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CV Tomy D Pal SS Banerjee S Ramakrishnan AK Grover S Bhattacharya MJ Higgins G Balakrishnan McK Paul 《Pramana》2002,58(5-6):925-935
The weakly pinned single crystals of the hexagonal 2H-NbSe2 compound have emerged as prototypes for determining and characterizing the phase boundaries of the possible order-disorder
transformations in the vortex matter. We present here a status report based on the ac and dc magnetization measurements of
the peak effect phenomenon in three crystals of 2H-NbSe2, in which the critical current densities vary over two orders of magnitude. We sketch the generic vortex phase diagram of
a weakly pinned superconductor, which also utilizes theoretical proposals. We also establish the connection between the metastability
effects and pinning. 相似文献
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Alberti G Brunet E Dionigi C Juanes O de La Mata MJ Rodríguez-Ubis JC Vivani R 《Angewandte Chemie (International ed. in English)》1999,38(22):3351-3353
The hydrophilic oxygen atoms of polyethylenoxide chains inserted as pillars in gamma-zirconium phosphate form hydrogen bonds with the acid groups of the host. As a result the pillars are almost perpendicular to the gamma layers. Upon changing the pH level of the supernatant solution the hydrogen bonds are broken and the pillars become almost perpendicular to the layers (shown schematically). Thus there is a reversible enlargement-shortening of the interlayer space. 相似文献
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A. R.?Milosavljevic A.?Giuliani D.?Sevic M.-J.?Hubin-Franskin B. P.?MarinkovicEmail author 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2005,35(2):411-416
Absolute differential cross-sections (DCSs) for elastic
scattering of electrons from the DNA backbone sugarlike analogue
tetrahydrofuran (THF) molecule were determined using a crossed
beam measurements for incident energies from 20 eV to 300 eV and
scattering angles from 10o to 110o. Using the
relative-flow technique, elastic DCSs for THF relative to nitrogen
have been obtained at incident energies of 20, 30, 40, 50 and 60 eV. In the energy region above 30 eV, the DCSs were measured
independently as a function of both incident electron energy and
scattering angle. Therefore, this set of relative DCSs has been
calibrated to the absolute scale via normalization to a single
point in the overlapping region. Additionally, both vibrational
and electronic energy loss spectra for THF are presented and
influence of energy resolution to the obtained DCSs is discussed. 相似文献
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M.-J. Hubin-Franskin J.E. Collin 《Journal of Electron Spectroscopy and Related Phenomena》1975,7(2):139-149
The threshold energy electron impact excitation spectra of CO2 and CS2 have been studied using the sulfur hexafluoride scavenger technique. The main results are triplet state excitation and autoionisation of negative ions associated with resonant excited states of the molecules. This confirms previous data concerning diatomic molecules. Furthermore, transitions such as 1Πg?X1Σg+ and 1Πu?X 1Σg+ are only weakly induced by low energy electrons, while the corresponding triplet excitations are probably more easily produced. Structures at 5.6, 6.1 and 6.6 eV observed in CS2 are due to negative ions and/or to 3Πu, 3Πg excitation.The autoionisation of CO2?(X2Πu) proceeds also by ejection of a thermal energy electron and leads to highly excited vibrational levels (3–5 eV) of the ground electronic state of CO2. 相似文献
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J.P. Delwiche M-Th. Praet G. Caprace M-J. Hubin-Franskin P. Natalis J.E. Collin 《Journal of Electron Spectroscopy and Related Phenomena》1977,12(4):395-403
The He(I) photoelectron spectra of perfluoro-2-butyne and perfluorohexa-2,4-diyne are reported and discussed in comparison with the photoelectron spectra of 2-butyne and hexa-2,4-diyne. Large π shifts (ca. 2 eV) towards higher ionization energies are observed as a consequence of complete substitution of hydrogen by fluorine. EXTHUC and CNDO/S calculations are found to be in good agreement with the experimental data. A new vibrational analysis of the first band of the perfluoro-2-butyne is proposed. 相似文献
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MJ Briones R Bol D Sleep L Sampedro D Allen 《Rapid communications in mass spectrometry : RCM》1999,13(13):1300-1304
Changes in the specific diet of earthworms with time in relation to landuse changes and two different climates were studied by analysing (13)C and (15)N natural abundance in soils and animals. Soil samples from three depths (0-10, 10-20 and 20-30 cm) and earthworms were collected from two sites: Santiago (Northwest Spain) and North Wyke (Southwest England) both consisting of replicated long-term grasslands and recently converted to maize plots. Earthworms were hand-sorted in the field at the peak of the maize growth and after harvesting at both sites. In the Spanish plots, nine and eight earthworm species, all belonging to the three ecological categories (epigeic, anecic and endogeic), were found under maize and permanent pasture, whereas at the English site five and seven different species were, respectively, identified. At both sites (13)C isotopic values of the earthworm tissues reflected changes in diet from C(3) to C(4) with epigeic and epi/anecic worms in the maize plots showing one delta unit difference in relation to the ones found in the grassland plots. Anecic worms seemed to be less responsive to landuse changes. The higher (13)C values of the Spanish soils were also reflected in the earthworm tissues when compared with the English samples. (15)N values showed no clear relationship with the cropping treatments but were clearly related to the ecological grouping, with endogeic worms reaching the highest values whereas for the epigeic and epi/anecic species the lowest values were obtained. This finding was also previously recorded by other authors1 and suggests that, in the future, stable isotope techniques could also be a useful tool in taxonomic studies. Copyright 1999 John Wiley & Sons, Ltd. 相似文献