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241.
Angeles Carmona Andres M. Encinas Margarida Mitjana 《International journal of quantum chemistry》2014,114(24):1670-1677
Here, we consider a class of generalized linear chains; that is, the ladder‐like chains as a perturbation of a 2n path by adding consecutive weighted edges between opposite vertices. This class of chains in particular includes a big family of networks that goes from the cycle, unicycle chains up to ladder networks. In this article, we obtain the Green function, the effective resistance, and the Kirchhoff index of ladder‐like chains in terms of the Green function, the effective resistance, and the Kirchhoff index of the path. © 2014 Wiley Periodicals, Inc. 相似文献
242.
Maria Elisa Rodrigues Ana Rita Costa Mariana Henriques Philip Cunnah David W. Melton Joana Azeredo Rosário Oliveira 《Applied biochemistry and biotechnology》2013,169(4):1279-1291
Currently, mammalian cell technology has become the focus of biopharmaceutical production, with strict regulatory scrutiny of the techniques employed. Major concerns about the presence of animal-derived components in the culture media led to the development of serum-free (SF) culture processes. However, cell adaptation to SF conditions is still a major challenge and limiting step of process development. Thus, this study aims to assess the impact of SF adaptation on monoclonal antibody (mAb) production, identify the most critical steps of cell adaptation to the SF EX-CELL medium, and create basic process guidelines. The success of SF adaptation was dependent on critical steps that included accentuated cell sensitivity to common culture procedures (centrifugation, trypsinization), initial cell concentration, time given at each step of serum reduction, and, most importantly, medium supplements used to support adaptation. Indeed, only one of the five supplement combinations assessed (rhinsulin, ammonium metavanadate, nickel chloride, and stannous chloride) succeeded for the Chinese hamster ovary-K1 cell line used. This work also revealed that the chemically defined EX-CELL medium benefits mAb production in comparison with the general purpose Dulbecco’s Modified Eagle’s Medium, but the complete removal of serum attenuates these positive effects. 相似文献
243.
Margarida Brito Ana Cristina Moreira Freitas 《Statistics & probability letters》2010,80(23-24):1835-1843
We consider the estimation of the tail-index for dependent random variables. We establish the consistency of the geometric-type estimator (Brito and Freitas, 2003) for stationary sequences satisfying general mixing conditions and derive a simplified condition, specially adapted for applications. 相似文献
244.
To shed light on the microscopic mechanism of hydrophobic hydration, we study a simplified lattice model for water solutions in which the orientational nature of hydrogen bonding as well as the degeneracy related to proton distribution are taken into account. Miscibility properties of the model are looked at for both polar (hydrogen bonding) and nonpolar (non-hydrogen bonding) solutes. A quasichemical solution for the pure system is reviewed and extended to include the different kinds of solute. A Monte Carlo study of our model yields a novel feature for the local structure of the hydration layer: energy correlation relaxation times for solvation water are larger than the corresponding relaxation times for bulk water. This result suggests the presence of ordering of water particles in the first hydration shell. A nonassociating model solvent, represented by a lattice gas, presents opposite behavior, indicating that this effect is a result of the directionality of the interaction. In presence of polar solutes, we find an ordered mixed pseudophase at low temperatures, indicating the possibility of closed loops of immiscibility. 相似文献
245.
M. C. Freitas A. M. G. Pacheco H. M. Anawar I. Dionísio H. M. Dung N. Canha A. Bettencourt F. Henriques C. J. Pinto-Gomes S. Capelo 《Journal of Radioanalytical and Nuclear Chemistry》2009,282(1):21-27
This study has determined contamination levels in soils and plants from the São Domingos mining area, Portugal, by k 0-INAA. Total concentrations of As, Sb, Cr, Hg, Cu, Zn and Fe in soils were very high, exceeding the maximum limits in Portuguese legislation. Concentrations of toxic elements like As, Sb and Zn were highest in roots of Erica andevalensis, Juncus acutus, Agrostis castellana and Nicotiana glauca. Additionally, As, Br, Cr, Fe, Sb and Zn in all organs of most plants were above toxicity levels. Those species that accumulated relatively high concentrations of toxic elements in roots (and tops) may be cultivated for phytostabilisation of similar areas. 相似文献
246.
Let S be a Campedelli surface (a minimal surface of general type with p
g
= 0, K
2 = 2), and an etale cover of degree 8. We prove that the canonical model of Y is a complete intersection of four quadrics . As a consequence, Y is the universal cover of S, the covering group G = Gal(Y/S) is the topological fundamental group π
1
S and G cannot be the dihedral group D
4 of order 8.
The first author is a member of the Centre for Mathematical Analysis, Geometry and Dynamical Systems, Instituto Superior Técnico,
Lisboa. The second is a member of G.N.S.A.G.A.–I.N.d.A.M. 相似文献
247.
We investigate the generation of gravitational waves in power-law inflationary models. The energy spectrum of the gravitational
waves is calculated using the method of continuous Bogoliubov coefficients. We show that, by looking at the interval of frequencies
between 10−5 and 105 Hz and also at the GHz range, important information can be obtained, both about the inflationary period itself and about
the thermalization regime between the end of inflation and the beginning of the radiation-dominated era. We thus deem the
development of gravitational wave detectors, covering the MHz/GHz range of frequencies, to be an important task for the future. 相似文献
248.
A.F.S. Moreira W. Figueiredo V.B. Henriques 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,27(1):153-159
We performed a detailed Landau expansion of the free energy for a metamagnetic model considering terms up to twelfth order.
We obtained explicit expressions for the coefficients as a function of the temperature and the ratio between ferro- and antiferromagnetic
interactions. We showed that a naive analysis based on the signs of these coefficients cannot always give us sufficient guarantee
about the correctness of the phase diagram of the model. In these cases it is necessary to resort to the full expression of
the free energy in order to characterize the nature of the phase transition.
Received 28 November 2001 相似文献
249.
A. B. Henriques 《Zeitschrift fur Physik C Particles and Fields》1983,18(3):213-218
A non-relativistic potential model is applied to the study of light-meson spectroscopy. The general agreement between the predictions of the model and the data is good, but some resonances, among them the ε(1.300), ?(1.640) andS *(0.980), are not easily explained. Another potential source of problems concerns the situation of the 1D-wave states. 相似文献
250.