A very bright white organic light-emitting diode (OLED) was realized by using a bright blue-emitting layer, 1,7-diphenyl-4-biphenyl-3,5-dimethyl-1,7-dihydrodipyrazolo[3,4-b;4′,3′-e]pyridine (PAP-Ph), together with a 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyry)-4H-pyran (DCM)-doped Alq [tris(8-hydroxyquinolinato) aluminum (III)] layer to provide blue, red, and green emission for color mixing. By appropriately controlling the layer thickness, the white light OLED achieved good performance of 24 700 cd/m2 at 15 V, 1.93 lm/W at 6.5 V, and >300 cd/m2 at 7.7 mA/cm2. The Commission Internationale de l’Eclairage coordinates of the emitted light are quite stable at voltages from 6 to 12 V, ranging from (0.35, 0.34) to (0.34, 0.35).

Metabolite T 2 is necessary for accurate quantification of the absolute concentration of metabolites using long-echo-time (TE) acquisition schemes. However, lengthy data acquisition times pose a major challenge to mapping metabolite T 2 . In this study we used proton echo-planar spectroscopic imaging (PEPSI) at 3T to obtain fast T 2 maps of three major cerebral metabolites: N-acetyl-aspartate (NAA), creatine (Cre), and choline (Cho). We showed that PEPSI spectra matched T 2 values obtained using single-voxel spectroscopy (SVS). Data acquisition for 2D metabolite maps with a voxel volume of 0.95 ml (32 ؋ 32 image matrix) can be completed in 25 min using five TEs and eight averages. A sufficient spectral signal-to-noise ratio (SNR) for T 2 estimation was validated by high Pearson's correlation coefficients between logarithmic MR signals and TEs (R 2 ‫؍‬ 0.98, 0.97, and 0.95 for NAA, Cre, and Cho, respectively). In agreement with previous studies, we found that the T 2 values of NAA, but not Cre and Cho, were significantly different between gray matter (GM) and white matter (WM; P < 0.001). The difference between the T 2 estimates of the PEPSI and SVS scans was less than 9%. Consistent spatial distributions of T 2 were found in six healthy subjects, and disagreement among subjects was less than 10%. In summary, the PEPSI technique is a robust method to obtain fast mapping of metabolite Key words: proton echo-planar spectroscopic imaging; singlevoxel spectroscopy; T 2 relaxation time; cerebral metabolites; gray/white matter difference Estimation of the relaxation times of metabolites is necessary for accurate quantification of metabolite concentrations using long-echo-time (TE) acquisition schemes (1-3). Given the T2 relaxation time, metabolite signals acquired at different TEs can be extrapolated to obtain the signal at TE ϭ 0 and thus estimate the concentration of the metabolite (4). Differences in T2 decay are negligible only for short-TE methods (with TE below 10 ms). In several pathological conditions, such as edema and ischemic stroke (5-8), interactions between cerebral metabolites and macromolecules and proteins are known to modify the biochemical environments of the metabolites, which in turn alters the motion-sensitive T2 relaxation time. Accurate estimation of metabolite T2 is therefore especially important in clinical applications of magnetic resonance spectroscopy (MRS) to ascertain whether changes in metabolite MR signals are derived from fluctuations in the metabolite concentration or from changes in the metabolite relaxation time (2,9). In addition to providing information about metabolite concentration, T2 values may give complementary information about metabolite behavior, as has been suggested by studies of brain tumor (9), ischemic stroke (5-7,10), virus infection (11), drug abuse (12), and other neurological disorders (13-15).The T2 relaxation times of metabolites can be measured by collecting multiple spectra over a range of TEs and then fitting the MR signals as a function of TE (1-3,5,10). Se...

[reaction: see text] An efficient synthesis of new middle-ring disubstituted pentiptycenes from pentiptycene quinone is reported. One of the substituents is a bromo, iodo, amino, nitro, cyano, or formyl group and the other is a hydroxy or alkoxy group. These disubstituted pentiptycenes are potential building blocks for constructing novel pentiptycene-incorporated systems.

Star-shaped compounds containing a triphenylamine as the central core and three diphenylthienylamines (NAr 1 Ar 2 (th): 3a, Ar 1 ) Ar 2 ) Ph; 3b, Ar 1 ) Ph and Ar 2 ) 3-tolyl; 3c, Ar 1 ) Ph and Ar 2 ) 1-naphthyl; 3d, NAr 1 Ar 2 ) carbazolyl) as the peripheral functional groups have been synthesized and characterized. These compounds exhibit four successive reversible one-electron redox processes except for 3d in which only two one-electron reversible oxidation waves are observed. The compounds 3a-d can be used as hole transport materials, and electroluminescent devices ITO/3/Alq [tris(8-quinolinolato)aluminum]/Mg:Ag emit green light characteristic of Alq. The device ITO/3d/BCP (bathocuproine)/Alq/Mg:Ag is blue emitting, in which 3d is the luminophore.

Green light‐emitting 3,6‐bis(diarylamino)carbazoles (see Figure; R=H, Me, OMe) have been synthesized by palladium‐catalyzed amination of 3,6‐dibromocarbazole, it is reported. The performance of electroluminescent devices with these compounds as the hole‐transport/emitting layer is shown to rival that of standard organic light‐emitting devices.

A series of 2-(stilben-4-yl)benzoxazole derivatives (BOXSB-X) was prepared and used as a dopant in the fabrication of organic light-emitting diodes. With a device structure of ITO/ NPB/CBP/TPBI:3%BOXSB-X/TPBI/Mg:Ag, where NPB, CBP, and TPBI stand for 4,4′-bis[N-(1-naphthyl)-N-phenyl-amino]-biphenyl, 4,4′-dicarbazolyl-1,1′-biphenyl, and 2,2′,2′′-(1,3,5phenylene)tris-[1-phenyl-1H-benzimidazole], respectively, light emission from the dopant was observed under electric bias, presumably due to energy transfer between the host TPBI exciton and the dopant. Bright blue emission with a luminance ranging between 8 000 and 13 000 cd/m 2 was obtained depending on the substituent on the stilbene moiety. However, with a device structure of ITO/NPB/TPBI:3%BOXSB-X/TPBI/Mg:Ag, where no CBP layer was present, the recombination/emission region shifted to the NPB layer except in the device doped with dimethylamino-substituted benzoxazole derivative, in which case the carrier trap mechanism is suggested to be responsible for the emission from the dopant.

BACKGROUND AND PURPOSE:Abscesses caused by aerobic bacteria (aerobic abscesses) can simulate intracranial glioblastomas multiforme (GBMs) in MR imaging appearance and single voxel (SV) proton MR spectroscopy of the central cavity. The purpose of our study was to determine whether MR spectroscopic imaging (SI) can be used to differentiate aerobic abscesses from GBMs. Our hypothesis was that metabolite levels of choline (Cho) are decreased in the ring-enhancing portion of abscesses compared with GBMs.

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