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61.
Solutions of fullerence C60 in carbon disulfide CS2 have been investigated by small-angle neutron scattering. Combination of solubility, contrast, and incoherent scattering make it possible to measure and analyze the relatively small scattering cross section of this system. Along with single fullerene molecules, a small amount of large fullerene clusters (more than 100 Å in size) is found in these solutions. The formation of these clusters depends on the procedure of solution preparation. The size distribution functions of clusters are compared with the results of the phenomenological cluster model of fullerene solubility. 相似文献
62.
S.?M.?FrolovEmail author V.?I.?Zvegintsev V.?S.?Ivanov V.?S.?Aksenov I.?O.?Shamshin D.?A.?Vnuchkov D.?G.?Nalivaichenko A.?A.?Berlin V.?M.?Fomin A.?N.?Shiplyuk N.?N.?Yakovlev 《Doklady Physical Chemistry》2018,481(1):100-103
The mode of continuous detonation combustion of hydrogen in the annular combustor of a model of a detonation air-breathing ramjet at the approach air stream Mach number 5.7 and a stagnation temperature of 1500 K was experimentally detected for the first time in a pulsed wind tunnel. The thrust and fuelbased specific impulse of the ramjet model were 1550 N and 3300 s, respectively. 相似文献
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V. L. Aksenov Yu. V. Nikitenko A. V. Petrenko V. M. Uzdin Yu. N. Khaidukov H. Zabel 《Crystallography Reports》2007,52(3):381-386
The magnetic state of the V(39 nm)/20 [V(3 nm)/Fe(3 nm)] nanostructure has been investigated by polarized neutron reflectometry in the temperature range from 1.6 to 30 K in magnetic fields from 0.2 to 15 kOe. The data obtained indicate that the superconductivity of vanadium layers may affect magnetic ordering both over the depth of the structure and in its plane. 相似文献
65.
The analysis of polystyrene and polystyrene aggregates into the mega dalton mass range by cryodetection MALDI TOF MS 总被引:1,自引:0,他引:1
Mass spectra of atactic polystyrene were collected into the mega-dalton mass range with a matrix-assisted laser desorption ionization time of flight (MALDI TOF) mass spectrometer, which incorporates a cryodetector comprised of an array of 16 superconducting tunnel junctions (STJ). The STJ cryodetector, theoretically, has no loss in signal response at any mass compared with the reduced signal found at high mass when using a conventional secondary-ionization detector. Since ion detection at high m/z is one of the fundamental limitations of mass spectrometry (MS), the cryodetector was used to explore the high m/z limit of the MALDI TOF technique for the analysis of two polymer types. Mass spectra were collected for polystyrene at Mn 170, 400, 900, and 2000 kDa and polymethyl methacrylate (PMMA) at Mn 62.6 kDa and 153.7 kDa. For polystyrene, the data showed a trend toward increased aggregation and charge state with mass. The Mn 2 MDa polystyrene data revealed a peak at m/z 2.2 MegaTh and a charge state analysis revealed that these ions were primarily polystyrene aggregates with a mass of approximately 4 MDa. This aggregate assignment was possible because the cryodetector response allows for the determination of a charge state up to about four. The contribution of each charge state for a selected peak can be determined in this fashion. This analysis revealed the preferential formation of doubly charged even-numbered aggregates over odd-numbered aggregates for high molecular mass polystyrene. A potential mechanism for the aggregation process for doubly charged species is discussed. 相似文献
66.
A method has been developed for the synthesis of 2,2′- and 3,3′-biquinolines and of 4,4′-bipyridine based on the coupling
of 2- and 3-bromoquinoline or 4-bromopyridine using a Pd/C-hydrazine-KOH catalytic system.
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1839–1840, December, 2008. 相似文献
67.
O. A. Shevlyakova K. Yu. Vasil’ev A. A. Ikhalainen A. M. Antokhin V. F. Taranchenko V. M. Goncharov D. A. Mitrofanov A. V. Aksenov I. A. Rodin O. A. Shpigun 《Journal of Analytical Chemistry》2016,71(8):768-776
Fragmentation of the main Barrenwort flavonoids—icariin, icaritin, icarisides I and II, and epimedins A and B—is studied by tandem mass spectrometry. High-resolution mass spectra of positively charged ions of these compounds are obtained under the conditions of collision-induced dissociation. Characteristic fragment ions are determined, which ensured the classification of unknown compounds as Barrenwort flavonoids. Epimedin C was isolated from raw plant material by preparative liquid chromatography; its structure was confirmed by 1H and 13C NMR spectra. 相似文献
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S. A. Karamian N. V. Aksenov Yu. A. Al’bin A. G. Belov G. A. Bozhikov S. N. Dmitriev G. Ya. Starodub 《Bulletin of the Russian Academy of Sciences: Physics》2014,78(5):367-372
Among nuclides, 195m Pt isomer is characterized by a number of properties that make it suitable for use in nuclear medicine. Effective ways of optimizing the Pt isomer yield at low impurity contents must be sought. The method based on double neutron capture by the 193Ir target nucleus with subsequent populating of 195m Pt through β decay allows chemical isolation of the isomer. In this work, the problem is analyzed, test experiments on Ir activation with neutrons are conducted, and theoretical estimates of the 195m Pt yield are presented. Full-scale model experiments on the IBR-2 reactor in Dubna should confirm the effectiveness of the method. 相似文献