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51.
52.
Rupture of intracranial saccular aneurysms is the leading cause of spontaneous subarachnoid hemorrhage, which results in significant
morbidity and mortality. Although many have suggested that saccular aneurysms enlarge and rupture due to mechanical instabilities,
our recent nonlinear analyses suggest that at least certain classes of aneurysms do not exhibit a quasi-static limit point
instability or dynamic instabilities in response to periodic loading. Based on an increased understanding of the ubiquitous
role of growth and remodeling within the vasculature and recent histopathological data on saccular aneurysms, it is hypothesized
that a stress-mediated regulation of collagen turnover causes their enlargement. There is a need, however, for a theoretical
framework to explore this and competing hypotheses. In this paper, we present a 2-D constrained mixture model for growth and
remodeling of an ellipsoidally shaped saccular aneurysm and numerically simulate enlargement and changes in material symmetry
in the aneurysmal wall. Results suggest that ellipsoidal aneurysms tend toward spherical shapes, and a competition between
radial expansion and wall thickening plays a critical role in determining the stability of an enlarging lesion. 相似文献
53.
Thivisha Rajagopal 《Tetrahedron》2010,66(45):8739-8744
E-β-Chloro-α-iodo-α,β-unsaturated esters were converted to single isomer trisubstituted olefins bearing alkyl substituents by using and alkyl-Suzuki cross coupling. The process was highly selective, and the products in all cases were isolated as single isomers. Mechanistic investigations indicated that this process transfers a hydrogen from water to the α-position of the substrate, and then an alkyl group is introduced to the β-position of the intermediate template while replacing a chloride. 相似文献
54.
55.
K. Swarnalatha E. Rajkumar S. Rajagopal R. Ramaraj I. Sadhiya Banu P. Ramamurthy 《Journal of Physical Organic Chemistry》2011,24(1):14-21
The reaction of phenols with the excited state, *[Ru(bpy)3]2+ (E0 = 0.76 V) and *[Ru(H2dcbpy)3]2+, (dcbpy = 4,4′‐dicarboxy‐2,2′‐bipyridine) (E0 = 1.55 V vs. SCE) complexes in CH3CN has been studied by luminescence quenching technique and the quenching is dynamic. The formation of phenoxyl radical as a transient is confirmed by its characteristic absorption at 400 nm. The kq value is highly sensitive to the change of pH of the medium and ΔG0 of the reaction. Based on the treatment of kq data in terms of energetics of the reaction and pH of the medium, proton coupled electron transfer (PCET) mechanism has been proposed for the reaction. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
56.
We consider the flow of a class of incompressible fluids which are constitutively defined by the symmetric part of the velocity gradient being a function, which can be non-monotone, of the deviator of the stress tensor. These models are generalizations of the stress power-law models introduced and studied by J. Málek, V. Pr??a, K.R. Rajagopal: Generalizations of the Navier-Stokes fluid from a new perspective. Int. J. Eng. Sci. 48 (2010), 1907–1924. We discuss a potential application of the new models and then consider some simple boundary-value problems, namely steady planar Couette and Poiseuille flows with no-slip and slip boundary conditions. We show that these problems can have more than one solution and that the multiplicity of the solutions depends on the values of the model parameters as well as the choice of boundary conditions. 相似文献
57.
Qiang Lai Xiao-Wen Zhao Jian-Ning Huang Viet-Thanh Pham Karthikeyan Rajagopal 《The European physical journal. Special topics》2018,227(7-9):719-730
This letter gives a general review on the monostability, bistability, periodicity and chaos in gene regulatory network. Some simple motifs that generate monostability, bistability, periodicity and chaos are analytically and numerically reported. Further research directions of the nonlinear dynamics of gene regulatory network are discussed. 相似文献
58.
Gurusamy Rajagopal Shanmugam Selvaraj Karuthamohamed Dhahagani 《Tetrahedron: Asymmetry》2010,21(18):2265-2270
Various ketones have undergone asymmetric trimethylsilylcyanation at room temperature with (CH3)3SiCN (TMSCN) in the presence of a chiral-supported Cu(salen) complex and Ph3PO as the catalyst. Aromatic, aliphatic, and heterocyclic ketones have been converted into the corresponding cyanohydrin trimethylsilyl ethers in 83?96% yields with 52?84% ee. Several factors concerning the reactivity and enantioselectivity have been discussed. A double activation where Cu(salen) plays the role of Lewis acid and Ph3PO acts as a Lewis base is reported. Poly(ethylene glycol) monomethyl ether (MeO-PEG) has been used as a soluble support while JandaJel (JJ) and Merrifield (MF) resins served as insoluble supports. Each polymer is linked to the salen catalyst through a glutarate spacer. The soluble catalysts were recovered by precipitation with a suitable solvent while the insoluble catalysts were simply filtered from the reaction mixture. The JandaJel-attached Cu(salen) catalyst could be used for five cycles with the retention of efficiency and the Merrifield-bound Cu(salen) catalyst was found to loose activity with each use. 相似文献
59.
A theoretical framework for treating the effects of magnetic fieldH on the pairing theory of superconductivity is considered, where the field is taken in an arbitrary direction with respect
to crystal axes. This is applicable to closed, as well as open normal state Fermi surface (FS), including simple layered metals.
The orbital effects of the magnetic field are treated semiclassically while retaining the full anisotropic paramagnetic contribution.
Explicit calculations are presented in the limits |H| → |H
c2(T)|,T ∼ 0 andT →T
c(|H|), |H| ∼ 0. Effects of weak nonmagnetic impurity scattering, without vertex corrections, have also been taken into account in a
phenomenological way. The final results for the case of open FS and layered materials are found to differ considerably from
those of the closed FS. For example, an important parameter,h(T=0)=|Hc2(0)|/[-Tδ|H
c2
T|δT]T{s0} for the case of a FS open ink
z-direction with thek
z-bandwidth, 4t
3, very small compared to the Fermi energy,E
F, is close to 0.5906, compared to 0.7273 for the closed FS, in the clean limit. Analytical results are given for the magnetic
field dependence ofT
c and the temperature dependence of H
c2 for a model of layered superconductors with widely open FS. For a set of band structure parameters for YBa2Cu3O7 used elsewhere, we find reasonable values for the upper critical fieldH
c2(0), the slope (dH
c2/dT)T
c0, anisotropic coherence lengths ζi(T=0),i=x, y, z, and (dT
c/d|H|)|H| → 0. 相似文献
60.