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Callegari G Tyomkin I Kornev KG Neimark AV Hsieh YL 《Journal of colloid and interface science》2011,353(1):290-293
Characterization of transport and absorption properties of nanofiber webs is a challenge, because in many cases the material is soft and cannot withstand the stresses exerted by the standard instruments. In this paper, we report on development of a new technique for materials characterization. We propose to conduct wicking and permeability experiments for full characterization of the nanowebs. As an example, we used electrospun cellulose acetate nanowebs. The wicking experiments showed very good reproducibility, demonstrating the square-root-of-time dependence of wetting front position vs time. The prefactor depends on a product of capillary pressure and materials permeability. We developed a technique to independently measure the permeability of small samples of nanowebs. Wicking and permeability data allow one to estimate the pore size; SEM micrographs confirmed the obtained estimates of pore radius. In general, the proposed method allows one to characterize the transport and absorption parameters of the nanofibrous materials for which the standard procedures are inapplicable. 相似文献
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Throughout this paper we study the existence of irreducible curves on smooth projective surfaces with singular points of prescribed topological types . There are necessary conditions for the existence of the type for some fixed divisor on and suitable coefficients , and , and the main sufficient condition that we find is of the same type, saying it is asymptotically proper. Ten years ago general results of this quality were not known even for the case . An important ingredient for the proof is a vanishing theorem for invertible sheaves on the blown up of the form , deduced from the Kawamata-Vieweg Vanishing Theorem. Its proof covers the first part of the paper, while the middle part is devoted to the existence theorems. In the last part we investigate our conditions on ruled surfaces, products of elliptic curves, surfaces in , and K3-surfaces.
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In this paper we present a general patchworking procedure for the construction of reduced singular curves having prescribed
singularities and belonging to a given linear system on algebraic surfaces. It originates in the Viro “gluing” method for
the construction of real non-singular algebraic hypersurfaces. The general procedure includes almost all known particular
modifications, and goes far beyond. Some applications and examples illustrate the construction.
Both authors were partially supported by the Herman Minkowsky-Minerva Center for Geometry at Tel Aviv University, and by grant
no. G-616-15.6/99 from the German-Israeli Foundation for Research and Development. The first author was also supported by
the Bessel Research Award from the Alexander von Humboldt Foundation. The second author was also partially supported by the
EC-network ‘Algebraic Lie Representations” contract no. ERB-FMRX-CT97-0100. 相似文献
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We study certain algebraic properties of the small quantum homology algebra for the class of symplectic toric Fano manifolds.
In particular, we examine the semisimplicity of this algebra, and the more general property of containing a field as a direct
summand. Our main result provides an easily verifiable sufficient condition for these properties which is independent of the
symplectic form. Moreover, we answer two questions of Entov and Polterovich negatively by providing examples of toric Fano
manifolds with non-semisimple quantum homology, and others in which the Calabi quasi-morphism is not unique.
相似文献
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In this paper, we show that Severi varieties parameterizing irreducible reduced planar curves of a given degree and geometric genus are either empty or irreducible in any characteristic. Following Severi’s original idea, this gives a new proof of the irreducibility of the moduli space of smooth projective curves of a given genus in positive characteristic. It is the first proof that involves no reduction to the characteristic zero case. As a further consequence, we generalize Zariski’s theorem to positive characteristic and show that a general reduced planar curve of a given geometric genus is nodal.
相似文献8.
In this paper we present various particular versions of the general patch-working procedurefor the construction of reduced
algebraic curves with prescribed singularities, on algebraic surfaces. Among the main examples are a deformation of reducible
algebraic curves on reducible algebraic surfaces in the presence of non-transverse intersections of a curve with the singular
locus of a surface, and a deformation of curves with multiple components. As an application we deduce, a significant asymptotical
improvement for the sufficient existence criterion of algebraic curves with arbitrary prescribed singlarities in given linear
systems on smooth projective algebraic surfaces.
Both authors were partially supported by the Herman Minkowsky-Minerva Center for Geometry at Tel Aviv University, and by grant
no. G-616-15.6/99 from the German-Israeli Foundation for Research and Development. The first author was also supported by
the Bessel Research Award from the Alexander von Humboldt Foundation. 相似文献
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