Green Apples Are Crisp

“Apple has been criticized by some environmental organizations for not being a leader in removing toxic chemicals from its new products, and for not aggressively or properly recycling its old products,” said Jobs. “Upon investigating Apple’s current practices and progress towards these goals, I was surprised to learn that in many cases Apple is ahead of, or will soon be ahead of, most of its competitors in these areas.”

“Fortunately, all iPod displays already use LEDs for illumination, and therefore contain no mercury,” wrote Jobs. “We plan to introduce our first Macs with LED backlight technology in 2007. Our ability to completely eliminate fluorescent lamps in all of our displays depends on how fast the LCD industry can transition to LED backlighting for larger displays.”

Enter: OLED

The first light-emitting polymer device involved a single layer of poly. Multilayer OLEDs can have more than two layers to improve device efficiency. As well as conductive properties, layers may be chosen to aid charge injection at electrodes by providing a more gradual electronic profile, or block a charge from reaching the opposite electrode and being wasted.

A voltage is applied across the OLED such that the anode is positive with respect to the cathode. This causes a current of electrons to flow through the device from cathode to anode. Thus, the cathode gives electrons to the emissive layer and the anode withdraws electrons from the conductive layer; in other words, the anode gives electron holes to the conductive layer.

Soon, the emissive layer becomes negatively charged, while the conductive layer becomes rich in positively charged holes. Electrostatic forces bring the electrons and the holes towards each other and they recombine. This happens closer to the emissive layer, because in organic semiconductors holes are more mobile than electrons (unlike in inorganic semiconductors). The recombination causes a drop in the energy levels of electrons, accompanied by an emission of radiation whose frequency is in the viable region. That is why this layer is called emissive.

 

Just like passive-matrix LCD versus active-matrix LCD, OLEDs can be categorized into passive-matrix and active-matrix displays. Active-matrix OLEDs (AMOLED) can make higher resolution and larger size displays possible. For a high resolution display like a TV, a TFT backplane is necessary to drive the pixels correctly.

OLEDs enable a greater range of colors, brightness, and viewing angle than LCDs, because OLED pixels directly emit light. OLED pixel colors appear correct and unshifted, even as the viewing angle approaches 90 degrees from normal. LCDs use a backlight and cannot show true black, while an “off” OLED element produces no light and consumes no power. Energy is also wasted in LCDs because they require polarizers which filter out about half of the light emitted by the backlight. Additionally, color filters in color LCDs filter out two-thirds of the light.

OLEDs also have a faster response time than standard LCD screens. Whereas a standard LCD currently has an average of 4-8 millisecond response time, an OLED can have less than 0.01ms response time. 

The biggest technical problem for OLEDs is the limited lifetime of the organic materials. In particular, blue OLEDs historically have had a lifetime of around 14,000 hours (5 years at 8 hours a day) when used for flat-panel displays, which is lower than typical lifetime of LCD, LED or PDP technology—each currently rated for about 60,000 hours, depending on manufacturer and model. Toshiba and Panasonic have come up with a way to solve this problem with a new technology that can double the lifespan of OLED displays, pushing its expected life past that of LCD displays. A metal membrane helps deliver light from polymers in the substrate throughout the glass surface more efficiently than current OLED’s. The result is the same picture quality with half the brightness and a doubling of the screens expected life.

In 2007, experimental PLEDs were created which can sustain 400 cd/m² of luminance for over 198,000 hours for green OLEDs and 62,000 hours for blue OLEDs.

The intrusion of water into displays can damage or destroy the organic materials. Therefore, improved sealing processes are important for practical manufacturing and may limit the longevity of more flexible displays.

George Washington’s Distillery

• George Washington was the only founding father to commercially operate a distillery. 
• At peak production, the distillery utilized five stills and a boiler and produced 11,000 gallons of whiskey, yielding George Washington a better-than-average profit of $7500 in 1799. This made the distillery one of the most successful economic components of Mount Vernon. 
• The distillery is located down slope from the millrace of Mount Vernon plantation’s gristmill (built in 1771 and reconstructed in the 1930s). The gristmill and distillery complex also included a cellar for storage, a malt kiln, a cooperage for making barrels, hog and cattle pens, and quarters for millers, distillers, servants, and slaves. 
• The 75-by-30-foot distillery was among the largest structures of its kind in the eighteenth century. No operating distillery from the eighteenth century exists in America.

• George Washington began commercial distilling in 1797 at the urging of his Scottish farm manager, James Anderson, who had experience distilling grain in Scotland and Virginia. He successfully petitioned George Washington that Mount Vernon’s crops, combined with the large merchant gristmill and the abundant water supply, would make the distillery a profitable venture. 
• In February 1797, the cooperage at the mill was converted for distilling and two stills began operating.
• By the following summer, the makeshift distillery was so successful that Anderson lobbied George Washington to increase the number of stills. 
• Construction began in October of 1797 of a stone still house large enough for five stills. The foundation was large river rocks brought from the Falls of the Potomac and the walls of the distillery were made of sandstone quarried from Mount Vernon. 
• Anderson’s son, John, managed the production assisted by six enslaved African-Americans named Hanson, Peter, Nat, Daniel, James, and Timothy. The enlarged distillery was working by the spring of 1798. 
• That George Washington was willing to commit to distilling by building such a large structure is evidence of his desire to pursue the most innovative and creative farming practices of the day. Despite having no prior experience in distilling, he quickly became acquainted with the process. 
• The finished product was contained in barrels manufactured at the site and marketed to local farmers in Alexandria, and supplied the needs of the Mount Vernon plantation as well. The distillery produced a great quantity of waste and this slop was fed to over 150 hogs and cattle penned at the site.
• George Washington’s death in 1799 halted the brief success of the distillery and within a decade the building fell into disrepair and many of the stones were taken away to use in local construction projects. 
• In George Washington’s will the Gristmill, distillery and all associated buildings are left to Lawrence and Eleanor Parke Custis Lewis (Washington’s step-granddaughter and her husband). 
• In 1932, the property was purchased by the Commonwealth of Virginia. The Gristmill and miller’s cottage were reconstructed and the distillery outlined. Both were opened as a state park. 
• 1995 – The Mount Vernon Ladies’ Association enters agreement to restore the mill and research the property.
• 1997 – An archaeological survey of the area uncovered the “footprint” of the distillery, revealing an unusually large structure and a well-preserved site. 
• 1999 – Mount Vernon began an archaeological and documentary research program to find out as much historical data about the building as possible. 
• 2001 – The Distilled Spirits Council of the United States (DISCUS) provided a generous donation that allowed Mount Vernon to begin a five-year program of archaeological and documentary research, with the goal of reconstructing and interpreting George Washington’s distillery. 
• 2002 – Restoration completed at George Washington’s Gristmill and the site is dedicated April 12. Archaeology work continues at the distillery. 
• 2003 – Investigation continues as archaeologists dig down to the eighteenth-century construction layer.

TextCache

A TextCache is a text file which contains key-string pairs. The keys are strings which have the keyLeader character as its first character. The string associated with a key is separated from the key by the keySeparator character. The default value for keyLeader is an ampersand ‘@’ and the default for the keySeparator is the equals sign ‘=’. Everything following the keySeparator up to the next keyLeader or the end of the text file is the text string. An exception is that blank characters at the end of a string element are removed and any new line character in the text file is replaced by a blank. The key-string pairs are cached in memory after instantiation and the strings my be retrieved by using the respective keys.