No abstract

Simple but exceptionally efficient 4-diphenylaminocarbazole host material, 4-DPACz, is presented and compared with its positional isomer, 1-DPACz. The shift of diphenylamino substituent from the 1-position to 4-position of carbazole resulted in an increase in the HOMO energy level as well as an increase in triplet energy level. Having a high triplet energy level (2.76 eV) and well-matched HOMO energy level (-5.61 eV), 4-DPACz showed reduced driving voltage and higher efficiencies for solution-processed green PhOLEDs compated to PVK as well as 1-DPACz. Maximum luminous, power, and external quantum efficiencies reaching to 47.9 cd A, 25.2 lm W, and 14.3%, respectively, were achieved with a device configuration of [ITO/PEDOT:PSS/4-DPACz:Ir(mppy)/TPBi/CsF/Al]. Additional enhancement of efficiencies of 4-DPACz was verified when incorporating another dopant, Ir(Si-bppy)(acac), resulting in 59.1 cd A, 29.5 lm W, and 15.8%. Furthermore, reduced efficiency roll-off was clearly observed for 4-DPACz compared with PVK. Such improved device characteristics of 4-DPACz were attributed to its high hole mobility and charge balance inside the emitting layer therof. The excellent results using such a simple-structured 4-DPACz could promote various applications of this 4-DPACz unit as a building block structure for further possible oligomeric, dendritic, and polymeric materials.

Most colonic multiple mucosa-associated lymphoid tissue (MALT) lymphomas are confirmed with a histologic and immunohistochemical staining of the mucosal biopsy specimen obtained during colonoscopic examinations. Endoscopically, colonic MALT lymphomas frequently appear as protruding and/or ulcerative lesions, and there are not so many reports of colonic MALT lymphoma as compared to the frequent reports of MALT lymphoma of stomach. We report a unique case of colonic MALT lymphoma presenting as a simple reddish discoloration of mucosa; this presentation has never been describe before. Our patient was a 47-yr-old male who suffered from tenesmus and mucoid stool. A colonoscopy was accomplished, followed by a histologic examination and we diagnosed a colonic MALT lymphoma. Staging of the disease was done because this was necessary for choosing the modality of treatments. The patient was then treated with polychemotherapy in conjunction with radiation therapy.

The efficiency of polymer light-emitting diodes was improved by synergistic effect of enhanced hole transport from mercaptoacids molecules and resonant coupling of Ag NPs introduced by ligand-exchange process.