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591.
Pier Domenico Lamberti 《Applied Mathematics and Optimization》2009,59(3):319-327
We study the dependence of the eigenvalues of a N-dimensional vibrating membrane upon variation of the mass density. We prove that the elementary symmetric functions of the
eigenvalues depend real-analytically on the mass density and that such functions have no critical points with constant mass
constraint. In particular, the elementary symmetric functions of the eigenvalues, hence all simple eigenvalues, have no local
maxima or minima on the set of those mass densities with a prescribed total mass. 相似文献
592.
593.
Pier Luigi Silvestrelli 《Molecular physics》2018,116(21-22):3380-3391
ABSTRACTThe so-called improper blue-shifting (BS) Hydrogen bond, characterising some small complexes, is theoretically investigated by first-principles calculations based on the Density Functional Theory. We compute structural, energetic, electronic and electrostatic properties not only of complexes with linear Hydrogen bonds but also of systems with multiple intermolecular contacts leading to the formation of ‘bifurcated’ or even ‘trifurcated’ Hydrogen bonds. In particular, Hydrogen bonds are characterised in terms of differential electron densities distributions and profiles, and of the shifts of the centres of Maximally localised Wannier Functions. The information from the latter quantities can be conveyed into simple geometric bonding parameters that are helpful in characterising the interatomic bonds. The effect of including dispersion corrections for describing BS Hydrogen bonds is also investigated. Our detailed comparison of the properties of systems with BS Hydrogen bonds to those of others, where more conventional red-shifting Hydrogen bonds are formed, supports the view that there is no fundamental difference between the two kinds of bonds. 相似文献
594.
Pier Luigi Sacchi 《基于设计的结构力学与机械力学》2013,41(2):225-248
ABSTRACT The problem of nonuniform torsion of beams with solid cross-sections is examined in the finite displacement theory of elasticity. Two approximate theories are formulated by applying Reissner's theorem for finite elastic deformations. A perturbation solution scheme is presented, to study results implied by the two approximate formulations. 相似文献
595.
596.
In the present study we show that two-dimensional (2-D) maps together with immuno-detection allow the precise identification of important leukocyte differentiation and tumor markers (e.g., CD3 and CD5), and important cell cycle regulatory molecules such as cyclin dependent kinases, notably CDK6. In addition, the comparative evaluation of molecular expression (e.g., CD5) in maps developed with normal and lymphoma samples can provide reproducible and precise information regarding the molecular expression in different cell populations. Accordingly, we could detect a much increased level of expression of CD5 in mantle cell lymphoma, up to ten times higher than in the control. In addition, CD5 in tumor tissues seems to be microheterogeneous as compared to normal samples. 相似文献
597.
Morphology estimation from normal stress measurements for dilute immiscible polymer blends 总被引:5,自引:0,他引:5
A method to obtain gross blend morphological information from normal stress measurements is proposed. The blend consists of
Newtonian and immiscible constituents in dilute conditions. It is shown that a master curve for the first normal stress difference
(N1) can be readily obtained either theoretically or experimentally. The curve is parametric in the viscosity ratio, and relates
the actual capillary number to the dimensionless interfacial stress. As a consequence, N1 data determine a capillary number
through which a characteristic dimension of the morphology can be estimated. Since globular morphology is typical in dilute
conditions, as an example the master curve is here calculated by using a phenomenological model to describe single drop deformation.
Morphology predictions are compared with experimental data found in the literature; the comparisons give satisfactory results
even up to intermediate concentrations. 相似文献
598.
Luigia Sabbatini Cosimino Malitesta Gemme Morea Luise Torsi Pier G. Zambonin 《Mikrochimica acta》1991,104(1-6):237-243
The potential of a complementary use of X-ray photoelectron spectroscopy and static ToF-SIMS has been exploited with reference to the characterization of electron conducting polymers (polybithiophene) electrochemically synthetized. Particular attention has been focused on the problem of material stability under electrochemical switching.A coherent picture could be drawn showing that irreversible modifications of the surface chemistry occur, strongly dependent on the dryness of the solvent; moreover, the pathway of doping-undoping process can vary noticeably in dependence on the experimental conditions. 相似文献
599.
The use of polystyrene-based anion exchangers with aqueous eluents for the separation of primary aromatic amines has been investigated, and extended with satisfactory results to microcrystalline cellulose, cellulose-based anion-exchangers and sodium CM-cellulose layers.Interesting separations of the amines have also been effected electrophoretically on AG 1-X4 layers.The use of water-organic solvent mixtures on polystyrene-based cation exchangers is discussed. 相似文献
600.
Marengo E Robotti E Cecconi D Hamdan M Scarpa A Righetti PG 《Analytical and bioanalytical chemistry》2004,379(7-8):992-1003
In this paper, principal component analysis (PCA) is applied to a spot quantity dataset comprising 435 spots detected in 18 samples belonging to two different cell lines (Paca44 and T3M4) of control (untreated) and drug-treated pancreatic ductal carcinoma cells. The aim of the study was the identification of the differences occurring between the proteomic patterns of the two investigated cell lines and the evaluation of the effect of the drug Trichostatin A on the protein content of the cells. PCA turned out to be a successful tool for the identification of the classes of samples present in the dataset. Moreover, the loadings analysis allowed the identification of the differentially expressed spots, which characterise each group of samples. The treatment of both the cell lines with Trichostatin A therefore showed an appreciable effect on the proteomic pattern of the treated samples. Identification of some of the most relevant spots was also performed by mass spectrometry. 相似文献