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排序方式: 共有155条查询结果,搜索用时 265 毫秒
81.
A. I. Svirikhin A. V. Yeremin A. V. Andreev I. N. Izosimov A. V. Isaev A. N. Kuznetsov A. A. Kuznetsova O. N. Malyshev A. G. Popeko Y. A. Popov E. A. Sokol M. L. Chelnokov V. I. Chepigin T. M. Schneidman B. Gall O. Dorvaux P. Brione K. Hauschild A. Lopez-Martenz K. Rezynkina S. Mullins P. Jones P. Mosat B. Andel Z. Kalaninova M. Z. Asfari N. Yoshihiro J. Piot E. Stefanova D. Tonev 《Bulletin of the Russian Academy of Sciences: Physics》2018,82(6):632-636
series of experiments performed in 2014–2015 using the SHELS separator and a beam of multicharged ions from the U-400 accelerator at the Flerov Laboratory of Nuclear Reactions (Joint Institute for Nuclear Research) in Dubna is described. In preparation for a large program of experiments with a beam of highly charged ions of 50Ti, an experiment is performed to study the spontaneous fissioning (SF) of short-lived neutron-deficient isotope 256Rf formed in complete fusion reaction50Ti + 208Pb = 256Rf + 2n. The half-life of 256Rf is measured along with the probability of its SF decay. The average number of neutrons per one event of 256Rf SF (\(\bar v\)= 4.47 ± 0.09) is obtained for the first time. The results from experiments to study the SF of short-lived neutron-deficient isotopes synthesized in complete fusion reaction 48Ca + 204Pb → 252No* are presented as well. Two short-lived activities attributed to the SF of the ground and isomeric states of 250No are revealed. The half-life, total kinetic energies of fission fragments, and neutron multiplicities are measured for the obtained short-lived nuclei. The average numbers of neutrons per one SF event are \(\bar v\)= 4.38 ± 0.13 and \(\bar v\)= 3.90 ± 0.20, respectively, for SF activity with t1/2 = 5.1 ± 0.3 and t1/2 = 36 ± 3 μs. 相似文献
82.
83.
Liquid borne ultrafine particles have elsewhere been shown to pass through a packed column at rates varying with particle size. The process is termed “hydrodynamic chromatography”, since a separation of the particles according to size can thereby be achieved. Similar results are reported herein for larger particles suspended in liquid when the passageway, instead of being a packed column is a long, completely open, capillary tube. Particle transit time is a function of the logarithm of particle diameter. The underlying mechanism for the latter phenomena is believed to be that previously called the “tubular pinch effect” which arises from a balance of lateral forces within the flow field, but experimental results are not adequately described by any theory yet proposed. The open-tube discrimination process is designated “capillary hydrodynamic chromatography”. 相似文献
84.
85.
Chockla AM Harris JT Akhavan VA Bogart TD Holmberg VC Steinhagen C Mullins CB Stevenson KJ Korgel BA 《Journal of the American Chemical Society》2011,133(51):20914-20921
A nonwoven fabric with paperlike qualities composed of silicon nanowires is reported. The nanowires, made by the supercritical-fluid-liquid-solid process, are crystalline, range in diameter from 10 to 50 nm with an average length of >100 μm, and are coated with a thin chemisorbed polyphenylsilane shell. About 90% of the nanowire fabric volume is void space. Thermal annealing of the nanowire fabric in a reducing environment converts the polyphenylsilane coating to a carbonaceous layer that significantly increases the electrical conductivity of the material. This makes the nanowire fabric useful as a self-supporting, mechanically flexible, high-energy-storage anode material in a lithium ion battery. Anode capacities of more than 800 mA h g(-1) were achieved without the addition of conductive carbon or binder. 相似文献
86.
Andrews AB McClelland A Korkeila O Demidov A Krummel A Mullins OC Chen Z 《Langmuir : the ACS journal of surfaces and colloids》2011,27(10):6049-6058
Asphaltenes are an important class of compounds in crude oil whose surface activity is important for establishing reservoir rock wettability which impacts reservoir drainage. While many phenomenological interfacial studies with crude oils and asphaltenes have been reported, there is very little known about the molecular level interactions between asphaltenes and mineral surfaces. In this study, we analyze Langmuir-Blodgett films of asphaltenes and related model compounds with sum frequency generation (SFG) vibrational spectroscopy. In SFG, the polarization of the input (vis, IR) and output (SFG) beams can be varied, which allows the orientation of different functional groups at the interface to be determined. SFG clearly indicates that asphaltene polycyclic aromatic hydrocarbons (PAHs) are highly oriented in the plane of the interface and that the peripheral alkanes are transverse to the interface. In contrast, model compounds with oxygen functionality have PAHs oriented transverse to the interface. Computational quantum chemistry is used to support corresponding band assignments, enabling robust determination of functional group orientations. 相似文献
87.
N. Rowley N. Grar S. S. Ntshangase R. A. Bark S. V. Förtsch J. J. Lawrie E. A. Gueorguieva S. M. Maliage L. J. Mudau S. M. Mullins O. M. Ndwandwe R. Neveling G. Sletten F. D. Smith C. Theron 《Physics of Atomic Nuclei》2006,69(7):1093-1100
In intermediate-mass systems, collective excitations of the target and projectile can greatly enhance the subbarrier capture
cross section σ
cap by giving rise to a distribution of Coulomb barriers. For such systems, capture essentially leads directly to fusion [formation
of a compound nucleus (CN)], which then decays through the emission of light particles (neutrons, protons, and alpha particles).
Thus, the evaporation-residue (ER) cross section is essentially equal to σ
cap. For heavier systems, the experimental situation is significantly more complicated owing to the presence of quasifission
(QF) (rapid separation into two fragments before the CN is formed) and by fusion-fission (FF) of the CN itself. Thus, three
cross sections need to be measured in order to evaluate σ
cap. Although the ER essentially recoil along the beam direction, QF and FF fragments are scattered to all angles and require
the measurement of angular distributions in order to obtain the excitation function and barrier distribution for capture.
Two other approaches to this problem exist. If QF is not important, one can still measure just the ER cross section and try
to reconstruct the corresponding σ
cap through use of an evaporation-model code that takes account of the FF degree of freedom. Some earlier results on σ
cap obtained in this way will be reanalyzed with detailed coupled-channels calculations, and the “extra-push” phenomenon discussed.
One may also try to obtain σ
cap by exploiting unitarity, that is, by measuring instead the flux of particles corresponding to quasielastic (QE) scattering
from the Coulomb barrier. Some new QE results obtained for the 86Kr + 208Pb system at iThemba LABS in South Africa will be presented.
The text was submitted by the authors in English. 相似文献
88.
High-performance liquid chromatographic assay with electrochemical detection for azithromycin in serum and tissues. 总被引:7,自引:0,他引:7
High-performance liquid chromatographic methods using reversed-phase chromatography and electrochemical detection have been developed for the quantitation of azithromycin in serum and tissues of laboratory animals and humans. Serum sample preparation involved addition of internal standard, alkalinization, and solvent extraction. Tissue sample preparation involved Polytron homogenization in acetonitrile containing internal standard, evaporation of the supernatant, alkalinization of the residue, and solvent extraction. Serum samples were chromatographed on an alkylphenyl-bonded silica column eluted with pH 6.8-7.2 mobile phase with a dual-electrode coulometric detector operated in the oxidative screen mode. Serum and tissue samples were chromatographed on a gamma RP-1 alumina column with pH 11 mobile phase with a glassy carbon amperometric detector. Recovery of azithromycin was 87% from serum and 85% from tissues. Linear standard curves were prepared in serum over two concentration ranges (0.01-0.20 and 0.20-2.0 micrograms/ml) and in tissues over several concentration ranges (0.1-2, 1-10, 10-100, and 100-1000 micrograms/g). In serum and tissues, intra- and inter-assay precision ranged from 1 to 8% and 4 to 11%, respectively. The tissue assay has been applied to liver, kidney, lung, spleen, muscle, fat, brain, tonsil, lymph nodes, eye, prostate and other urological tissues, and gynecological tissues. 相似文献
89.
R. Wyss A. Johnson D. J. G. Love M. J. Godfrey S. M. Mullins 《Zeitschrift für Physik A Hadrons and Nuclei》1989,332(2):241-242
The level scheme of the yrast band of124Ba has been extended up to spin 32?. Transitions in the two negative parity side bands are observed up to spin 27? and tentatively 20?. The second backbend observed in the S-band and the backbends in the side bands are explained as due to neutrons. The structure of the sidebands is discussed and compared with deformation self-consistent calculations, Total Routhian Surfaces (TRS). 相似文献
90.
Observation and modelling of barrel droplets on vertical fibres subjected to gravitational and drag forces 总被引:1,自引:0,他引:1
Mullins BJ Braddock RD Agranovski IE Cropp RA 《Journal of colloid and interface science》2006,300(2):704-712
Extensive experimental investigation of the wetting processes of fibre/liquid systems during air filtration (when drag and gravitational forces are acting) has shown many important features, including droplet extension, oscillatory motion, and detachment or flow of drops from fibres as airflow velocity increases. A detailed experimental study of the aforementioned processes was conducted using glass filter fibres and H(2)O aerosol, which coalesce on the fibre to form barrel droplets with small contact angles. The droplets were predominantly observed in the Reynolds transition (or unsteady laminar) flow region. The droplet oscillation appears to be induced by the onset of vortexes in the flow field around the droplet as the increasing droplet size increases the Reynolds number. Flow in this region is usually modelled using the classical two-dimensional Karman vortex street, and there exist no 3D equivalents. Therefore to model such oscillation it was necessary to create a new conceptual model to account for the forces both inducing and inhibiting such oscillation. The agreement between the model and experimental results is acceptable for both the radial and transverse oscillations. 相似文献