the meter length range is possible. CVD Equipment plans to continue its partnership with UC to bring this technology into full-scale production. UC is also partnering with another company to produce long arrays that can be spun into fibers. The research has implications for medical, aerospace, electronic, and other applications.
New math tool simplifies complex data-and may help explain heavy nuclei
Despite advances in experimental nuclear physics, the most detailed probing of atomic nuclei still requires plenty of theory. The problem is that using theory to make meaningful predictions requires massive datasets that tax even high-powered supercomputers.
Now researchers from Michigan State and Central Michigan universities report dramatic reduction in complexity and computation time-and that may help address one of today’s most important questions in nuclear physics: What is the structure of heavy atomic nuclei?
At the heart of this question is the difficulty in modeling any system with multiple particles that interact via nuclear forces. The key is correlation, the idea that some pairs of electrons are strongly linked and related. Scientists have long known that focusing on the behavior of nucleon pairs helps describe the entire atomic nucleus-but until now, no one had used coupled-cluster theory with heavy atomic nuclei.
The researchers first used their high-performance computing centers to solve the weeks-long task of describing Nickel-56, in effect generating a yardstick by which to measure their abbreviated model. Next they compared their energy and wave function data. They report that coupled-cluster theory produced near-identical results, and the time spent crunching the numbers-on a standard laptop-was often measured in minutes or even seconds.