ELO2 and ELO3 were identified from the Saccharomyces cerevisiae genome data base as homologues of ELO1, a gene involved in the elongation of the fatty acid 14:0 to 16:0. Mutations in these genes have previously been shown to produce pleiotropic effects involving a number of membrane functions. The simultaneous disruption of ELO2 and ELO3 has also been shown to produce synthetic lethality, indicating that they have related and/or overlapping functions. Gas chromatography and gas chromatography/mass spectroscopy analyses reveal that null mutations of ELO2 and ELO3 produce defects in the formation of very long chain fatty acids. Analysis of the null mutants indicates that these genes encode components of the membrane-bound fatty acid elongation systems that produce the 26-carbon very long chain fatty acids that are precursors for ceramide and sphingolipids. Elo2p appears to be involved in the elongation of fatty acids up to 24 carbons. It appears to have the highest affinity for substrates with chain lengths less than 22 carbons. Elo3p apparently has a broader substrate specificity and is essential for the conversion of 24-carbon acids to 26-carbon species. Disruption of either gene reduces cellular sphingolipid levels and results in the accumulation of the long chain base, phytosphingosine. Null mutations in ELO3 result in accumulation of labeled precursors into inositol phosphoceramide, with little labeling in the more complex mannosylated sphingolipids, whereas disruption of ELO2 results in reduced levels of all sphingolipids.In the yeast Saccharomyces cerevisiae, sphingolipids comprise approximately 10% of the total membrane lipid species (1). The hydrophobic moiety of these lipids is ceramide, which consists of a long chain base coupled to a very long chain fatty acid that is almost exclusively 26:0 1 or hydroxy 26:0 (2). Although sphingolipids are relatively minor membrane lipid species, they are highly concentrated on the plasma membrane and appear to be essential for a number of critical membrane and cellular functions (3-5). Inhibition of sphingolipid biosynthesis results in growth inhibition and cell death (6, 7). Ceramide has also been implicated as a component of an essential cell signaling pathways in Saccharomyces (8).In wild type cells, most fatty acids are 12-18-carbon species that are found in glycerolipids. Those species appear to be formed de novo by the well characterized soluble cytoplasmic fatty acid synthase complex. The very long chain (20ϩ carbon) fatty acids found in sphingolipids, however, are formed by membrane-bound fatty acid elongation systems that are not well characterized. These enzyme systems extend 14 -18-carbon fatty acids by 2-carbon units by a sequence of reactions similar to those catalyzed by fatty acid synthases, with the exception of one reduction step, which in mammalian cells appears to be mediated by cytochrome b 5 (9).We recently identified a gene (ELO1) that encodes a membrane protein involved in the elongation of 14:0 to 16:0 (10). Comparison of the amino acid sequen...

Organic light-emitting diodes (OLEDs) are increasingly used in displays replacing traditional flat panel displays; e.g., liquid crystal displays. Especially, the paradigm shifts in displays from rigid to flexible types accelerated the market change from liquid crystal displays to OLEDs. However, some critical issues must be resolved for expansion of OLED use, of which blue device performance is one of the most important. Therefore, recent OLED material development has focused on the design, synthesis and application of highefficiency and long-life blue emitters. Well-known blue fluorescent emitters have been modified to improve their efficiency and lifetime, and blue phosphorescent emitters are being investigated to overcome the lifetime issue. Recently, thermally activated delayed fluorescent emitters have received attention due to the potential of high-efficiency and long-living emitters. Therefore, it is timely to review the recent progress and future prospects of high-efficiency blue emitters. In this feature article, we summarize recent developments in blue fluorescent, phosphorescent and thermally activated delayed fluorescent emitters, and suggest key issues for each emitter and future development strategies.

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The characterization and quantification of anthocyanins in grape cultivars of Oll‐Meoru (Vitis coignetiae×Vitis labrusca), Neut‐Meoru (Vitis coignetiae×Vitis labrusca), Muscal Bailey A. (Vitis labruscana), and Campbell Early (Vitis labrusca×V. vinifera) cultivated in Korea were carried out by partial purification through XAD‐7 column chromatography followed by C‐18 HPLC/diode array detector (DAD), HPLC/MS, and HPLC/MS/MS analyses. The column oven temperature during the reverse phase C‐18 HPLC greatly affected the separation of individual anthocyanins. The result showed that the optimum column oven temperature was 35 °C. Sixteen different anthocyanins (11 nonacylated and 5 acylated anthocyanins) were identified in the grape juices. Oll‐Meoru, Neut‐Meoru, and Muscat Bailey A (MBA) grape juices contained only nonacylated anthocyanins. Oll‐Meoru and Neut‐Meoru grape juices had same anthocyanins, but their proportions were considerably different. Peonidin 3,5‐diglucoside and malvidin 3,5‐diglucoside were the major anthocyanins in Oll‐Meoru grape juice. Delphinidin 3‐glucoside was, however, the major anthocyanin in Neut‐Meoru grape juice. Peonidin 3‐glucoside and malvidin 3‐glucoside were the most abundant anthocyanins in Muscal Bailey A grape juice. Campbell Early grape juice contained both nonacylated and acylated anthocyanins. Cyanidin 3‐(p‐coumaroyl)glucoside‐5‐glucoside and peonidin 3‐(p‐coumaroyl)glucoside‐5‐glucoside were the most abundant anthocyanins in Campbell Early grape juice. Total anthocyanin contents were greatly different in different grape jucies, with the highest in Neut‐Meoru juice (1043.5 μg/mL), followed by Oll‐Meoru (997.7 μg/mL), MBA (390.2 μg/mL), and Campbell Early (183.9 μg/mL) juices. The total anthocyanin content in Neut‐Meoru grape juice was 5.67 times higher than that in Campbell Early grape juice. This represents the 1st report on the systematic characterization and quantification of anthocyanins in the juices of these grapes cultivated in Korea.

This study shows a molecular design strategy for controlling the dihedral angle of two carbazole donors linked to a 2,4-diphenyl-1,3,5-triazine acceptor by a phenyl unit. Using this approach, six thermally-activated delayed fluorescence emitters were synthesised with donors placed in various positions around a central phenyl core and the photophysical relationship between the donor position and its dihedral angle was investigated. We demonstrate that this angle can affect both the strength of the charge transfer state and the conjugation across the entire molecule, effectively changing the singlet-triplet energy gap of the system. We conclude that materials containing two substituted-ortho donors or one-ortho and an adjacent-meta have the smallest energy gaps and the shortest delayed fluorescence lifetimes. On the other hand, emitters with no-ortho substituted donors have larger energy gaps and slow-to-negligible delayed fluorescence. When applying these materials to organic light-emitting diodes , these blue-emitting devices have a range of electrical properties, the best producing efficiencies as high as 21.8% together with high resistance to roll-off that correlate with the rISC rates obtained.