排序方式: 共有34条查询结果,搜索用时 7 毫秒
11.
A. Kyritsis A. Spanoudaki C. Pandis L. Hartmann R. Pelster N. Shinyashiki J.C. Rodríguez Hernández J.L. Gómez Ribelles M. Monleón Pradas P. Pissis 《European Polymer Journal》2011,47(12):2391-2402
Water and polymer dynamics in hydrogels based on random copolymers of hydrophilic poly(hydroxyl ethyl acrylate) (PHEA) and hydrophobic poly(ethyl acrylate) (PEA), in wide ranges of composition, were investigated by means of two dielectric techniques, thermally stimulated depolarization currents (TSDC) and, mainly, broadband dielectric relaxation spectroscopy (DRS) at several levels of relative humidity/water content. Water sorption of the hydrogels was studied by equilibrium sorption isotherms (ESI). Two secondary relaxations (γ and βsw) and the primary (segmental) α relaxation associated with the glass transition of the copolymer matrix were followed and analyzed against copolymer composition and water content. The results show that the copolymers are homogeneous at nm scale, except at very high PEA content. Correlations were observed between results on the organization of water in the hydrogels and on water effects on polymer dynamics. Distinct changes in the dielectric response, in particular in the time scale and the dielectric strength of the βsw relaxation, at the water content of the completion of the first hydration layer indicate that water molecules themselves contribute to the dielectric response at higher water contents. Proton conductivity of the hydrogels at various levels of water content was also studied and correlation to segmental dynamics (decoupling) was analyzed. 相似文献
12.
Abstract A critical examination of the behaviour of three fragile glass forming liquids viz. Salol, α-phenyl-o-cresol and o-terphenyl, has been carried out using differential scanning calorimetry and dielectric relaxation technique (frequency: 106-10?3 Hz). Our study reveals two sub-Tg processes designated as β- and γ-processes, in addition to the primary (α-) process. The β-process has an activation energy of 36–50 kJ/mol. in these liquids, and is found to be intramolecular in nature. Our results along with the published viscosity data on these liquids indicate a decoupling of the viscous modes from the α-modes in the region of Tg, with the latter still retaining its non-Arrhenius character. The nature of this decoupling has been discussed in detail. 相似文献
13.
Bernd Aulbach 《Journal of Difference Equations and Applications》2013,19(3-4):283-296
In this paper, we continue the study of geometric properties of nonautonomous difference equations in arbitrary Banach spaces which was begun in [2,3]. Building on previous results on invariant fiber bundles and foliations, this paper addresses the problem of topological simplifications via continuous conjugacies and semiconjugacies. In particular, we establish a reduction principle for not necessarily invertible difference equations, as well as a generalized Hartman–Grobman theorem for systems with not necessarily invertible linear part. 相似文献
14.
We theoretically investigate the electronic transport through a parallel-coupled multi-quantum-dot system, in which the terminal dots of a one-dimensional quantum-dot chain are embodied in the two arms of an Aharonov–Bohm interferometer. It is found that in the structures of odd(even) dots, all their even(odd) molecular states have opportunities to decouple from the leads, and in this process antiresonance occurs which are accordant with the odd(even)-numbered eigenenergies of the sub-molecule without terminal dots. Next when Majorana zero modes are introduced to couple laterally to the terminal dots, the antiresonance and decoupling phenomena still co-exist in the quantum transport process. Such a result can be helpful in understanding the special influence of Majorana zero mode on the electronic transport through quantum-dot systems. 相似文献
15.
《Comptes Rendus Mecanique》2017,345(10):724-731
We consider an arc-shaped conducting rigid line inclusion located at the interface between a circular piezoelectric inhomogeneity and an unbounded piezoelectric matrix subjected to remote uniform anti-plane shear stresses and in-plane electric fields. Moreover, one side of the rigid line inclusion has become fully debonded from the matrix or the inhomogeneity leading to the formation of an insulating crack. After the introduction of two sectionally holomorphic vector functions, the problem is reduced to a vector Riemann–Hilbert problem, which can be decoupled sequentially by repeated application of the orthogonality relations between the eigenvectors for two corresponding generalized eigenvalue problems. 相似文献
16.
Frequency domain photon migration (FDPM) technique was employed to investigate the structure factors of dense, polydisperse colloidal suspensions. The angle-integrated structure factors, [S(q)], extracted from FDPM measurements of scattering properties at volume fractions ranging from 0.05 to 0.4, were compared with the values predicted from the polydisperse hard sphere Percus-Yevick (HSPY) model, as well as decoupling approximation (DA) and local monodisperse approximation (LMA) models that incorporated independently measured particle size information. Results show that the polydisperse HSPY model is the most suitable for accounting for particle interactions which predominantly arise from volume exclusion effects. Furthermore, the influence of size polydispersity upon [S(q)] is most significant at high volume fractions. The static structure factors at small wave vector q, S(0), were also assessed from dual wavelength FDPM measurements by using the small wave number approximation as well as the local monodisperse approximation. The measured S(0) agrees well with the values predicted by the polydisperse HSPY model. 相似文献
17.
Sinha N Grant CV Wu CH De Angelis AA Howell SC Opella SJ 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2005,177(2):197-202
Continuous wave irradiation has limited bandwidth for heteronuclear 1H decoupling at high fields and for 13C decoupling in 1H/13C/15N triple-resonance experiments. SPINAL-16 modulation is shown to improve the efficiency of 1H and 13C heteronuclear decoupling on single crystals of peptides and on magnetically aligned samples of membrane proteins in bicelles, which is of particular importance because aqueous samples of biomolecules are lossy at high fields, which limits the strengths of the RF fields that can be applied. 相似文献
18.
《Stochastic Processes and their Applications》2020,130(6):3711-3752
We deduce conditional -estimates for the variation of a solution of a BSDE. Both quadratic and sub-quadratic types of BSDEs are considered, and using the theory of weighted bounded mean oscillation we deduce new tail estimates for the solution on subintervals of . Some new results for the decoupling technique introduced in Geiss and Ylinen (2019) are obtained as well and some applications of the tail estimates are given. 相似文献
19.
Felipe W. Chaves-Silva Lionel Rosier Enrique Zuazua 《Journal de Mathématiques Pures et Appliquées》2014
In this paper, we consider the wave equation with both viscous Kelvin–Voigt and frictional damping as a model of viscoelasticity in which we incorporate an internal control with a moving support. We prove the null controllability when the control region, driven by the flow of an ODE, covers all the domain. The proof is based upon the interpretation of the system as, roughly, the coupling of a heat equation with an ordinary differential equation (ODE). The presence of the ODE for which there is no propagation along the space variable makes the controllability of the system impossible when the control is confined into a subset in space that does not move. The null controllability of the system with a moving control is established in using the observability of the adjoint system and some Carleman estimates for a coupled system of a parabolic equation and an ODE with the same singular weight, adapted to the geometry of the moving support of the control. This extends to the multi-dimensional case the results by P. Martin et al. in the one-dimensional case, employing 1-d Fourier analysis techniques. 相似文献
20.
The use of 1H NMR at low field (60 MHz spectrometer frequency) for direct analysis of mixtures of borneol, 1, and isoborneol, 2, is considerably simplified by addition of the lanthanide shift reagent (LSR), tris(6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionato)europium(III), 3. The effect of added 3 is twofold. Firstly, the analytical marker signals of the methine proton CHOH in 1 and 2, which are partly overlapped at 60 MHz in CDCl3 (28°), are separated and rendered baseline-resolved due to preferential LSR binding to the less hindered endo OH of 1. Secondly, the absorption signals of the CHOH methines actually sharpen in the presence of 3, and display clearly defined multiplet structure, attributed to full exchange decoupling of the vicinal OH as a result of enhanced OH exchange rates when LSR is present. 相似文献