No abstract

Green phosphorescent organic light-emitting devices (OLEDs) employing tris(2-phenylpyridine) iridium doped into a wide energy gap hole transport host have been studied. N,N,N′,N′-tetrakis(4-methoxyphenyl)-benzidine doped with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane is used as a hole injection and transport layer, 4,7-diphenyl-1,10-phenanthroline and cesium are coevaporated as a n-doped electron transport layer, and an intrinsic emission layer is sandwiched between these two doped layer. Such a p-i-n device features efficient carrier injection from both contacts into the doped transport layers and low ohmic losses in these highly conductive layers. Thus, low operating voltages are obtained compared to conventional undoped OLEDs. By modifying the device structure, we optimized the carrier balance in the emission layer and at its interfaces. For the optimized device, the maximum power efficiency is 53 lm/W, and a luminance of 1000 cd/m2 is reached at 3.1 V with a power efficiency of 45 lm/W.

One thousand three hundred seventy-nine nasopharyngeal carcinoma (NPC) patients were treated from March 1958 to December 1978. Twenty-two percent had stage I or II and 78% Stage III or IV had lesions. Two hundred twenty-Kv radiographs were used before 1960; and telecobalt was used from 1961 to 1978. Factors influencing the 5-year survival rate favorably are youth of patient, being female, pathologic condition (poorly differentiated carcinoma, 45.1% versus adenocarcinoma, 13%), stage (Stage I, 86%, Stage II, 59.5%; Stage III, 45.8%; Stage IV, 29.2%), decade admitted for treatment in the past (31% in the 1950s, 48.6% in the 1970s), total dose delivered to the nasopharynx (40 to 49 Gy, 46%; 70 to 79 Gy, 54.1%; 90 Gy or more, 64%) and prophylactic radiation to the neck regions (with prophylactic irradiation, 53.8%, without prophylactic irradiation, 23%). This implies that prophylactic radiation of the neck is crucial even without positive clinical metastasis. For those who have a residual tumor in the primary site when 70 Gy has been delivered, the total dose may be boosted to more than 90 Gy with the cone-down technique or on basis of adding 20 Gy to the dose at which the primary lesion disappeared grossly. The common postirradiation complications are: radiation myelitis, trismus, and otitis media. Because disease recurred in some patients after the fifth year, NPC patients should be followed for at least 10 years.