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1.
E. Rodriguez E. Jimenez G.J. Jacob A.A.R. Neves C.L. Cesar L.C. Barbosa 《Physica E: Low-dimensional Systems and Nanostructures》2005,26(1-4):361
Multilayer PbTe quantum dots (QDs) and SiO2 were grown by pulsed laser deposition (PLD) and Plasma enhanced chemical vapor deposition (PECVD) techniques. The crystalline structure, QD size and size dispersion were observed by high-resolution transmission electron microscopy (HRTEM) measurements. This technique allows one to grow PbTe QDs as small as 1.8 nm diameter and 0.6 nm size dispersion. The whole structure can be used in a Fabry–Perot cavity for an optical device operating at the mid-infrared region. 相似文献
2.
Jacob Schach Møller 《Annales Henri Poincare》2005,6(6):1091-1135
In this paper we analyze the bottom of the energy-momentum spectrum of the translation invariant Nelson model, describing
one electron linearly coupled to a second quantized massive scalar field. Our results are valid for all values of the coupling
constant and include an HVZ theorem, non-degeneracy of ground states, existence of isolated groundstates in dimensions 1 and
2, non-existence of ground states embedded in the bottom of the essential spectrum in dimensions 3 and 4, (i.e., at total
momenta where no isolated groundstate eigenvalue exists), and we study regularity and monotonicity properties of the bottom
of the essential spectrum, as a function of total momentum.
Communicated by Joel Feldman
submitted 04/11/04, accepted 17/02/05 相似文献
3.
Jonathan L. Sessler Patricia J. Melfi Anne E.V. Gorden Doris K. Ford C. Drew Tait 《Tetrahedron》2004,60(49):11089-11097
Hexaphyrin(1.0.1.0.0.0) (isoamethyrin) undergoes a significant color change in the presence of UO22+, PuO22+, and NpO22+. The complexation of the first of these dioxo actinide cations was studied in semi-quantitative fashion in 1:1 MeOH-CH2Cl2. Under these conditions, the detection limit for UO22+ was found to be ca. 5.8 ppm by naked eye monitoring and <28 ppb by UV-vis spectroscopy. Isoamethyrin does not undergo a color change in the presence of most transition metals or when exposed to Gd(III). Isoamethyrin thus constitutes an attractive alternative to 2,2′(1,8-dihydroxy-3,6-disulfonaphthylene-2,7-bisazo)-bisbenzenarsonic acid (AzIII) and 2-(5-bromo-2-pyridylazo)-5-(diethylamino)phenol (BrPADAP), systems currently used as actinide cation sensors. 相似文献
4.
Jacob Fox 《Journal of Combinatorial Theory, Series A》2006,113(1):84-100
We prove that Rado's Boundedness Conjecture from Richard Rado's 1933 famous dissertation Studien zur Kombinatorik is true if it is true for homogeneous equations. We then prove the first nontrivial case of Rado's Boundedness Conjecture: if a1,a2, and a3 are integers, and if for every 24-coloring of the positive integers (or even the nonzero rational numbers) there is a monochromatic solution to the equation a1x1+a2x2+a3x3=0, then for every finite coloring of the positive integers there is a monochromatic solution to a1x1+a2x2+a3x3=0. 相似文献
5.
The periodic precipitation pattern formation in gelatinous media is interpreted as a moving boundary problem. The time law,
spacing law and width law are revisited on the basis of the new scenario. The explicit dependence of the geometric structure
on the initial concentrations of the reactants is derived. Matalon—Packter law, which relates the spacing coefficient with
the initial concentrations is reformulated removing many ambiguities and impractical parameters. Experimental results are
discussed to establish the significance of moving boundary concept in the diffusion controlled pattern forming systems 相似文献
6.
Milind Choubal Warren T. Ford 《Journal of polymer science. Part A, Polymer chemistry》1989,27(6):1873-1882
Crosslinked polystyrene latexes with high surface charge densities have been prepared with 1, 3, and 5 mol% divinylbenzene and 0.5–5.0 mol% of 12-(o-styryloxy)dodecyltrimethylammonium bromide ( 1 ). Within experimental error all of surfactant 1 was incorporated into the particles. Analysis of the latex particles by transmission electron microscopy showed nonspherical shapes, aggregates, and number average diameters ranging from 22 to 95 nm. The particle size decreases and the polydispersity increases with increasing amounts of surfactant 1 and of divinylbenzene in the monomer mixture. A mechanism is proposed for particle formation by precipitation of crosslinked polymer from monomer droplets to form primary particles, coagulation of the primary particles to colloidally stable aggregates, and growth by further polymerization. 相似文献
7.
8.
Two bases of states are presented for modules of the graded parafermionic conformal field theory associated to the coset
. The first one is formulated in terms of the two fundamental (i.e., lowest-dimensional) parafermionic modes. In that basis, one can identify the completely reducible representations, i.e., those whose modules contain an infinite number of singular vectors; the explicit form of these vectors is also given. The second basis is a quasiparticle basis, determined in terms of a modified version of the
exclusion principle. A novel feature of this model is that none of its bases are fully ordered and this reflects a hidden structural
exclusion principle. 相似文献
9.
Mingyang Zhao Warren T. Ford Stefan H. J. Idziak Nicholas C. Maliszewskyj Paul A. Heiney 《Liquid crystals》1994,16(4):583-599
The hexa-4-dodecyloxybenzoyl derivative 1 of azacrown [18]-N6 was originally reported to have a 'tubular' mesophase on the basis of its large central ring and 6-fold symmetry. Starting in the mesophase, annealing of 1 under a cover slip results in formation of a new crystalline phase that melts directly to an isotropic liquid at the temperature previously observed for the mesophase to isotropic transition. Thus the phase behaviour of 1 is kinetically controlled. The analogous hexa-3,4-bisdodecyloxybenzoyl derivative 2 of azacrown [18]-N6 has no kinetic limitations to its phase changes and has an enantiotropic columnar liquid crystalline phase. We have synthesized side chain copolysiloxanes with a (CH2)11 spacer and 75-84 per cent by weight of the same 4-dodecyloxybenzoyl-[18]-N6 mesogen. The polysiloxanes also display a liquid crystalline phase. 相似文献
10.
We consider the semilinear Cauchy problem for a class of pseudo-differential operators generating sub-Markovian semigroups.
Solutions of such problems with negative definite nonlinearity play an important role in constructing branching measure-valued
processes. We establish local existence and uniqueness of solutions in the context of the Dirichlet space associated to the
problem. Comparison and global properties of solutions are also studied.
Accepted 29 August 2001. Online publication 17 December 2001. 相似文献