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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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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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Mechanical characterization and pH response of fibril-reinforced microcapsules prepared by layer-by-layer adsorption 总被引:3,自引:0,他引:3
Rossier-Miranda FJ Schroën K Boom R 《Langmuir : the ACS journal of surfaces and colloids》2010,26(24):19106-19113
Despite the fair number of microencapsulation principles that have been developed, the actual protection and targeted delivery of sensitive ingredients remains a challenge in the food industry. A suitable technique should use food-grade and inexpensive materials, and ensure tight control over the capsule size and release trigger mechanism. For example, encapsulates may need to survive the low pH of the stomach to release their contents in the neutral environment of the small intestine. In this work we present layer-by-layer (LbL) microcapsules assembled from whey protein isolate (WPI), high-methoxyl pectin (HMP) and WPI-fibrils. The narrow size distribution of these capsules is determined by the oil-in-water droplets used as templates, and their mechanical properties and pH response can be tuned by the number of layers adsorbed. Capsules with more than eight layers have a mechanical strength comparable to chemically cross-linked polymer capsules, because of the reinforcement by the WPI-fibrils in combination with the shell completion. Typically, capsules with five layers survive pH 2 for more than 2 h, but dissolve within 30 min at pH 7. At higher number of layers, the capsules are even more stable. Contrary to other encapsulates, these capsules can be dried and are suitable for application in dry products. 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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