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71.
Gribushin A Abramov V Antipov Y Baldin B Crittenden R Davis C Dauwe L Denisov S Dyshkant A Dzierba A Glebov V Goldberg H Jesik R Koreshev V Krider J Krinitsyn A Li R Margulies S Marshall T Martin J Mendez H Petrukhin A Solomon J Sirotenko V Smith P Sulanke T Sulyaev R Vaca F Zieminski A Blusk S Bromberg C Chang P Choudhary B Chung WH de Barbaro L Dlugosz W Dunlea J Engels E Fanourakis G Ginther G Hartman K Huston J Kapoor V Lirakis C Mani S Mansour J Maul A Miller R Oh BY Pothier E Roser R 《Physical review D: Particles and fields》1996,53(9):4723-4733
72.
73.
Alejandra Gmez‐Torres Ronda Esper Paul W. Dunk Roser Morales‐Martínez Antonio Rodríguez‐Fortea Luis Echegoyen Josep M. Poblet 《Helvetica chimica acta》2019,102(5)
The tetravalently stabilized fullerene cage of C28 is historically the most elusive small fullerene cage observed by employing the laser vaporization synthesis methodology. Its first observation reported by Smalley et al. in 1992 suggests that C28 is potentially the smallest and most stable fullerene ever observed. By using the Krätschmer?Huffman arc discharge synthesis method, we have recently succeeded in synthesizing a series of uranium‐endohedral fullerenes which differ from those reported by Smalley and co‐workers. Intrigued by this interesting mismatch, we tuned our experimental conditions to favor the formation and detection of these missing species. Experiments done using solvents of varying polarity allowed the observation of several empty and uranofullerenes. Extractions with pyridine and o‐DCB allowed for observation of small U@C2n (2n=28, 60, 66, 68, 70) by high resolution Fourier‐Transform Ion Cyclotron Resonance Mass Spectrometry (FT‐ICR MS). This is the first time that U@C28 is observed in soot produced by the Krätschmer‐Huffman arc‐discharge methodology. Carbon cage selection and spin density distribution on the endohedral metallofullerenes (EMFs) U@C60, U@C70, and U@C72 were studied by means of density functional theory (DFT) calculations. A plausible pathway for the formation of U@D3h‐C74 from U@D5h‐C70 through two C2 insertions and one Stone‐Wales rearrangement is proposed. 相似文献
74.
Triacetic acid lactone methyl ether, 4, can be lithiated at C-3 under kinetically controlled conditions. Further reaction with (E)-2-methyl-3-(4-nitrophenyl)propenal results in an unusual condensation at C-3. 相似文献
75.
P. De March J. L. Roca M. Moreno-Mañas R. Pleixats 《Journal of heterocyclic chemistry》1984,21(5):1369-1370
4-Hydroxy-6-methyl-2-pyrone (triacetic acid lactone) reacts at C-3 with acetone, mesityl oxide and pentane-2,4-dione. The structures of the final products have been elucidated. 相似文献
76.
Bai M Allgower C Ahrens L Alessi J Brown K Bunce G Cameron P Chu CM Courant ED Glenn JW Huang H Jeon D Kponou AE Krueger K Luccio A Makdisi YI Lee SY Ratner L Reece K Roser T Spinka H Syphers MJ Tsoupas N Underwood DG van Asselt W Williams N 《Physical review letters》2000,84(6):1184-1187
A new type of spin depolarization resonance has been observed at the Brookhaven Alternating Gradient Synchrotron (AGS). This spin resonance is identified as a strong closed-orbit sideband around the dominant intrinsic spin resonance. The strength of the resonance was proportional to the 9th harmonic component of the horizontal closed orbit and proportional to the vertical betatron oscillation amplitude. This "hybrid" spin resonance cannot be overcome by the partial snake at the AGS, but it can be corrected by the harmonic orbit correctors. 相似文献
77.
W. Roser 《欧洲无机化学杂志》1884,17(2):2619-2622
78.
Hojjatie MM Abrams DE Parham TM Balthrop J Beine R Dickinson V Hartshorn J Herald S Latimer G Padmore J Pleasants S Riter K Roser R Schmunck G Sensmeier R Smith V Taylor L Volgas G 《Journal of AOAC International》2004,87(2):346-351
Water soluble urea-formaldehyde (UF) fertilizers, manufactured by complex reaction of urea and formaldehyde, typically contain varying amounts of unreacted urea. A liquid chromatography method for the analysis of urea in these products, and in aqueous urea solutions, was collaboratively studied. An amine chromatography column was used to separate the unreacted urea from numerous UF reaction products present in these liquid fertilizers. Unreacted urea was determined by using external urea standards with UV detection at 195 nm. The standards and test samples were prepared in the mobile phase of 85% (v/v) acetonitrile in water. Ten laboratories analyzed 5 different UF-based commercial products containing unreacted urea in the range of 6 to 17% by weight, and 5 different concentrations of urea in water equivalent to commercial products of that nature. The aqueous urea solutions contained 2-20% urea (w/w). The range of s(R) values for the 5 UF-based commercial fertilizers was 0.49-1.02 and the %RSD(R) was 1.94-6.14. The s(R) range for the 5 urea solutions was 0.10 to 0.79 and the %RSD(R) range was 2.54 to 4.88. The average recovery of urea from the aqueous urea solutions was 96-103%. Therefore, this method is capable of monitoring urea nitrogen manufacturers' label claims and total nitrogen claims in those cases where urea is the sole source of plant food nitrogen. Based on the collaborative study data, the authors recommend this method be approved for AOAC Official First Action status. 相似文献
79.
A survey is reported on the use of additives in organic elemental analysis of compounds containing functional groups that
may compromise the combustion process. 28 substances containing the following functional groups were selected: organic fluorine,
hexafluorophosphate, tetrafluoroborate, tetraphenylborate, sulfonate, phosphine, nitrile, carbide, organometallic. Six additives
(powdered silver, silver tungstate with magnesium oxide, silica oxide, tungsten (VI) oxide with magnesium oxide, powdered
tin, cerium (IV) oxide) in various sample:additive ratios were assayed. Silver tungstate with magnesium oxide (mixture 1:1,
w/w) turned out to be most efficient for the analysis of nitrogen, carbon, hydrogen and sulfur for almost all the compounds
assayed.
Author for correspondence.
Received August 2, 2002; accepted December 12, 2002
Published online May 19, 2003 相似文献
80.
Bai M Roser T Ahrens L Alekseev IG Alessi J Beebe-Wang J Blaskiewicz M Bravar A Brennan JM Bruno D Bunce G Courant E Drees A Fischer W Gardner C Gill R Glenn J Haeberli W Huang H Jinnouchi O Kewisch J Luccio A Luo Y Nakagawa I Okada H Pilat F Mackay WW Makdisi Y Montag C Ptitsyn V Satogata T Stephenson E Svirida D Tepikian S Trbojevic D Tsoupas N Wise T Zelenski A Zeno K Zhang SY 《Physical review letters》2006,96(17):174801
The Brookhaven Relativistic Heavy Ion Collider (RHIC) has been providing collisions of polarized protons at a beam energy of 100 GeV since 2001. Equipped with two full Siberian snakes in each ring, polarization is preserved during acceleration from injection to 100 GeV. However, the intrinsic spin resonances beyond 100 GeV are about a factor of 2 stronger than those below 100 GeV making it important to examine the impact of these strong intrinsic spin resonances on polarization survival and the tolerance for vertical orbit distortions. Polarized protons were first accelerated to the record energy of 205 GeV in RHIC with a significant polarization measured at top energy in 2005. This Letter presents the results and discusses the sensitivity of the polarization survival to orbit distortions. 相似文献