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961.
Mitsunori Oda Kazutaka Ogura Sayaka Kishi Kunihide Fujimori Noritaka Abe 《Tetrahedron letters》2007,48(26):4471-4475
The title azaazulene 3 was synthesized either by reaction of tropone with N-{(2-pyridyl)acetyl}pyridinium iodide in the presence of ammonium acetate or by palladium-catalyzed cross-coupling between 2-halo-1-azaazulene and 2-substituted pyridine. The compound shows relatively stronger basicity compared with 2,2′-bipyridyl. While 3 showed no emission from the S1 state but from the S2 state like azulene does, the protonated species of 3 exhibited emission from the S1 state. Cationic metal-dependent absorption and emission relating to complexation were also studied. 相似文献
962.
Minoru Maehara Koshi Ikeda Hiroaki Kurokawa Naoto Ohmura Shigeki Ikeda Yuzo Hirokawa Saori Maehara Keita Utsunomiya Noboru Tanigawa Satoshi Sawada 《Magnetic resonance imaging》2014
Purpose
To investigate whether image quality can be improved using liquid perfluorocarbon pads (Sat Pad) and clarify the optimal fat-suppression method among chemical shift selective (CHESS), water excitation (WEX), and short TI inversion recovery (STIR) methods in diffusion-weighted imaging (DWI) of the head and neck using 3-T magnetic resonance imaging. Correlations between results of visual inspection and quantitative analysis were also examined.Material and Methods
This study was approved by our Institutional Review Board and informed consent was waived. DWI was performed on 25 subjects with/without Sat Pad and using three fat-suppression methods (6 patterns). Image quality was evaluated visually (4-point scales and lesion-depiction capability) and by quantitative analysis (signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR)). Two-way repeated-measures analysis of variance (ANOVA) was used to detect significant differences in scores of visual evaluation, SNR, and CNR.Results
Mean visual evaluation scores were significantly higher with Sat Pad using STIR than without Sat Pad for all fat-suppression methods (P < 0.05). DWI with Sat Pad using STIR tended to be useful for depicting lesions. DWI using STIR showed reduced W-SNR (W: whole area of depicted structure) and CNR (between semispinalis capitis muscle and subcutaneous fat) due to fewer artifacts and uniform fat suppression.Conclusion
Combining Sat Pad with STIR provides good image quality for visual inspections. When numerous artifacts are present and fat suppression is insufficient, higher SNR and CNR do not always provide good diagnostic image quality. 相似文献963.
J. Murata H. Baba J. A. Behr Y. Hirayama T. Iguri M. Ikeda T. Kato H. Kawamura R. Kishi C. D. P. Levy Y. Nakaya K. Ninomiya N. Ogawa J. Onishi R. Openshaw M. Pearson E. Seitaibashi S. Tanaka R. Tanuma Y. Totsuka T. Toyoda 《Hyperfine Interactions》2014,225(1-3):193-196
The MTV (Mott Polarimetry for T-Violation Experiment) experiment at TRIUMF-ISAC (Isotope Separator and ACcelerator), which aims to achieve the highest precision test of time reversal symmetry in polarized nuclear beta decay by measuring a triple correlation (R-correlation), is motivated by the search for a new physics beyond the Standard Model. In this experiment, the existence of non-zero transverse electron polarization is examined utilizing the analyzing power of Mott scattering from a thin metal foil. Backward scattering electron tracks are measured using a multi-wire drift chamber for the first time. The MTV experiment was commissioned at ISAC in 2009 using an 80 % polarized 8Li beam at 107 pps, resulting in 0.1 % statistical precision on the R-parameter in the first physics run performed in 2010. Next generation cylindrical drift chamber (CDC) is now being installed for the future run. 相似文献
964.
A kind of high-repetition-rate distributed Brillouin sensor is proposed and experimentally demonstrated based on optical correlation-domain analysis with differential frequency modulation, where the optical frequencies of the pump and the probe waves are modulated at slightly different RFs so that the temporal position of the measurement is continuously and repeatedly swept along a fiber under test. A distribution map of Brillouin frequency variation along a 100 m optical fiber is acquired at a repetition rate of 20 Hz with an accuracy of ±2.5 MHz and a spatial resolution of about 80 cm. 相似文献
965.
Yamada I Yamashita N Tani K Einishi T Saito M Fukumi K Nishii J 《Optics letters》2011,36(19):3882-3884
A mid-IR wire-grid polarizer with a 500 nm pitch was fabricated on a low toxic chalcogenide glass (Sb-Ge-Sn-S system) by the thermal imprinting of periodic grating followed by the thermal evaporation of Al metal. After imprinting, deposition of Al on the grating at an oblique angle produced a wire-grid polarizer. The fabricated polarizer showed polarization with TM transmittance greater than 60% at 5-9 μm wavelengths and an extinction ratio greater than 20 dB at 3.5-11 μm wavelengths. This polarizer with a high extinction ratio can be fabricated more simply and less expensively than conventional IR polarizers. 相似文献
966.
967.
We consider a random ball-bin model where balls are thrown randomly and sequentially into a set of bins. The frequency of
choices of bins follows the Zipf-type (power-law) distribution; that is, the probability with which a ball enters the ith most popular bin is asymptotically proportional to 1/i
α
, α > 0. In this model, we derive the limiting size index distributions to which the empirical distributions of size indices
converge almost surely, where the size index of degree k at time t represents the number of bins containing exactly k balls at t. While earlier studies have only treated the case where the power α of the Zipf-type distribution is greater than unity, we here consider the case of α ≤ 1 as well as α > 1. We first investigate the limiting size index distributions for the independent throw models and then extend the derived
results to a case where bins are chosen dependently. Simulation experiments demonstrate not only that our analysis is valid
but also that the derived limiting distributions well approximate the empirical size index distributions in a relatively short
period. 相似文献
968.
Asymmetric alkynylation of aldehydes with propiolates without high reagent loading and any additives
The asymmetric alkynylation of aliphatic and aromatic aldehydes with propiolates was mediated by dialkylzinc and a novel prolinol catalyst without high reagent loading and any additives, such as Ti(Oi-Pr)(4), to give the corresponding γ-hydroxy-α,β-acetylenic esters with high enantiomeric excess of up to 95%. 相似文献
969.
A first total synthesis of broussonetine F from diethyl L-tartrate was achieved. The cornerstone of our synthesis was an orthoamide Overman rearrangement, which provided an allylic amino alcohol with complete diastereoselectivity. 相似文献
970.
Green tea (Camellia sinensis) leaves are known to contain active ingredients such as catechins and caffeine, and are widely useful materials. Recently, green tea flowers also have been in the spotlight. However, little attention has been paid to the tea seeds. In this work, the constituents of green tea seeds and green tea leaves were compared. Caffeine was found in the seeds, whereas catechins (usually obtained from green tea leaves) were not observed. Next, we investigated the constituents of hexane extracts and methanol extracts of green tea seeds. We found that the hexane extracts contained high amounts of oleic glyceride (79.9%) in addition to linoleic glyceride (20%). We confirmed the structures of these glycerides by NMR spectroscopy and by synthesis from a fatty acid and glycerol. The methanol extract was found to contain naringenin glucosides by mass spectrometry and NMR spectroscopic analysis. 相似文献