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The photophysics and photostability of 9,10-bis(phenylethynyl)anthracene (BPEA) diluted in a 40-nm-thick Zeonex polymer film have been investigated by single-molecule spectroscopy (SMS). The single-molecule detection of BPEA was verified by recording fluorescence intensity trajectories, fluorescence lifetimes, and fluorescence spectra. The intensity trajectories showed frequent on/off blinking and one-step photobleaching behaviors. The observed blinking was attributed to the temporary occupation of the excited triplet state T 1 via intersystem crossing (ISC). Assuming a threestate model (e.g., S 0 , S 1 , and T 1 ), the distributions of triplet lifetime and S 1 AT 1 ISC quantum yield of BPEA were both derived from the analyses of the blinking statistics and the intensity autocorrelation. We found extremely low ISC yields (on the order of 10 25 -10 24 ), which were theoretically rationalized by the large energy gap between 3 B 2u and S 1 ( 1 B 1u )/T 1 ( 3 B 1u ) states. SMS measurements were also conducted under both air and Ar atmospheres in order to gain insight into the influence of oxygen on photobleaching. The results reveal that, although the presence of oxygen considerably degraded the photostability of BPEA, under deoxygenated conditions, BPEA delivers more than 10 7 photons before photobleaching and possesses an appreciably low photobleaching yield of 10 29 -10 28 . This study shows that BPEA has a relatively high degree of photostability at room temperature and can serve as a useful green fluorescent probe for SMS studies.

One of the most powerful ways of succeeding in complex social interactions is to read the minds of companions and stay a step ahead of them. In order to assess neural responses to reciprocal mind reading in socially strained human relationships, we used a 3-T scanner to perform an event-related functional magnetic resonance imaging study in 16 healthy subjects who participated in the game of Chicken. Statistical parametric mapping showed that the counterpart effect (human minus computer) exclusively activated the medial frontal area corresponding to the anterior paracingulate cortex (PCC) and the supramarginal gyrus neighboring the posterior superior temporal sulcus (STS). Furthermore, when we analyzed the data to evaluate whether the subjects made risky/aggressive or safe/reconciliatory choices, the posterior STS showed that the counterpart had a reliable effect regardless of risky or safe decisions. In contrast, a significant opponent x selection interaction was revealed in the anterior PCC. Based on our findings, it could be inferred that the posterior STS and the anterior PCC play differential roles in mentalizing; the former serves as a general mechanism for mentalizing, while the latter is exclusively involved in socially risky decisions.

Purpose To examine the diagnostic performance of high-spatial-resolution (HSR) CT with 0.25-mm section thickness for evaluating renal artery in-stent restenosis. Materials and Methods A 0.05-mm wire phantom and vessel phantoms with renal stents with in-stent stenotic sections of varying diameters were scanned with both an HSR CT scanner equipped with 160-section multi-detector rows (0.25-mm section thickness) and a conventional CT scanner. The wire phantom was used to analyze modulation transfer function (MTF). With the vessel phantoms, the error rates were calculated as the absolute difference between the measured diameters and true diameters divided by the true diameters at the narrowing sections. For qualitative evaluation, overall image quality and diagnostic accuracy for evaluating stenosis in three stages were assessed by two radiologists. Statistical analyses included the paired t test, Wilcoxon signed-rank test, and McNemar test. Results HSR CT achieved 24.3 line pairs per centimeter ± 0.5 (standard deviation) and 29.1 line pairs per centimeter ± 0.4 at 10% and 2% MTF, respectively; and conventional CT was 12.5 line pairs per centimeter ± 0.1 and 14.3 line pairs per centimeter ± 0.1 at 10% and 2% MTF, respectively. The mean error rate of the measured diameter at HSR CT (8.0% ± 5.8) was significantly lower than that at at conventional CT (16.9% ± 9.3; P < .001). Image quality at HSR CT was significantly better than that at conventional CT (P < .001), but HSR CT was not significantly superior to conventional CT in terms of diagnostic accuracy. Conclusion Compared with conventional CT, high-spatial-resolution CT achieved spatial resolutions of up to 29 line pairs per centimeter at 2% modulation transfer function and yielded improved measurement accuracy for the evaluation of in-stent restenosis in a phantom study of renal artery stents. Published under a CC BY 4.0 license.

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Tri-and tetrafunctional silyl enol ethers, Mer -,,C[CHZOC~H~C(OS~M~~)=CHZI,, (3: n = 3;4 n = 4), proved efficient multifunctional coupling agents for the living polymer of isobutyl vinyl ether (IBVE) prepared by the hydrogen chloridehinc chloride (HCl/ZnClZ) initiating system at -15 "C in methylene chloride. The silyl enol ethers were readily synthesized by the silyl enolation of the corresponding multifunctional acetophenones (e&, 6 and 8). Upon the coupling reactions, the number-average molecular weights (an) of the products increased in accordance with the multiplicity of the cou lin agents (e.g., 4-fold increase with 4), while the molecular weight distributions became even narrower (&Jh,, < 1.1) than that of the original living polymer. The products were identified by 1H NMR spectroscopy: 3 and 4 led to the tri-and tetraarmed polymers (3-P and 4-P, respectively), where the living polymer (arm) was connected to the coupling agent via an aromatic ketone linkage (CHzOC6H4COCHz-polymer). The coupling of a relatively short chain of living poly(1BVE) (G, -10) occurred nearly quantitatively to give the multiarmed polymers (yield > 95%), but the yield decreased slightly (8690%) with a longer living chain (E, -50).

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Tri- and tetraarmed polymers (3-P and 4-P) of α-methylstyrene (αMeSt) and their end-functionalized versions (12) [R4 - m C{CH2OC6H4COCH2−(αMeSt) n −CHMeOCH2CH2−X} m (Me = CH3); arm number m = 3 (R = Me), 4; X = Cl, OCOMe, OCOCMe=CH2] have been synthesized by coupling reactions of living poly(αMeSt) with multifunctional silyl enol ethers [R4 - m C{CH2OC6H4C(OSiMe3)CH2} m ; 3, m = 3, R = Me; 4, m = 4]. The living poly(αMeSt) was prepared by living cationic polymerization in methylene chloride solvent at −78 °C with the hydrogen chloride−vinyl ether adduct [Cl−CHMe(OCH2CH2−X)] as initiator in conjunction with tin tetrabromide (SnBr4). Subsequently, the living chains were allowed to react with 3 or 4 in the presence of N-ethylpiperidine to give the target multiarmed polymers in high yield (>90%). Specifically for αMeSt, it proved crucial that N-ethylpiperidine and similar nucleophiles should be added into the living polymer solution for its efficient coupling to occur. In the end-functionalized polymers (12), each of the four poly(αMeSt) arms carries a terminal function X, which would provide a novel cross-linking agent [X = OH (from OCOMe)] or a tetraarmed macromonomer (X = methacryloyl).