Archive for May 2009
You are browsing the archives of 2009 May.
You are browsing the archives of 2009 May.
After nearly a year of behind-the-scenes planning, the American Ceramic Society just announced that it is launching a new journal on advanced glass research. This new peer-reviewed quarterly will be called the International Journal of Applied Glass Science.
The journal’s debut is timely as new generations of glass and glass-related materials are increasingly being called upon to play a role in many of the world’s emerging technologies, including energy, medical, transportation, construction, environmental, optical and defense technologies spheres.
ACerS President John Kaniuk says IJAGS will encompass the description, application, modeling, experimental investigation and manufacture of glass materials.
L. David Pye, dean and professor of glass science, emeritus, at the New York State College of Ceramics at Alfred University has agreed to serve as the founding editor of IJAGS. Pye will be aided by an international advisory board. Pye, who is the past president of ACerS, says the new journal “will advance all of the branches of materials science and engineering, and it will support the growing role of glass applications throughout society.” He said the first issue will be released in March 2010.
ACerS says the production of IJAGS will be done in partnership with leading science publisher Wiley-Blackwell. ACerS and Wiley-Blackwell already have a strong publishing track record and jointly produce two other peer-reviewed journals: The Journal of the American Ceramic Society and the International Journal of Applied Ceramic Technology. These journals are among the most cited ceramic publications in the world.
Two Northwestern University researchers believe they have developed a new dual-use tool and methods for delivering drugs and other nanoscale therapeutic materials to cells using coated nanodiamonds. The researchers, Horacio Espinosa, professor of mechanical engineering, and Dean Ho, assistant professor of mechanical and biomedical engineering, at Northwestern’s McCormick School of Engineering and Applied Science, call their tool a Nanofountain Probe
To understand the probe’s abilities, Espinosa and Ho use two analogies. First, they say it’s like a fountain pen containing an “ink” of drug-coated nanodiamonds that can then be written with. The other analogy is to a syringe - albeit a very tiny one - so small that it can deliver materials to individual cells. This could aid in the precise delivery of toxic chemotherapy drugs in cancer patients.
The research group has already begun trials in which they inject doses of nanodiamonds into both healthy and cancerous cells.
In a story on the McCormick School’s website, Ho said, “This allows us to deliver a precise dose to one cell and observe its response relative to its neighbors. This will allow us to investigate the ultimate efficacy of novel treatment strategies via a spectrum of internalization mechanisms.”
In a different application, they are using the nanofountain probe to lay down arrays of drug-coated nanodiamonds on glass substrates. This array-production aspect of their work mainly serves to provide a proof-of-concept for future manufacturing of patch-like devices for the delivery of nanomaterials. The probe provides a method for controlling dosage and precisely distributing the materials upon the substrate. The patch approach, itself, is advantageous because it theoretically provides a way of delivering precise, low-level amounts a chemotherapy drugs for months at a time. Ho has already worked with a polymer patch covered with a layer of drug-coated nanodiamonds, which moderate the release of the drug.
The use of films containing drug-coated nanodiamonds isn’t particularly novel, but Espinosa and Ho are taking it farther by offering a method to have patterned arrays composed of multiple drugs. Ho says. “This allows high-fidelity spatial tuning of dosing in intelligent devices for comprehensive treatment.” They claim the patterning resolution represents an improvement of three orders of magnitude over previous schemes to deposit nanodiamonds.
“One of the most significant aspects of this work is the Nanofountain Probe’s ability to deliver nanomaterials coated with a broad range of drugs and other biological agents,” Espinosa says. “The injection technique is currently being explored for delivery of a wide variety of bio-agents, including DNA, viruses and other therapeutically relevant materials.”
Ho and Espinosa also think the high-resolution ability of their probe will also be a benefit to the development of nanoelectronics, providing a controlled way to “seed” the growth of diamond thin films. Nanodiamonds have also proven effective in seeding the growth of diamond thin films
Prepared by the “How It’s Made” group at the Discovery Channel, this video is an introductory look at the fundamentals of preparing, coating, drawing and annealing the thin threads of glass used in fiber optics.
Researchers at Rensselaer Polytechnic Institute tell us of a discovery that might lead to new systems for cooling and displacing heat from computer chips, a critical issue in the semiconductor industry.
The RPI researchers say they have linked heat transfer and bond strength of materials. Their study is based on the idea that the speed at which heat moves between two materials that are in contact with one another is a potent indicator of the strength of the bond between them. The study, in this case, of one solid and one liquid, also shows that the heat flow from one material to another can be altered by painting a thin atomic layer between the two materials. The changed interface changed the interaction between the materials.
Kablinski and Garde used molecular dynamics simulations to measure the heat flow between solid surfaces and water. They simulated surface chemistries and discovered that thermal conductivity was proportional to how strongly the liquid adhered to the solid. Garde says, “We can use this new technique to characterize systems that are very difficult or impossible to characterize by other means.”
The results have implications for heat-transfer applications and processes, including boiling and condensation as well as the behavior of water at various sold interfaces. The study helps researchers better understand how water sticks to or flows past a surface.
Research being conducted at Sandia National Lab might eventually be applied to an optical detector with nanometer-scale resolution, ultra-tiny digital cameras, solar cells with more light absorption capability and a better device for genome sequencing. However, the near-term purpose of the research is basic science.
The Sandia researchers report they have created the first carbon nanotube device that can detect the entire visible spectrum of light. This might allow them to study single-molecule transformations, how the molecules respond to light and change shape as well as other fundamental interactions between molecules and nanotubes.
As with many other recent studies, the researchers went back to nature, in this case the human eye, and they improved on the model. A cascade of chemical and electrical events that ultimately trigger nerve impulses occur when light strikes a chromophore on the molecules in the eye’s retina. Likewise, when light strikes a chromophore in the nanoscale color detector, it causes a conformational change in the molecule. This, in turn, causes a threshold shift on a transistor made from a single-walled carbon nanotube.
“In our eyes the neuron is in front of the retinal molecule, so the light has to transmit through the neuron to hit the molecule,” says Sandia researcher Xinjian Zhou. “We placed the nanotube transistor behind the molecule - a more efficient design.”
That carbon nanotubes are light sensitive has been known for a long time, but earlier efforts using an individual nanotube were only able to detect light in narrow wavelength ranges, and then only at laser intensities. The Sandia team nanodetector is orders of magnitude more sensitive, down to about 40 W/m2, which is about 3 percent of the density of sunshine reaching the ground. “Because the dye is so close to the nanotube, a little change turns into a big signal on the device,” says Zhou.
Zhou and his colleagues François Léonard, Andy Vance, Karen Krafcik, Tom Zifer and Bryan Wong created the device, which they described in a paper published in Nano Letters. Zhou and Krafcik created a tiny transistor made from a single carbon nanotube. They deposited carbon nanotubes on a silicon wafer and used photolithography to define electrical patterns to make contacts. Meanwhile, Vance and Zifer synthesized molecules to create three types of chromophores that respond to either red, green or orange bands of the visible spectrum. Zhou immersed the wafer in the dye solution until the chromosphores attached themselves to the nanotubes.
“Detection is now limited to about 3 percent of sunlight, which isn’t bad compared with a commercially available digital camera,” says Zhou. “I hope to add some antennas to increase light absorption.”
The team is now working on detecting infrared light. “We think this principle can be applied to infrared light, and there is a lot of interest in infrared detection,” says Vance. “So we’re in the process of looking for dyes that work in infrared.”
“A large part of why we are doing this is not to invent a photo detector, but to understand the processes involved in controlling carbon nanotube devices,” says Léonard, author of The Physics of Carbon Nanotubes, published September 2008.
The next step is to create a nanometer-scale photovoltaic device. Such a device on a larger scale could be used as an unpowered photo detector or for solar energy. “Instead of monitoring current changes, we’d actually generate current,” says Vance. “We have an idea of how to do it, but it will be a more challenging fabrication process.”