Looking like a liquid opal, submicroscopic balls of plastic--the same polystyrene used to make coffee cups--sit embedded in a water-based gel. These polymerized crystalline colloidal array (PCCA) can do amazing and useful things. For instance, University of Pittsburgh chemists John H. Holtz and Sanford A. Asher discovered they can use the PCCAs as chemical sensors to make chemical measurements. "Colloidal arrays have fascinating optical properties," says Asher. "Because of their electrical charge, they self organize into a cubic structure where all the plastic balls are equally spaced. Depending on this spacing, the colloidal array diffracts (or reflects) visible light, much in the same way that an opal does, and you get intense colors." The chemists have made PCCAs that are highly sensitive to particular chemical species or thermal changes. If exposed to certain chemicals, such as lead, the array swells, changing the spacing. That causes the PCCA to diffract light at new wavelengths, and it changes color. Asher's group has demonstrated that the arrays are effective at detecting lead concentrations in water, and that once the lead is cleaned from the array it can be reused without any loss of sensitivity. FAX Kevin Roark at (412) 624-4895.
We looked at a number of sources to determine this year's greenest cars, from KBB to automotive trade magazines to environmental organizations. These 14 cars emerged as being great at either stretching fuel or reducing carbon footprint.
A quick look into the merger of two powerhouse 3D printing OEMs and the new leader in rapid prototyping solutions, Stratasys. The industrial revolution is now led by 3D printing and engineers are given the opportunity to fully maximize their design capabilities, reduce their time-to-market and functionally test prototypes cheaper, faster and easier. Bruce Bradshaw, Director of Marketing in North America, will explore the large product offering and variety of materials that will help CAD designers articulate their product design with actual, physical prototypes. This broadcast will dive deep into technical information including application specific stories from real world customers and their experiences with 3D printing. 3D Printing is