We prepared dendrimers of heteroleptic iridium(III) complexes, [(dfppy–Cz1)2Ir(dpq)]+ (G1) and [(dfppy–Cz2)2Ir(dpq)]+ (G2), which have the dfppy ligand connected to carbazole-functionalized dendron Cz n (n = 1, 2) [dfppy–Cz n = 5-Cz n -2-(4,6-difluorophenyl)pyridine, dpq = 2,3-bis-(2-pyridyl)-qinoxaline, Cz1 = 4-(9-carbazolyl)benzyloxymethyl, and Cz2 = 4-[1,3-bis(9-carbazolyl)benzyloxy]benzyloxymethyl]. While parent complex [(dfppy)2Ir(dpq)]+ (G0) shows an intense emission at ∼635 nm with a lifetime of 1 μs assigned to dpq-based metal-to-ligand charge-transfer (MLCT) phosphorescence, excitation of the dendrimers at either carbazole (309 nm) or MLCT band (355 nm) resulted in markedly weaker and much shorter-lived MLCT emission (τp = 44 ns for G1 and 115 ns for G2) at room temperature. Upon exciting the carbazole chromophore of G1 and G2 at 309 nm, furthermore, both the carbazole fluorescence and the MLCT emission were very weak at room temperature. It was found that the lifetime of carbazole fluorescence is 20 ps for G1 and 62 ps for G2, shorter by 2-orders of magnitude than that of free carbazole dendron Cz n ′–OH (τF = 6.1 ns). These observations demonstrate that both the excited-singlet state of carbazole and the triplet MLCT state of the Ir(dpq) core are efficiently quenched in the dendrimers. At 77 K, however, the MLCT emission lifetime for both G1 and G2 is ∼7 μs that is nearly identical to that of G0 (6.8 μs), and the carbazole fluorescence lifetime is ∼11.5 ± 0.5 ns, which is again almost the same as that of Cz n ′–OH (11.5 ns). Since the apparent quenching of either carbazole fluorescence or MLCT emission observed at room temperature does not occur at 77 K, the temperature-dependent emission behavior of G1 and G2 for both the carbazole fluorescence and the MLCT phosphorescence was attributed to the participation of activated processes, that is, electron transfer from excited-singlet carbazole to the Ir(dpq) core as well as from the ground-state carbazole unit to the triplet MLCT Ir(dpq) core. This mechanism was supported by transient-absorption spectroscopic experiments that demonstrate the generation of the carbazole radical cation after exciting G1 and G2 by laser pulses.

The Co oxide microfibers were synthesized using the electrospinning process and formed Co 3 O 4 microfibers after being calcined at high temperatures. The calcination temperature influenced the diameters, morphology, crystalline phase, and chemical environment of the fibers. The surface morphology of the obtained fibers was examined by using the scanning electron microscope (SEM). As the calcination temperatures increased from room temperature to 873 and 1173 K, the diameters of the cobalt oxide fibers decreased from 1.79 to 0.82 and 0.32 mm, respectively. The structure of the fibers was investigated with X-ray diffraction (XRD) and transmission electron microscopy (TEM). The calcined Co 3 O 4 fibers had crystalline face-centered cubic (fcc) structure. The X-ray photoelectron spectroscopy (XPS) results revealed that increasing the calcination temperature promoted the formation of Co 2+ and Co 3+ species.

ObjectiveTo evaluate the performance of Momguard, non-invasive prenatal test (NIPT) for detecting trisomy (T) 21, T18, T13, and sex-chromosome abnormalities recently developed in Korea. MethodsThis preliminary study formed part of a large prospective cohort study conducted at Asan Medical Center, Seoul, Korea. Only pregnant women who underwent both NIPT and confirmatory karyotyping were included in this study. NIPT results were compared with those of karyotype analyses. ResultsAmong 93 eligible cases, NIPT results could not be obtained in one case due to a low fetal cell-free DNA fraction. Based on NIPT, eight cases of fetal aneuploidies, including T21 (n=5), T18 (n=2), and T13 (n=1), were identified. For T21 and T18, the sensitivity and specificity of NIPT were both 100%, with a false-positive and false-negative rate of 0% and a positive-predictive value of 100%. One patient classified as having intermediate risk for T13 by NIPT was confirmed to have T13 by karyotyping, and there were no false-negative cases. No cases of sex-chromosome anomalies were detected by NIPT or karyotyping during the study period. ConclusionMomguard is a reliable screening tool for detecting T21 and T18. For T13 and sex-chromosome anomalies, further prospective studies are necessary to confirm its utility.