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321.
Jane V. Knichal Dr. Helena J. Shepherd Prof. Chick C. Wilson Prof. Paul R. Raithby Dr. William J. Gee Prof. Andrew D. Burrows 《Angewandte Chemie (International ed. in English)》2016,55(20):5943-5946
A vapor‐induced cyclization has been observed in the host environment of a crystalline molecular flask (CMF), within which 1,8‐bis(2‐phenylethynyl)naphthalene (bpen), a diarenynyl system primed for cyclization, was exposed to iodine vapor to yield the corresponding indeno[2,1‐α]phenalene species. The cyclization process, unique in its vapor‐induced, solvent‐free nature, was followed spectroscopically, and found to occur concurrently with the displacement of lattice solvent for molecular iodine in CMF?0.75 bpen?2.25 CHCl3?H2O. The cyclization occurred under mild conditions and without the need to suspend the crystals in solvent. The ability of CMFs to host purely gas‐induced reactions is further highlighted by the subsequent sequential oxidation reaction of cyclized 7‐iodo‐12‐phenylindeno[2,1‐α]phenalene (ipp) with molecular oxygen derived from air, yielding 12‐hydroxy‐7‐iodo‐2‐phenylindeno[2,1‐α]phenalen‐1(12H)‐one (hipp). 相似文献
322.
The Bingham fluid model was developed to represent viscoplastic materials that change from rigid bodies at low stress to viscous fluids at high stress – a process termed yielding. Such a fluid model is used in the modeling of slurries, which occur frequently in food processing and other engineering applications. 相似文献
323.
Peter T. Shepherd 《Trends in analytical chemistry : TRAC》1981,1(1):1-3
Izaak Maurits Kolthoff was born in 1894, in Almelo, Holland. He studied pharmacy at the University of Utrecht, and was awarded a Ph.D. in chemistry there in 1918. He served as Conservator of the Pharmaceutical Institute at the University from 1917 to 1927 and as a privat docent (lecturer) from 1924 to 1927. In 1927 Professor Kolthoff began his long association with the University of Minnesota, serving as Professor and Chief of the Division of Analytical Chemistry until 1962 and since then as Professor Emeritus. He is a member of the United States National Academy of Sciences, a foreign member of the Royal Flemish Academy of Sciences and of a number of other learned Societies thoughout the world. He has, in the course of his long career, been given many awards. The latest of these is the Special Award of the Society for Analytical Chemists of Pittsburgh for 1981. 相似文献
324.
325.
Bornheim A Lipeles E Pappas SP Weinstein AJ Briere RA Chen GP Ferguson T Tatishvili G Vogel H Watkins ME Adam NE Alexander JP Berkelman K Cassel DG Duboscq JE Ecklund KM Ehrlich R Fields L Galik RS Gibbons L Gittelman B Gray R Gray SW Hartill DL Heltsley BK Hertz D Hsu L Jones CD Kandaswamy J Kreinick DL Kuznetsov VE Mahlke-Krüger H Meyer TO Onyisi PU Patterson JR Peterson D Pivarski J Riley D Rosner JL Ryd A Sadoff AJ Schwarthoff H Shepherd MR Sun WM Thayer JG Urner D Wilksen T Weinberger M 《Physical review letters》2004,93(24):241802
We have searched a sample of 9.6 x 10(6) BB events for the lepton-flavor-violating leptonic B decays, B(0)-->mu(+/-)tau(-/+) and B(0)-->e(+/-)tau(-/+). The tau lepton was detected through the decay modes tau-->lnunu(-) , where l=e, mu. There is no indication of a signal, and we obtain the 90% confidence level upper limits B(B(0)-->mu(+/-)tau(-/+))<3.8 x 10(-5) and B(B(0)-->e(+/-)tau(-/+))<1.3 x 10(-4). 相似文献
326.
327.
Intense blue upconversion emission at 480 nm has been obtained at room temperature in Tm3+-Nd3+ co-doped Ta2O5 channel waveguides fabricated on a Si substrate, when the sample is excited with an infrared laser at 793 nm. The upconversion mechanism is based on the radiative relaxation of the Nd3+ ions (4F3/2 → 4I11/2) at about 1064 nm followed by the absorption of the emitted photons by Tm3+ ions in the 3H4 excited state. A coefficient of energy transfer rate as high as 3 × 10−16 cm3/s has been deduced using a rate equation analysis, which is the highest reported for Tm-Nd co-doped systems. The confinement of the 1064 nm emitted radiation in the waveguide structure is the main reason of the high energy transfer probability between Nd3+ and Tm3+ ions. 相似文献
328.
Athar SB Patel R Yelton J Rubin P Eisenstein BI Karliner I Mehrabyan S Lowrey N Selen M White EJ Wiss J Mitchell RE Shepherd MR Besson D Pedlar TK Cronin-Hennessy D Gao KY Hietala J Kubota Y Klein T Lang BW Poling R Scott AW Zweber P Dobbs S Metreveli Z Seth KK Tomaradze A Libby J Powell A Wilkinson G Ecklund KM Love W Savinov V Lopez A Mendez H Ramirez J Ge JY Miller DH Shipsey IP Xin B Adams GS Anderson M Cummings JP Danko I Hu D Moziak B Napolitano J He Q Insler J Muramatsu H Park CS 《Physical review letters》2008,100(18):181802
Using e+e--->Ds*-Ds+ data collected near the peak Ds production energy, Ecm=4170 MeV, with the CLEO-c detector, we present the first observation of the decay Ds+-->pn. We measure a branching fraction B(Ds+-->pn)=(1.30+/-0.36(-0.16)+0.12)x10(-3). This is the first observation of a charmed meson decaying into a baryon-antibaryon final state. 相似文献
329.
Catherine Klifa Julio Carballido-Gamio Lisa Wilmes Anne Laprie John Shepherd Jessica Gibbs Bo Fan Susan Noworolski Nola Hylton 《Magnetic resonance imaging》2010,28(1):8-15
A quantitative measure of three-dimensional breast density derived from noncontrast magnetic resonance imaging (MRI) was investigated in 35 women at high-risk for breast cancer. A semiautomatic segmentation tool was used to quantify the total volume of the breast and to separate volumes of fibroglandular and adipose tissue in noncontrast MRI data. The MRI density measure was defined as the ratio of breast fibroglandular volume over total volume of the breast. The overall correlation between MRI and mammographic density measures was R2=.67. However the MRI/mammography density correlation was higher in patients with lower breast density (R2=.73) than in patients with higher breast density (R2=.26). Women with mammographic density higher than 25% exhibited very different magnetic resonance density measures spread over a broad range of values. These results suggest that MRI may provide a volumetric measure more representative of breast composition than mammography, particularly in groups of women with dense breasts. Magnetic resonance imaging density could potentially be quantified and used for a better assessment of breast cancer risk in these populations. 相似文献
330.
We demonstrate the suitability of a simple continuous-wave-pumped transition-metal-ion-doped waveguide as a broadband light source in the wavelength region 600-1000 nm for interferometric applications. Spatially coherent (single mode in the confined direction), spectrally broadband (~130-nm FWHM) luminescence with output powers of several hundreds of microwatts is obtained from a Ti:sapphire planar waveguide with incident pump powers from an Ar-ion laser of up to 1 W. This result represents an increase in power by several orders of magnitude from previously reported simple broadband light sources in this wavelength range. 相似文献