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61.
Fading memory is a distinguishing characteristic of viscoelastic solids. Its assessment is often achieved by measuring the stress due to harmonic strain histories at different frequencies: from the experimental point of view, the storage and loss moduli are, hence, introduced. On the other side, the mathematical modeling of viscoelastic materials is usually based on the consideration of a kernel function whose decay rate is sufficiently fast. For several different solid materials, we have collated experimental evidence showing an high sensitivity to frequency variations of both the storage and loss moduli. By contrast, we prove that the commonly employed viscoelastic kernels (Prony series, continuous kernel, etc.) cannot reproduce this experimental behavior, as the resulting frequency sensitivity of the storage modulus is always zero when assessed at low frequency. This leads to identification problems of the material parameters which are strongly ill conditioned. However, we identify the specific kernel property which is responsible for this misbehavior: the long-term material memory must not decrease too fast. Some viscoelastic kernels, showing the correct memory??s rate of decay, are introduced and their improved ability to match the experimental data analyzed. 相似文献
62.
We study structural properties of the q-color Potts field theory which, for real values of q, describes the scaling limit of the random cluster model. We show that the number of independent n-point Potts spin correlators coincides with that of independent n-point cluster connectivities and is given by generalized Bell numbers. Only a subset of these spin correlators enters the determination of the Potts magnetic properties for q integer. The structure of the operator product expansion of the spin fields for generic q is also identified. For the two-dimensional case, we analyze the duality relation between spin and kink field correlators, both for the bulk and boundary cases, obtaining in particular a sum rule for the kink-kink elastic scattering amplitudes. 相似文献
63.
Light transport in superdiffusive media of finite size is studied theoretically. The intensity Green's function for a slab geometry is found by discretizing the fractional diffusion equation and employing the eigenfunction expansion method. Truncated step length distributions and complex boundary conditions are considered. The profile of a coherent backscattering cone is calculated in the superdiffusion approximation. 相似文献
64.
Beatrice Rubin Jacopo Manso Halenya Monticelli Loris Bertazza Marco Redaelli Francesca Sensi 《Natural product research》2019,33(11):1646-1649
Oregano (Origanum vulgare L.) is a common aromatic plant used in Mediterranean and Asian Regions for treating respiratory diseases, painful menstruation, rheumatoid arthritis, etc. Recently its role as an anticancer plant has been suggested, although oregano has been never evaluated into adrenocortical tumour cell models. This study analysed for the first time the anticancer effects of a crude extract of wild mountain oregano (Origanum vulgare L.) in SW13 and H295R cell lines. The crude extract was characterised by GC/MS and the toxic effects of oregano were first analysed by brine shrimp lethality assay. Our findings demonstrated that oregano decreased cell viability, survival, modified cell cycle and induced cell death (through necrotic process) and that the effects can be attributed to a blockade of MAPK and PI3 K/Akt pathways. These results suggest that oregano extract exerts anticancer activities in adrenocortical tumour cell lines, providing evidence for further research in higher models. 相似文献
65.
Diamond James Profili Jacopo Hamdan Ahmad 《Plasma Chemistry and Plasma Processing》2019,39(6):1483-1498
Plasma Chemistry and Plasma Processing - Plasma in- or in-contact-with liquid is an emerging technology that has high potential for use in liquid treatment applications. Due to the simultaneous... 相似文献
66.
An improved iterative solution to solve the electrostatic problem in the polarizable continuum model
Christian Silvio Pomelli Jacopo Tomasi Vincenzo Barone 《Theoretical chemistry accounts》2001,105(6):446-451
We present a discrete iterative interpolation scheme (DIIS) to improve the convergence rate of electrostatic calculations
in the polarizable continuum model (PCM) to describe solvent effects on molecular solutes. The electrostatic calculations
may easily become the bottleneck of the calculation when the solute size is large. For large molecules iterative procedures
turn out to be computationally more convenient than matrix inversion or closure methods. The DIIS scheme is compared here
to another iterative procedure (DAMP) and to the biconjugate gradient (BCG) method. The comparisons show that DIIS leads to
a sizeable saving of computational time for the C-PCM and IEF-PCM methods (average 40%) compared to DAMP, and more than 50%
with respect to the BCG method.
Received: 5 October 2000 / Accepted: 13 November 2000 / Published online: 19 January 2001 相似文献
67.
We review in these notes the theory of equivariant embeddings of spherical homogeneous spaces. Given a spherical homogeneous space G/H, the normal equivariant embeddings of G/H are classified by combinatorial objects called colored fans, which generalize the fans appearing in the classification of toric varieties and which encode several geometric properties of the corresponding variety. 相似文献
68.
A new implementation of analytical gradients for the polarizable continuum model is presented, which allows Hartree-Fock and density functional calculations taking into account both electrostatic and nonelectrostatic contributions to energies and gradients for closed and open shell systems. Simplified procedures neglecting the derivatives of the cavity surface and/or using single spheres for XHn groups have also been implemented and tested. The solvent-induced geometry relaxation has been studied for a number of representative systems in order to test the efficiency of the procedure and to investigate the role of different contributions. © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 404–417, 1998 相似文献
69.
70.
Acta Mechanica Sinica - Nature and technology often adopt structures that can be described as tubular helical assemblies. However, the role and mechanisms of these structures remain elusive. In... 相似文献