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191.
Y. S. Hong K. C. Kim V. I. Volkov V. D. Skirda C. -H. Lee 《Applied magnetic resonance》2005,29(2):351-361
The diffusion phenomenon of a nonionic surfactant, polyoxyethylene sorbitan monooleate (POE-SMO), micelle in aqueous solution
was investigated by pulsed field gradient nuclear magnetic resonance (PFG NMR) with a high gradient strength of 17.4 T/m at
the diffusion timet
d varied from 3 to 300 ms. This high gradient strength allowed us to measure the slow self-diffusion coefficient of POE-SMO
micelle, and the short diffusion time below 10 ms showed the restricted diffusion of the micelle. At the shortt
d the self-diffusion of the micelle was restricted and the restricted sizes were 1.8, 1.5, and 0.8 μm for the POE-SMO concentration
of 100, 200 and 300 mM, respectively, and 0.6 μm for the POE-SMO only. The possible reason of this restriction was assumed
to be the formation of a spatial network or a micellar clustering. Furthermore, a proton exchange between water molecule and
surfactant OH group on the micelle surface was proposed. With respect to this proposal, the residence time of the proton at
the micelle surface and the thickness of the surface were investigated from proton self-diffusion coefficients by PFG NMR. 相似文献
192.
It is wellknown that the technique of character sums together with the tools of algebraic number theory is the adequate method for the study of difference sets in abelian groups, compare for instance Ott [5] or Turyn [6]. In this paper we use this method to prove a new non-existence theorem for certain difference sets in abelian groups of order rpa rp^a , where r 1 2 r \neq 2 and p are distinct primes. 相似文献
193.
Andrei N. Yakunin 《Central European Journal of Physics》2004,2(3):535-555
A cubic structure of polymer colloid complexes is studied. The technique of the research includes i) an analysis of well-known
literature SAXS data; on this basis, ii) constructing a simple model to estimate geometric structure parameters and to obtain
a simulated scattering curve; and iii) comparing the model with the real structure obtained from the SAXS data, using the
reconstruction of electron density distribution. A bicontinuous structure in cubic mesophases is formed.
Dedicated to the memory of Alexander T. Dembo 相似文献
194.
We consider a discretized volume V consisting of finite, congruent and attached copies of a tile t. We find a group L
V
the orbit of which, when applied to t, is just V. We show the connection between the structural matrixQ in the formal solution of a boundary value problem formulated for volume V and the so called auxiliary matrix of the graph Γ
v
associated with V. We show boundary value problems to be isomorphic if the graphs associated with the volumes are isomorphic, or, if the covering
groups are Sunada pairs. 相似文献
195.
196.
Su-Yun Huang Chuhsing Kate Hsiao Ching-Wei Chang 《Annals of the Institute of Statistical Mathematics》2003,55(3):655-670
The article provides a refinement for the volume-corrected Laplace-Metropolis estimator of the marginal likelihood of DiCiccioet al. The correction volume of probability α in DiCiccioet al. is fixed and suggested to take the value α=0.05. In this article α is selected based on an asymptotic analysis to minimize
the mean square relative error (MSRE). This optimal choice of α is shown to be invariant under linear transformations. The
invariance property leads to easy implementation for multivariate problems. An implementation procedure is provided for practical
use. A simulation study and a real data example are presented. 相似文献
197.
Christian Hainzl Vitali Vougalter Semjon A. Vugalter 《Communications in Mathematical Physics》2003,233(1):13-26
We consider a spinless particle coupled to a photon field and prove that even if the Schr?dinger operator p
2
+V does not have eigenvalues the system can have a ground state. We describe the coupling by means of the Pauli-Fierz Hamiltonian
and our result holds in the case where the coupling constant α is small.
Received: 7 January 2002 / Accepted: 8 November 2002 Published online: 13 January 2003 相似文献
198.
We study the focusing problem for the eikonal equation¶¶ ?tu=| ?u| 2, \partial _{t}u=\left| \nabla u\right| ^{2}, ¶¶i.e., the initial value problem in which the support of the initial datum is outside some compact set in Rd \mathbf{R}^{d} . The hole in the support will be filled in finite time and we are interested in the asymptotics of the hole as it closes. We show that in the radially symmetric case there are self-similar asymptotics, while in the absence of radial symmetry essentially any convex final shape is possible. However in R2 \mathbf{R}^2 , for generic initial data the asymptotic shape will be either a vanishing triangle or the region between two parabolas moving in opposite directions (a closing eye). We compare these results with the known results for the porous medium pressure equation which approaches the eikonal equation in the limit as m? 1 m\rightarrow 1 . 相似文献
199.
Herbert Henning 《ZDM》2003,35(4):172-176
The author discusses at some examples exemplarily, how the pedagogy of mathematics education in the GDR from curricular and educational/psychological knowledge from the time before 1945 has developed scientifically. 相似文献
200.