Development of Advanced LED Phosphors by Spray-based Processes for Solid State Lighting

The overarching goal of the project was to develop luminescent materials using aerosol processes for making improved LED devices for solid state lighting. In essence this means improving white light emitting phosphor based LEDs by improvement of the phosphor and phosphor layer. The structure of these types of light sources, displayed in Figure 1, comprises of a blue or UV LED under a phosphor layer that converts the blue or UV light to a broad visible (white) light. Traditionally, this is done with a blue emitting diode combined with a blue absorbing, broadly yellow emitting phosphor such as Y{sub 3}Al{sub 5}O{sub 12}:Ce (YAG). A similar result may be achieved by combining a UV emitting diode and at least three different UV absorbing phosphors: red, green, and blue emitting. These emitted colors mix to make white light. The efficiency of these LEDs is based on the combined efficiency of the LED, phosphor, and the interaction between the two. The Cabot SSL project attempted to improve the over all efficiency of the LED light source be improving the efficiency of the phosphor and the interaction between the LED light and the phosphor. Cabot's spray based process for producing phosphor powders is able to improve the brightness of the powder itself by increasing the activator (the species that emits the light) concentration without adverse quenching effects compared to conventional synthesis. This will allow less phosphor powder to be used, and will decrease the cost of the light source; thus lowering the barrier of entry to the lighting market. Cabot's process also allows for chemical flexibility of the phosphor particles, which may result in tunable emission spectra and so light sources with improved color rendering. Another benefit of Cabot's process is the resulting spherical morphology of the particles. Less light scattering results when spherical particles are used in the phosphor layer (Figure 1) compared to when conventional, irregular shaped phosphor particles are used. This spherical morphology will result in better light extraction and so an improvement of efficiency in the overall device. Cabot is a 2.5 billion dollar company that makes specialized materials using propriety spray based technologies. It is a core competency of Cabot's to exploit the spray based technology and resulting material/morphology advantages. Once a business opportunity is clearly identified, Cabot is positioned to increase the scale of the production to meet opportunity's need. Cabot has demonstrated the capability to make spherical morphology micron-sized phosphor powders by spray based routes for PDP and CRT applications, but the value proposition is still unproven for LED applications. Cabot believes that the improvements in phosphor powders yielded by their process will result in a commercial advantage over existing technologies. Through the SSL project, Cabot has produced a number of different compositions in a spherical morphology that may be useful for solid state lights, as well as demonstrated processes that are able to produce particles from 10 nanometers to 3 micrometers. Towards the end of the project we demonstrated that our process produces YAG:Ce powder that has both higher internal quantum efficiency (0.6 compared to 0.45) and external quantum efficiency (0.85 compared to 0.6) than the commercial standard (see section 3.4.4.3). We, however, only produced these highly bright materials in research and development quantities, and were never able to produce high quantum efficiency materials in a reproducible manner at a commercial scale

Predicted and in situ performance of a solar air collector incorporating a translucent granular aerogel cover

This is the post-print version of the Article. The official published version can be accessed from the link below - Copyright @ 2012 ElsevierThere is an opportunity to improve the efficiency of flat plate solar air collectors by replacing their conventional glass covers with lightweight polycarbonate panels filled with high performance aerogel insulation. The in situ performance of a 5.4m2 solar air collector containing granular aerogel is simulated and tested. The collector is incorporated into the external insulation of a mechanically ventilated end terrace house, recently refurbished in London, UK. During the 7 day test period, peak outlet temperatures up to 45 °C are observed. Resultant supply and internal air temperatures peak at 25–30 and 21–22 °C respectively. Peak efficiencies of 22–36% are calculated based on the proposed design across a range of cover types. Measured outlet temperatures are validated to within 5% of their predicted values. Estimated outputs range from 118 to 166 kWh/m2/year for collectors with different thickness granular aerogel covers, compared to 110 kWh/m2/year for a single glazed collector, 140 k h/m2/year for a double glazed collector and 202 kWh/m2/year for a collector incorporating high performance monolithic aerogel. Payback periods of 9–16 years are calculated across all cover types. An efficiency up to 60% and a payback period as low as 4.5 years is possible with an optimised collector incorporating a 10 mm thick granular aerogel cover.This work is supported by the EPSRC, Brunel University, Buro Happold Ltd. and the Technology Strategy Board

Alloy 255 Bolsters Statue of Liberty

In the early 1980s, over 20,000 pounds of FERRALIUM® 255 alloy rectangular bars, nuts and bolts were donated to the Statue of Liberty-Ellis Island Foundation for restoration of the statue's interior supporting pylon. HASTELLOY® C-22® alloy was used to restore the spikes in the crown of the statue.Use of this image is restricted to projects related to Destination Indiana. IHS may not reproduce.Destination Indiana - Haynes International, a Century of Innovatio

TR's inauguration, 1905.

Scenes of TR's second inauguration on March 4, 1905 in Washington, D.C.: long panning shots of crowds gathered at the Capitol; on a platform erected on the East Front of the Capitol, Chief Justice Melville W. Fuller administers the presidential oath of office to TR as Chief Clerk of the Supreme Court James H. McKenney holds the Bible; TR speaks to crowd. Views of the West Point band and cadets, the Naval Academy band and midshipmen, men on horseback, and the Citizens Americus Club of Pittsburgh, carrying umbrellas, marching by and turning the corner off Pennsylvania Ave. onto Fifteenth St., NW. Views of the presidential escort, Squadron A of New York National Guard, mounted Rough Riders, Secret Service, detectives, and TR's carriage moving on their way to the Capitol. Beside TR in the carriage is Sen. John C. Spooner of Wis., chairman of the Committee on Inaugural Ceremonies; opposite but not visible are Sen. Henry Cabot Lodge of Mass. and Rep. John Dalzell of Penn., both members of the committee. On Pennsylvania Ave., two groups of officers on horseback, a civilian band, and cavalry and marching soldiers parade by.President Roosevelt, John C. Spooner, Henry Cabot Lodge, John Dalzell, Melville Weston Fuller, James H. McKenney.Duration: 4:33 (part 1), 3:48 (part 2), 1:13 (part 3) at 16 fps.Film sequence is repeated and does not follow order of actual events.Roosevelt Memorial Association numbers: RMA 301-01; RMA 301-2B. DLCSources used: Washington, D.C. Inaugural Committee, 1905. Inauguration of Theodore Roosevelt as President of the United States, March 4, 1905. [1905]; Washington post, March 5, 1905, p. 1-2; The New York herald, March 5, 1905, p. 2, p. 5; New York tribune, March 5, 1905, p. 1-3; LC Prints & Photographs Division presidential file; The Theodore Roosevelt Association...catalog, p. 154-155.Collection transferred to LC from National Park Service in 1967. Previous owners: Roosevelt Memorial Association; Paramount.The Theodore Roosevelt Association film collection : a catalog / prepared by Wendy White-Henson and Veronica M. Gillespie. Library of Congress, 1986

Chargeability measurements of selected pharmaceutical dry powders to assess their electrostatic charge control capabilities

The purpose of this study was to develop an instrument (the Purdue instrument) and the corresponding methodologies to measure the electrostatic charge development (chargeability) of dry powders when they are in dynamic contact with stainless steel surfaces. The system used an inductive noncontact sensor located inside an aluminum Faraday cage and was optimized to measure the charging capabilities of a fixed volume of powder (0.5 cc). The chargeability of 5,5-diphenyl-hydantoin, calcium sulfate dihydrate, cimetidine, 3 grades of colloidal silicon dioxide, magnesium stearate, 4 grades of microcrystalline cellulose, salicylic acid, sodium carbonate, sodium salicylate, spray-dried lactose, and sulfin-pyrazone were tested at 4 linear velocities, and the particle size distribution effect was assessed for 3 different grades of colloidal silicon dioxide and 4 different grades of micro-crystalline cellulose. The chargeability values exhibited a linear relationship for the range of velocities studied, with colloidal silicon dioxide exhibiting the maximum negative chargeability and with spray-dried lactose being the only compound to exhibit positive chargeability. The instrument sensitivity was improved by a factor of 2 over the first generation version, and the electrostatic charge measurements were reproducible with relative standard deviations ranging from nondetectable to 33.7% (minimum of 3 replicates). These results demonstrate the feasibility of using the Purdue instrument to measure the electrostatic charge control capabilities of pharmaceutical dry powders with a reasonable level of precision