Long-Range π-Conjugation in Phenothiazine-containing Donor-Acceptor Dyes for Application in Dye-Sensitized Solar Cells.

Four organic donor-π-bridge-acceptor dyes containing phenothiazine as a spacer and cyanoacrylic acid as an acceptor were synthesized and tested as sensitizers in dye-sensitized solar cells (DSCs). The influence of iodide- and cobalt-based redox electrolytes on the photovoltaic device performance was investigated. In these new dyes, systematic π-conjugation was extended by inserting one or two phenothiazine moieties and investigated within the context of the resulting photoinduced charge-transfer properties. A detailed investigation, including transient absorption spectroscopy and quantum chemical methods, provided important information on the role of extended π-conjugation on the photophysical properties and photovoltaic device performance. Overall, the results showed that the extension of π-conjugation by one phenothiazine unit resulted in the best device performance owing to reduced recombination rates, whereas extension by two phenothiazine units reduced dye adsorption on TiO2 probably owing to the increase in molecular size. The performance of the dyes in DSCs was found to be a complex interaction between dye structure and size.

Synthesis and Electroluminescence Property of New Hexaphenyl Benzene Derivatives Including Emitting Core for OLED.

Three new emitting compounds of 5P-2TPA, 5P-2An and 5P-2Py for OLED based on hexaphenyl benzene moiety were synthesized. Physical properties were systematically examined by the change of the substitution groups of the synthesized materials. Photoluminescence (PL) spectrum of the synthesized materials showed maximum emitting wavelengths of about 437~488 nm in solution state and 457~516 nm in film state, indicating blue emission color. OLED devices were fabricated by the synthesized compounds using vacuum deposition process as an emitting layer. Device structure was ITO/2-TNATA 60 nm/NPB 15 nm/EML 35 nm/TPBi 20 nm/LiF 1 nm/Al 200 nm. External quantum efficiencies and CIE values of 5P-2TPA, 5P-2An and 5P-2Py were 3.34, 1.06 and 2.06% and (0.14, 0.12), (0.23, 0.45) and (0.24, 0.45), respectively. The three compounds exhibited thermal stablility with high Td of 426 °C, 449 °C and 467 °C.

Synthesis and electroluminescence property of new hexaphenylbenzene derivatives including amine group for blue emitters.

Three new blue-emitting compounds of 5P-VA, 5P-VTPA, and 5P-DVTPA for organic light-emitting diode (OLED) based on hexaphenylbenzene moiety were demonstrated. Physical properties by the change of the substitution groups of the synthesized materials were systematically examined. Photoluminescence spectrum of the synthesized materials showed maximum emitting wavelengths of about 400 to 447 nm in solution state and 451 to 461 nm in film state, indicating deep blue emission color. OLED devices were fabricated by the synthesized compounds using vacuum deposit process as an emitting layer. The device structure was ITO/2-TNATA 60 nm/ NPB 15 nm/ EML 35 nm/ TPBi 20 nm/ LiF 1 nm/ Al 200 nm. External quantum efficiencies and CIE values of 5P-VA, 5P-VTPA, and 5P-DVTPA were 1.89%, 3.59%, 3.34%, and (0.154, 0.196), (0.150, 0.076), (0.148, 0.120), respectively. 5P-VTPA and 5P-DVTPA exhibited superior highly blue quality and thermal property such as high Td of 448°C and 449°C.

Follicular dendritic cell sarcoma: a case report and review of the literature.

Follicular dendritic cells (FDC) are non-lymphoid, non-phagocytic accessory cells of the immune system and these cells are essential for antigen presentation and regulation of the reactions in germinal centers. Follicular dendritic cell sarcoma (FDCS) is a rare neoplasm that shows a low-to-intermediate malignant potential. The most commonly involved sites are the lymph nodes, but FDCS may also occur at a variety of extranodal sites, including the oral cavity, tonsils, gastrointestinal tract and liver. We describe here a 79-year-old woman who had FDCS with extensive lymph node involvement, dry cough, and an itching sensation. The patient improved after systemic chemotherapy.

Rate and predictive factors of rebleeding with obscure-overt gastrointestinal bleeding.

BACKGROUND/AIMS: Little information is available on the rate and predictive factors of rebleeding of unknown cause, which is very important in deciding further investigations on obscure-overt gastrointestinal bleeding. The aim of this study was to evaluate the rebleeding rate and related factors in obscure-overt gastrointestinal bleeding patients who revealed normal gastroscopic and colonoscopic findings. METHODS: A total of 69 patients with negative first-line gastroscopy and colonoscopy were enrolled in this study as obscure-overt gastrointestinal bleeding cases. The relationships between rebleeding and clinical characteristics were analyzed retrospectively. RESULTS: The causes of obscure-overt gastrointestinal bleeding were confirmed in 30 cases among the 69 cases. Small bowel tumors (14 cases) were the most common cause, followed by vascular lesions (6 cases). The mean follow-up period was 28 months and rebleeding was noticed in 19 patients (27.5%). Among these rebleeding patients, 14 cases (73.7%) occurred within 6 months. The past experience of previous bleeding was significantly related with rebleeding (p=0.0009). CONCLUSIONS: Close observation and detailed investigations are needed for obscure-overt gastrointestinal bleeding patients with bleeding history, especially during 6 months follow-up.