A new concept for organic light-emitting diodes (OLEDs) is presented, which is called exciplex-sensitized triplet-triplet annihilation (ESTTA). The exciplex formed at the organic heterojunction interface of 4,4',4″-tris(N-3-methyphenyl-N-phenyl-amino) triphenylamine and 9,10-bis(2'-naphthyl) anthracene (ADN) is used to sensitize the triplet-triplet annihilation (TTA) process on the ADN molecules. This results in a turn-on voltage (2.2 V) of the blue emission from the OLED below the bandgap (2.9 eV). From the transient electroluminescence measurement, blue emission totally came from the TTA process without direct recombination on the ADN molecules. The blue singlet exciton from the TTA process can be quenched by energy transfer to the exciplex, as revealed by transient photoluminescence measurements. This can be prevented by blocking the energy transfer path and improving the radiative recombination rate of blue emission. With the insertion of the "triplet diffusion and singlet blocking (TDSB)" layer and the incorporation of the dopant material, an ESTTA-OLED with external quantum efficiency of 5.1% was achieved, which consists of yellow and blue emission coming from the exciplex and ESTTA process, respectively.

Tag anti-collision has long been an important issue in RFID systems. To accelerate tag identification, some researchers have recently adopted bit tracking technology that allows the reader to detect the locations of collided bits in a collision slot. However, these methods still encounter the problem of too many collisions occurring at the beginning of identification. This paper proposes an optimal binary tracking tree protocol (OBTT) that tries to separate all of the tags into smaller sets to reduce collisions at the beginning of identification. Using bit tracking technology, OBTT mainly adopts three proposed approaches, bit estimation, optimal partition, and binary tracking tree. Bit estimation first estimates the number of tags based on the locations of collided bits. Optimal partition then determines the optimal number of the initial sets based on this estimation. Binary tracking tree lets the tag utilize one counter to achieve the split during the identification process. This paper formally analyzes the slot efficiency of OBTT, which represents how many tags can be identified in a slot. Results show that the slot efficiency is close to 0.614, the highest value published to date. Considering slot lengths, OBTT further determines the optimal number of the initial sets to minimize the identification delay. The analytical results show that the delay efficiency of OBTT achieves 0.750, where delay efficiency represents the number of tags that can be identified in a baseline slot, the length of which is the complete ID sent by the tag. The simulation results show that OBTT outperforms other existing algorithms. Index Terms-Anti-collision, bit tracking, Manchester code, RFID, tag identification.Yuan-Cheng Lai received the Ph.D. degree in computer and information science from National Chiao Tung University, Taiwan, in 1997.He joined the faculty of Information Management, National Taiwan University of Science and Technology, Taiwan, in 2001 and has been a Professor since 2008. Now, he is a Distinguished Professor at the university. He has published over 170 research papers and six Chinese books about computer networks. His research interests include performance analysis, protocol design, wireless networks, and network security.Ling-Yen Hsiao received the B.S.

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Flexible work practices and team-based management could be considered by nursing management to lessen job demand pressure and to facilitate job engagement and participation among nurses, thus promoting a better balance between work and personal life.