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V Correcher J Garcia-Guinea FJ Valle-Fuentes 《Journal of Thermal Analysis and Calorimetry》2006,83(2):439-444
In
this paper, novel results on the blue thermally stimulated luminescence (TSL)
emission of ulexite (NaCaB5O6(OH)6·5H2O)
have been studied. The four maxima appearing at 60, 110, 200 and 240°C
on the TSL glow curves of this borate could be respectively associated to:
(i) the first dehydration (NaCaB5O6(OH)6·5H2O→NaCaB5O6(OH)6·3H2O),
(ii) the creation-annihilation of the three-hydrated
phase, (iii) the Na-coordinated chains
dehydroxylation and the starting point of the alkali self-diffusion through
the lattice and (iv) the amorphisation
of the lattice. These results are fairly well correlated with the differential
thermal analyses (DTA), in situ thermal observations under environmental scanning
electron microscope (TESEM) and thermal X-ray diffraction (TXRD) techniques. 相似文献
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Fernández-Ibáñez P de las Nieves FJ Malato S 《Journal of colloid and interface science》2000,227(2):510-516
Electron transfer between a titanium dioxide/electrolyte solution interface has been studied. As found by other researchers of similar interfaces (TiO(2)- and ZnO-electrolyte solution), a slow consumption of OH(-) ions takes place in this type of interface. A theoretical model has been developed for calculating the change in the Fermi energy of both electrolyte solution and semiconductor, showing that ion consumption from the solution is favoured by the decrease of the difference between their Fermi energies. A kinetic constant (upsilon) is found to characterise the consumption process, its value increasing with electrolyte and semiconductor mass concentrations. Furthermore, this process may be used to estimate the point of zero charge of a titanium dioxide colloidal dispersion. Copyright 2000 Academic Press. 相似文献
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van Eis MJ van Der Linde BS de Kanter FJ de Wolf WH Bickelhaupt F 《The Journal of organic chemistry》2000,65(14):4348-4354
In contrast to the terminal phosphinidene complex PhPW(CO)(5) (2), which adds to [5]metacyclophane (1) in a 1,4-fashion, dichlorocarbene preferentially adds in a 1,2-fashion to the formal "anti-Bredt" type double bond of the aromatic ring of 1 to afford the norcaradiene 11b, which immediately rearranges to the bridged cycloheptatriene 12b and further by a [1,5] sigmatropic chlorine migration to the isomeric 13b as the first observable product. More slowly, the latter isomerizes via a dissociative mechanism to give 15b. A computational study supports the notion that the [1,5] chlorine migration in the rearrangement 12b --> 13b, for which an activation barrier of 70.2 kJ mol(-)(1) was calculated, is essentially concerted with minor charge separation. In contrast, the analogous [1,5] chlorine migration in the flat model compound 7,7-dichlorocycloheptatriene (12a) displays features of a dissociative pathway. 相似文献
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J. Strömqvist L. Nardo O. Broekmans J. Kohn M. Lamperti A. Santamato M. Shalaby G. Sharma P. Di Trapani M. Bondani R. Rigler 《The European physical journal. Special topics》2011,199(1):181-194
The Biotin-Streptavidin complex is a widely studied system in biology and biophysics, because of its extremely strong non-covalent binding affinity. The latter is often exploited to link molecules to substrates or to one another. However, the details of the Biotin-Streptavidin binding have not been fully elucidated so far. Particularly, the role of cooperative effects in enhancing the binding affinity has not been clarified. Our long-term aim is to investigate this point by implementing two complementary approaches, fluorescence correlation spectroscopy and time-correlated single-photon counting. As both methods rely on the analysis of fluorescence signals, biotin labeled with Atto-550-dye was used. In this work, in order to get a first overview of the system, we analyzed solutions in three paradigmatic ranges of Biotin-to-Streptavidin concentration ratio. Fluorescence correlation spectroscopy measurements allowed us to extract diffusion times of free biotin and of biotin-Streptavidin complexes, and also to gain information about the dynamics of the intersystem crossing between the first excited triplet and the first excited singlet states. Time-correlated single-photon counting made it possible to derive the lifetimes of the different species in solution, as well as to deduce relevant information about the relative abundance of Streptavidin-complexed and free Biotin. 相似文献
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