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101.
A system is in a self-organized critical state if the distribution of some measured events obeys a power law. The finite-size scaling of this distribution with the lattice size is usually enough to assume that the system displays self-organized criticality. This approach, however, can be misleading. In this paper we analyze the behavior of the branching rate sigma of the events to establish whether a system is in a critical state. We apply this method to the Olami-Feder-Christensen model to obtain evidence that, in contrast to previous results, the model is critical in the conservative regime only. 相似文献
102.
Gotor Rafael Prado López Pilar Pérez Pilar Jiménez Rafael Sánchez Francisco Burgess John 《Transition Metal Chemistry》2002,27(2):127-133
Dependences of rate constants on added salt concentrations have been established for approach to equilibrium for reaction of pyrazinecarboxylato-bis-1,2-diaminoethane-cobalt(III) with the pentacyanoferrate(II) complex [Fe(CN)5L]3– with L = MeCN. Added salt effects on dissociation of the binuclear bis-1,2-diaminoethanecobalt(III)(-pyrazine-carboxylato)pentacyanoferrate(II), [(en)2Co(-pzCO2)Fe(CN)5]–, produced in this reaction are compared with those on dissociation of other pentacyanoferrate(II) complexes. The activation volume for dissociation of this binuclear complex has been derived from the observed salt effects via the dependence of rate constants on surface tension and the thence-derived surface area of activation. 相似文献
103.
Highly conductive boron-doped diamond (BDD) electrodes are well suited for performing electrochemical measurements of nucleic acids in aqueous solution under diffusion-only control. The advantageous properties of this electrodic material in this context include reproducibility and the small background currents observed at very positive potentials, along with its robustness under extreme conditions so offering promising capabilities in future applications involving thermal heating or ultrasonic treatment. tRNA, single and double stranded DNA and 2'-deoxyguanosine 5'-monophosphate (dGMP) have been studied and well defined peaks were observed in all cases, directly assignable to the electro-oxidation of deoxyguanosine monophosphate. 相似文献
104.
Silva Frederico M. A. Soares Renata M. del Prado Zenón G. N. Gonçalves Paulo Batista 《Nonlinear dynamics》2020,102(2):877-906
Nonlinear Dynamics - This work presents the mathematical modeling for the nonlinear vibration analysis of membrane and shell structures of arbitrary shape. These structures are usually the optimal... 相似文献
105.
Abstract This paper is devoted to investigate extinction and nonextinction conditions of the extended Beverton–Holt equation (BHE) for dynamics of populations in Ecology when potential discontinuities at sampling points are included in the model. The proposed model is described by means of four sequences of parameters. Two of them are the intrinsic growth rate and the carrying capacity sequences which are included in the basic BHE model. The other two ones, namely, the harvesting (i.e., the hunting or fishing quota) and the internal consumption (which can include positive and negative migrations in the considered population habitat) sequences are included to parameterize the model discontinuities. Such discontinuities are related to impulses in the corresponding continuous‐time logistic equation. The obtained results establish how the harvesting quota and/or the internal consumption has to be fixed to guarantee the population nonextinction or, eventually, its extinction. Finally, some controllability results related to the search of a carrying capacity sequence such that the solution of the proposed impulsive BHE tracks a reference one are obtained. 相似文献
106.
Alessandra Gomes Cioletti Ricardo José Alves José Dias de Souza Filho Josiano Gomes Chaves Maria Auxiliadora Fontes Prado 《合成通讯》2013,43(11):2019-2028
A simple and inexpensive methodology for the selective hydrolysis of acetals using hydrogen chloride as catalyst is described. 相似文献
107.
Dr. Yoann Prado Dr. Marie‐Anne Arrio Dr. Florence Volatron Dr. Edwige Otero Dr. Christophe Cartier dit Moulin Dr. Philippe Sainctavit Dr. Laure Catala Prof. Dr. Talal Mallah 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(21):6685-6694
The local symmetry and local magnetic properties of 6 nm‐sized, bimetallic, cyanide‐bridged CsNiCr(CN)6 coordination nanoparticles 1 and 8 nm‐sized, trimetallic, CsNiCr(CN)6@CsCoCr(CN)6 core–shell nanoparticles 2 were studied by X‐ray absorption spectroscopy (XAS) and X‐ray magnetic circular dichroism (XMCD). The measurements were performed at the NiII, CoII, and CrIII L2,3 edges. This study revealed the presence of distorted NiII sites located on the particle surface of 1 that account for the uniaxial magnetic anisotropy observed by SQUID measurements. For the core–shell particles, a combination of the exchange anisotropy between the core and the shell and the pronounced anisotropy of the CoII ions is the origin of the large increase in coercive field from 120 to 890 Oe on going from 1 to 2 . In addition, XMCD allows the relative orientation of the magnetic moments throughout the core–shell particles to be determined. While for the bimetallic particles of 1 , alignment of the magnetic moments of CrIII ions with those of NiII ions leads to uniform magnetization, in the core–shell particles 2 the magnetic moments of the isotropic CrIII follow those of CoII ions in the shell and those of NiII ions in the core, and this leads to nonuniform magnetization in the whole nanoobject, mainly due to the large difference in local anisotropy between the CoII ions belonging to the surface and the NiII ions in the core. 相似文献
108.
A granular jet falling out of a funnel shaped container, subjected to small vertical vibrations, develops an instability farther downstream as may happen for ordinary liquid jets. Our results show that this instability is reminiscent of the Rayleigh-Plateau capillary instability leading to breakup of the jet at large scales. The first stages of this instability are captured in detail allowing a determination of the dispersion relation. Surface tensions measured in this unstable regime (of the order of mN/m) are in agreement with previously reported measurements carried out at much smaller scales. This instability and the breakup of the jet can be inhibited when the effect of the surrounding medium (air) is reduced by enclosing the jet in an evacuated chamber, showing that the effective surface tension measured is the result of a strong interaction with the surrounding air. 相似文献
109.
Cândida Maria Soares de Mendonça Igor Prado de Barros Lima Cícero Flávio Soares Aragão Ana Paula Barreto Gomes 《Journal of Thermal Analysis and Calorimetry》2014,115(3):2277-2285
Thermogravimetry (TG) and differential scanning calorimetry (DSC) are used in pharmaceutical studies for characterization of drugs, purity, compatibility of formulations, identification of polymorphism, evaluation of stability, and thermal decomposition of drugs and pharmaceutical formulations. Hydroquinone (HQ) and products containing HQ have been widely used as depigmentation agents for lightening the skin. Retinoids are compounds that have the basic core structure of vitamin A and its oxidized metabolites, or synthetic compounds that share similar mechanisms of action as naturally occurring retinoids. Depigmentants and excipients were analyzed by TG and DSC. The dynamic thermogravimetric curves were obtained on a SHIMADZU thermobalance, model DTG-60, using an alumina crucible, at the heating rate of 10 °C min?1, in the temperature range of 25–900 °C, under an atmosphere of nitrogen at 50 mL min?1. The sample's mass was 10 ± 0.05 mg. The DSC curves were obtained using Shimadzu calorimeter, model DSC-60, using aluminum crucible, at the heating rate of 10 °C min?1, in the temperature range of 25–400 °C. The thermogravimetric and calorimetric curves were analyzed using TASYS software SHIMADZU. In this study were found the interaction between retinoic acid (RA) and the following excipients: cetyl alcohol(CA), cetostearyl alcohol (CTA), glycerin(GLY), and dipropylene glycol (DPG), and that between HQ and the excipient, DPG. Therefore, additional studies are necessary to evaluate final formulations. Thermal analysis is an effective and reliable technique that can be used in the control of raw materials and pharmaceutical products, and for evaluating their employment potential in the development and characterization of products. 相似文献
110.
We study the nonlinear evolutionary euclidean bosonic string equation on the Euclidean space \({\mathbb {R}}^n\). We interpret the nonlocal operator \(\Delta e^{-c\,\Delta }\) using entire vectors of \(\Delta \) in \(L^2({\mathbb {R}}^n)\). We prove that it generates a bounded holomorphic \(C_0\)-semigroup on \(L^2({\mathbb {R}}^n)\) (so that it also satisfies maximal \(L^p\) regularity) and we show the well-posedness of the corresponding nonlinear Cauchy problem.
相似文献
$$\begin{aligned} u_t = \Delta e^{-c \Delta }\,u + U(t,u) , \quad c > 0 \; \end{aligned}$$